Fish Oil, Krill Oil, and Algal Oil Omega-3 (DHA & EPA) Supplements Review

Find the Best Fish Oil & Compare to Prescription Omega-3 Drugs. See Our Top Picks Among Fish Oil & Other Omega-3 Supplements for Adults, Children and Pets.

Medically reviewed and edited by Tod Cooperman, M.D.

Last Updated: 11/18/2021 | Initially Posted: 11/29/2020Latest Update: Fish Oil for COVID?

Table of Contents

Summary

· What are the benefits of fish oil? Taking a supplement with EPA and DHA from fish oil (or other source, such as krill oil or algae) offers a wide range of potential benefits for mental health, treating inflammatory disease, maintaining muscle, and even cancer prevention (see What It Does). As far as cardiovascular and cognitive (and memory) benefits, eating fish at least twice each week may do you more good than taking a fish oil supplement, although, if you eat fish, be aware that some types can be high in mercury -- see Getting EPA and DHA from Food).

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How much fish oil should you take? Different amounts of EPA and DHA have been used for different purposes. A general daily dose is about 300 to 500 mg of EPA and DHA, while some treatments (such as for high triglycerides) involve doses as high as 4,000 mg per day (see What to Consider When Using - Dosage). Focus on the amounts of EPA and DHA in a product rather than the amount of total oil, since the concentration of EPA and DHA in oils ranges from about 33% to 85% and, for some uses, you may want more EPA or more DHA (see the comparison graph and second column of the Results table below for amounts of EPA and DHA and concentration levels, as well as amounts of "the other omega-3" DPA, and omega-7 fatty acids).

· When is the best time to take fish oil? Taking fish oil with a meal containing other fats may improve absorption. If you need a high daily dose, dividing the dose over the course of the day may reduce any unpleasant aftertaste and "fishy burps." Enteric-coated capsules can also reduce these effects but may possibly reduce absorption.

· What is the best form of fish oil? Fish oil in supplements is generally first processed to purify it. This often involves modifying its chemical form. While all forms can help raise EPA and DHA levels and do so equally well if taken with a high-fat meal, if not taken with a high-fat meal the "re-esterified triglyceride" (or just "triglyceride") form may be the best absorbed, with up to 76% greater absorption than from the more common "ethyl ester" form (see ConsumerTips™ -- Forms of Fish Oil). You can check the form of each product in the second column of the table below.

· Which fish, krill, and algal oils are the best? Choose a supplement listed as Approved by ConsumerLab.com in the table below, because not all supplements contain their listed amounts of omega-3 fatty acids, and some may be rancid or contaminated. If you need a high dose, it may be more convenient to pick one with a higher concentration (see the 4th column of the table) so that you can take fewer and/or smaller pills or other units. Compare prices to save money (see comparison graph and 5th column of the Results table). To save time, see our Top Picks — these are Approved products that offer exceptional value compared to other products in their categories, including fish oils in softgels, enteric-coated capsules, bottled liquids, as a prenatal supplement, for children, and for pets, as well as our Top Picks for krill oil and vegetarian algal oil (from algae). We also have Top Picks for getting DPA (the "other omega-3") and omega-7 fatty acids. You'll see that you can get high-quality supplements for just pennies a day. Be mindful of added ingredients, like vitamins, so you don't unintentionally exceed tolerable intake limits for these.

· How should fish oil be stored? Store oils out of heat and light — refrigeration is a good idea, particularly for opened bottles of liquid fish oil (see Keep It Fresh).

· Which fish oil supplements are most like prescription omega-3 drugs? Some supplements have similarly high amounts and concentrations of EPA and DHA as found in prescription omega-3 drugs like Vascepa and Lovaza, but at lower cost. See how they compare.

· What are fish oil's side effects? Is fish oil safe? Although generally safe, high amounts of EPA and DHA may suppress the immune system. It's best to limit daily intake of EPA and DHA from supplements to no more than 2 grams, unless medically indicated. Fish oil may also thin the blood and slightly lower blood pressure. See Concerns and Cautions for more information. As mentioned, take fish oil with food to reduce fishy burps, a common side effect.

What It Is:

EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) are two principal fatty acids found in fish, krill, calamari, and green-lipped mussel. They belong to a family of nutrients known as omega-3 fatty acids. EPA and DHA can also be obtained from other marine sources, such as algae (algal oil). EPA and DHA are polyunsaturated fats ("good" fats, as opposed to saturated fats which are thought to increase the risk of heart disease). The body can only manufacture limited amounts of EPA and DHA from the essential fatty acid, alpha-linolenic acid (ALA) -- found in flaxseed oil, canola oil, soy oil and walnut oil. For more information about ALA see the separate review covering ALA and GLA products.

What It Does:

Heart Attack and Stroke:
The omega-3 fatty acids EPA and DHA have a number of potentially heart-healthy effects, including reducing triglyceride levels, slightly raising levels of HDL ("good") cholesterol, possibly, "thinning" the blood, reducing levels of homocysteine, and reducing blood pressure.

Furthermore, increased consumption of fish oils from fish and high levels of omega-3s in the blood have been associated with reduced risk of cardiovascular disease and related mortality (Mozaffarian, Ann Int Med 2013). The researchers indicated that the high blood levels could be achieved with average daily intake of a moderate amount of fish providing 250 mg to 400 mg of EPA plus DHA (see Getting EPA and DHA from Food, below) and noted that greater intake would not yield much further benefit. In line with this, the American Heart Association recommends consuming at least 1 to 2 fish servings (3.5 oz per serving), of non-fried, preferably oily fish, per week to reduce the risk of cardiac death, coronary heart disease, and ischemic stroke (the most common type of stroke). It notes that mercury contamination is a concern with some types of fatty fish (i.e. swordfish, tuna, etc.), but the "benefits of 1 to 2 servings a week outweigh the risks, especially if a variety of seafood are consumed." (Rimm, Circulation 2018).

Clinical trials since 2010 cast doubt on some of the cardiovascular benefits of fish oil supplements (Kwak, Arch Intern Med 2012; Hu, Arch Intern Med 2012; Bosch, NEJM 2012; Rizos, JAMA 2012; Chowdhury, BMJ 2012; Roncaglioni, NEJM 2013; AREDS2 Study, JAMA 2014). This was most recently demonstrated in the VITAL study, a 5-year study among a cross-section of older Americans. The VITAL study showed that supplementing with fish oil (460 mg of EPA and 380 mg of DHA daily) did not result in a lower incidence of major cardiovascular events than placebo. However, among people consuming less than 1.5 servings of fish per week, further analysis showed that the fish oil supplementation resulted in 19% and 40% reductions, respectively, in major cardiovascular events and heart attacks. In addition, African Americans had a 77% reduction in heart attacks with fish oil as compared to placebo (Manson, NEJM 2018). It should be noted, however, that a potential beneficial effect of the fish oil may have been masked in these trials by the fact that participants in most studies continued to take other heart medications and many participants already had significant intake of omega-3 fatty acids from fish in their diets.

Supplementation with fish oil may be helpful for people with chronic heart failure, as shown in a study of 31 men and women given 2,000 grams of an extremely concentrated fish oil (providing 920 mg DHA and 760 EPA) or placebo daily for two months. Compared to those given a placebo, the fish oil group experienced a 3% improvement in left ventricle ejection fraction (i.e., how well the heart pumps blood) and a 33% increase in flow-mediated dilation (which can be impaired by stiffness in the arteries). Supplementation also decreased global longitudinal strain by 8.3%, inflammation and fibrosis of heart muscle (i.e. ST2) by 2.16% and the ratio of early and late filling of blood in the heart (i.e. E/e') by 7.37% compared to placebo. The researchers noted that individuals who had the greatest improvements in left ventricle ejection fraction were those who began the study with lower levels of NT-proBNP, a peptide secreted by the heart when it has to work harder to pump blood (Oikonomou, Clin Nutr 2019).

There is some evidence that taking high dose fish oil may be beneficial during recovery from heart attack. In a study among 360 men and women who, in addition to standard lifestyle counseling and any required medications -- statins, beta- blockers, etc., began taking high-dose, purified fish oil (four one-gram capsules of Lovaza daily -- providing a total of 1,500 mg DHA and 1,860 mg of EPA) or a placebo within one month of hospitalization for a heart attack, the heart's ability to pump blood modestly improved after six months in those who took fish oil, while it worsened slightly in those who took the placebo (Heydari, Circulation 2016). There were no reports of bleeding (a potential concern with high-dose fish oil).

The American Heart Association has concluded that prescription n-3 FAs (EPA+DHA or EPA-only) at a dose of 4 grams/day (>3 grams/day total EPA+DHA) are an effective and safe option for reducing triglycerides as monotherapy or as an adjunct to other lipid-lowering agents (Skulas-Ray, Circulation 2019). However, be aware that not all prescription fish oils have shown the same benefits in reducing cardiovascular events, such as heart attack and stroke, in people with high triglyceride levels. For example, among people with high triglyceride levels, a high dose of Vascepa (a prescription fish oil highly concentrated for EPA rather than DHA) demonstrated a 25% reduction in the risk of initial heart attack, stroke or other major cardiac event in a five-year study, and a 30% reduction when subsequent cardiac events were counted. Vascepa was also shown to reduce coronary atherosclerosis progression among people with confirmed atherosclerosis and high triglyceride levels (see details for Vascepa). In contrast, a similar study with prescription Epanova (highly concentrated EPA + DHA) was halted due to a "low likelihood of demonstrating a benefit" (see details in Prescription Fish Oil vs. Supplements). Several theories have been generated to explain the difference in benefit seen with Vascepa versus Epanova, and a recent post-hoc analysis of data from the Epanova trial has found that some of these hypotheses may not be valid (see below for details).

Taking into consideration the findings of clinical trials, as well as the American Heart Association's latest recommendations, the bottom line on fish oil for cardiovascular and cerebrovascular disease is that eating non-fried fatty fish twice per week as part of a healthy diet continues to be recommended and may help to reduce the risk of cardiac death, coronary heart disease, and ischemic stroke. [See ConsumerLab's Canned Tuna and Salmon Review for comparisons of EPA and DHA in canned fish.] In addition, high-dose, high-concentration fish oil, such as from prescription fish oils, can be helpful to people with high triglyceride levels.

However, regarding fish oil supplements:

· There is no reliable evidence that fish oil supplements prevent heart disease in healthy people who are not at risk for heart disease.

· Research does not support fish oil supplementation for preventing heart attacks in people who have heart disease or who are at risk for heart disease unless they have recently had a heart attack. [High-dose fish oil, however, may provide added benefit to low-dose statin therapy in people with stable coronary artery disease (see Alfaddagh study below)].

· Research does not support fish oil supplementation for preventing stroke or atrial fibrillation. (Doses of 2 grams or more may actually increase the risk of atrial fibrillation.)

· Fish oil supplementation may help people with heart failure who have reduced left ventricular function.

· Fish oil supplementation, along with a high intake (3 or more servings per week) of fish may reduce the risk of venous thromboembolism.

· High-dose fish oil can help lower triglyceride levels in people with severe hypertriglyceridemia [including those whose triglycerides remain high while taking a statin (Kim, Clin Ther 2018)].

· Any other potential cardiovascular benefit of supplementation may be limited to people who do not regularly consume fish in their diets and who are not taking other medications for heart disease.

Consistent with the recommendations above, an analysis of 10 studies published from 1999 to 2014 involving 78,000 people with or at high risk for cardiovascular disease, found no significant association between supplementation with EPA and/or DHA and the occurrence of any major vascular events such as stroke, coronary heart disease, or death from coronary heart disease. It should be noted, however, that the analysis did not take into account the amounts of omega-3s people were already getting from their diets (Aung, JAMA 2018). Similarly, a much larger review of 79 clinical trials published from 1946 to 2017 involving over 112,000 people with or without cardiovascular disease concluded that taking omega-3 supplements does not reduce heart disease, stroke or death (Abdelhamid, Cochrane Database Syst Rev 2018). In addition, a major, long-term (7.4 year) study of adults with type 1 or type 2 diabetes showed no statistically significant cardiovascular benefit from a daily dose of 1 gram of fish oil (containing 460 mg EPA and 380 mg DHA) compared to a placebo (1 gram of olive oil): 8.9% and 9.2% of each group, respectively, experienced a serious vascular event (e.g., heart attack, stroke, transient ischemic attack) (ASCEND Study, NEJM 2018). In a separate arm of the study, patients were given low-dose aspirin (100 mg) or a matching placebo tablet each day, with 8.5% and 9.6% of each group, respectively, experiencing a serious vascular event, indicating a relative benefit with aspirin if not for the fact that it also caused significantly more major bleeding events (ASCEND Study, NEJM 2018). Although the two arms of the study were not compared, it is interesting to consider that the fish oil might have shown modest benefit if compared to the placebo tablet rather than to olive oil which, itself, may have some cardiovascular benefit, (particularly when substituted for saturated fat in the diet). Perhaps the largest and longest-term study of fish oil supplement use, involving 427,678 individuals in England, Scotland, and Wales followed for 8 to 9 years, showed that the 31.2% of the studied individuals who indicated taking fish oil supplements (dose not specified) had a 13% lower risk of dying, a 16% lower risk of death from cardiovascular disease, and a 7% lower risk of any cardiovascular event than the general population after adjusting for consumption of oily fish and other demographic differences. The researchers speculated that the reason why this study, as opposed to others, found positive associations, may have been its size and duration (Li, BMJ 2020).

On June 19, 2019, the FDA announced that it would not object to the use of a qualified health claim similar to the following for foods and dietary supplements containing at least 0.8 grams (800 mg) of EPA and DHA (combined total) per serving: "Consuming EPA and DHA combined may reduce the risk of CHD (coronary heart disease) by lowering blood pressure." An important caveat is that any such claim must be followed by "However, FDA has concluded that the evidence is inconsistent and inconclusive."

Use with statins:
Adding high-dose fish oil to statin therapy may help reduce the progression of coronary plaque and, not surprisingly, reduce high levels of triglycerides (as has been shown with high-dose fish oil alone).

A well-controlled 30-month study, however, found that taking a daily fish oil supplement in addition to low-dose statin therapy provided additional benefit in preventing progression of fibrous coronary plaque in people with stable coronary artery disease and well-controlled LDL levels, although there was not a similar benefit among people taking high-dose statins (at least 40 mg of atorvastatin, 20 mg of rosuvastatin, or 80 mg of simvastatin). Among low-dose statin users, fibrous plaque increased 5% in those not receiving fish oil, but it did not increase among those receiving fish oil (1,860 mg of EPA and 1,500 mg DHA, from 4 softgels of Lovaza). It also did not increase among those receiving high-dose statins. Musculoskeletal events, infectious diseases, and joint replacement were also significantly lower among those taking the fish oil (Alfaddagh, J Am Heart Ass 2017). Further analysis of the same study found that having an omega-3 index (a measure of EPA and DHA in the blood) of ≥ 4% appeared to guard against the progression of coronary plaque. In contrast, having an omega-3 index of ≤ 3.43% was predictive of the progression of plaque. However, among people with diabetes, higher blood levels of omega-3 were not found to prevent the progression of coronary plaque (Alfaddagh, Atherosclerosis 2019). This study also showed cognitive benefits.

A study in South Korea found that high-dose omega-3 supplementation significantly decreased triglyceride levels in those whose triglyceride levels remained elevated while taking a statin. In the study, men and women with high cholesterol and triglyceride levels received 20 mg of rosuvastatin daily. After one month, those whose triglyceride levels remained high (average 263 mg/dL) continued to take rosuvastatin plus either a high daily dose of omega-3s (1,520 mg DHA + 1,840 EPA) or placebo, for two months. Average triglyceride levels decreased by 26% among those who took the omega-3s and by only 2% among those who took the placebo (Kim, Clin Ther 2018). Similar results were found when the same dose of omega-3s was taken with atorvastatin. In men and women whose triglyceride levels remained above 200 mg/dL after one month of treatment with atorvastatin (20 mg daily), adding 1,520 mg DHA + 1,840 EPA daily for two months reduced triglyceride levels by an average of 26% compared to placebo (Jun, Diabetes Metab J 2019). (Note: Both studies were funded by Kuhnil Pharmaceutical Co., Ltd of South Korea.)

Another study in South Korea, among 159 men and women (average age 60), found that those who took a combination of 4,000 mg of omega-3 fatty acid ethyl esters and 40 mg of atorvastatin per day for two months had an average decrease in triglyceride levels of 18.5% compared to a slight increase in triglyceride levels of 0.9% with atorvastatin alone. There were no significant changes in total, LDL or HDL cholesterol with omega-3 supplementation compared atorvastatin alone. The treatments were provided by Korea United Pharm Inc, which funded the study (Woo, Clin Ther 2021).

Insulin Sensitivity and Blood Sugar Control:
Limited evidence suggests that fish oil can modestly improve insulin sensitivity (note, a study of krill oil suggested a negative effect). A placebo-controlled study in Australia among 68 overweight and obese men and women (average age 51), most of whom had hyperinsulinemia, impaired fasting glucose, or high cholesterol, but none had diabetes, found that 1 gram of fish oil (EPAX1050 -- 460 mg DHA + 60 mg EPA) taken twice daily with meals for three months modestly reduced fasting insulin by an average of 1.62 µIU/L and improved insulin resistance (as measured by HOMA-IR) by - 0.40 units compared to a placebo (corn oil). Fish oil did not decrease fasting glucose, total or LDL cholesterol, or increase HDL cholesterol compared to placebo (Abbott, Prostaglandins Leukot Essent Fatty Acids 2020). Further analysis of the same study showed that fish oil supplementation also significantly increased total testosterone levels in men, but not in women (see details below).

An 8-week pilot study in Brazil among 32 overweight and/or obese adults with type 2 diabetes given a larger dose of fish oil (4 grams daily) suggests a benefit. Participants showed improved insulin sensitivity, reduced triglycerides, and increased HDL. However, the results are preliminary as there was no control group. Participants consumed Nature's Bounty 2,400 mg providing 1,440 mg EPA and 960 mg DHA from two capsules taken with food and water in the morning and in evening -- a total of four capsules daily) (de Souza, J Diab Complications 2020).

A small study of healthy overweight/obese adults in Norway showed that consuming five ounces of fatty fish (salmon: 13% fat) five times per week for dinner for 8 weeks significantly improved blood sugar regulation (i.e., smaller increases in blood sugar) measured two hours after a meal, whereas lean fish (cod: 1% fat) did not. Neither type affected fasting blood sugar levels, and a previous study of healthy, young normal-weight adults showed no effect of either on blood sugar control (Helland, Br J Nutr 2017).

Arthritis and Other Inflammatory Diseases:
Increased intake of the omega-3 fatty acids in fish oil alter the body's production of substances known as prostaglandins, and, consequently, reduce some forms of inflammation. On the basis of this, EPA and DHA have been tried in the treatment of symptoms of rheumatoid arthritis with considerable success (especially in early stages of the disease). Unlike "disease modifying" drugs, however, fish oil probably doesn't slow the progression of the disease. A study of several thousand women in Sweden found that consistent, long-term term intake averaging more than 210 mg per day of omega-3 fatty acids from eating fish was associated with a 52% lower risk of developing rheumatoid arthritis compared with lower intakes over the period of the study -- about 7.5 years (Di Giuseppe, Ann Rheum Dis 2013). This level of intake is equal to at least one serving per week of a fatty fish, such as salmon, or four servings per week of lean fish, such as cod. The study could not adequately assess the impact of supplement use due to limited use of supplements in the study population. An analysis of twenty-two clinical studies also concluded that marine oils can reduce pain associated with rheumatoid arthritis -- but not joint function. The results indicated that it may be best to use a product with at least 50% more EPA than DHA, but an ideal dose could not be determined (Senftleber, Nutrients 2017).

Despite the suggestion, above, regarding the importance of EPA, a later study found DHA alone to be somewhat helpful. In the study, 38 men and women with rheumatoid arthritis consumed either DHA-enriched food (providing 2,100 mg of DHA per day from 8 grams of microalgae oil) or food enriched with a placebo (8 grams of sunflower oil providing 4,700 mg of linoleic acid -- an omega-6 fatty acid) for ten weeks. It found that consuming the DHA-enriched food caused a statistically significant decrease in the average number of tender and swollen joints (from about 14 to 10), while consuming sunflower oil-enriched food increased the number of tender and swollen joints (from about 10 to 12). However, neither the DHA nor sunflower oil changed biochemical measures of inflammation (ESR and CRP) or patients' self-assessments of their conditions (Dawczynskia, Clin Nutr 2017).

Most studies have not found fish oil supplementation to reduce pain associated with osteoarthritis (Senftleber, Nutrients 2017; Boe, Am J Orthop (Belle Mead NJ) 2015). However, researchers who analyzed data from a placebo-controlled study of older, sedentary, obese women and men (ages 50 to 80) in Australia who were not large consumers of fish or fish oil and had mild, chronic osteoarthritis pain (in the knees, lower back and/or shoulders) found that supplementation with 1,000 mg of DHA and 200 mg EPA (triglyceride forms) taken with breakfast and, again, with dinner reduced average self-reported overall pain by 42% compared to no treatment with fish oil. Interestingly, taking curcumin (Longvida, providing 160 mg of curcumin) daily in addition to the fish oil provided less pain relief than the fish oil alone (Kuszewski, Rheumatol Adv Pract 2020).

High doses of omega-3 fatty acids (1,860 mg of EPA and 1,500 mg of DHA daily from 4 softgels of Lovaza) taken for one year by adults with coronary artery disease resulted in no worsening of arthritic pain, stiffness, or physical function while all of these worsened in a similar control group not supplemented with fish oil. In contrast to the control group, the group given Lovaza reported more exercise per week (197 minutes vs. 135 minutes) and less joint replacement surgery (0% vs. 3.1%) (Alfaddagh, J Clin Lipidol 2018 -- additional results from this clinical trial are reported above as Alfaddagh, J Amer Hearth Assoc 2017).

Due to its anti-inflammatory effects, fish oil is sometimes promoted for gout -- painful joint inflammation caused by elevated blood levels of uric acid. Preliminary research suggests the omega-3 fatty acids EPA and DHA may inhibit the inflammatory response involved in this form of arthritis (Yan, Immunity 2013). In men, higher blood levels of omega-3 fatty acids (>0.46 mmol/L) have been associated with a lower recurrence of acute gout attacks (Abhishek, Ann Rheum Dis 2016). According to an observational study among men and women who experienced gout, consuming fish rich in omega-3 fatty acids was associated with a protective effect against recurrent attacks, but taking fish oil supplements (fish oil, cod liver oil or omega-3 fatty acid supplements) did not have this effect (Zhang, American College of Rheumatology Annual Meeting 2015). However, people with gout are advised to limit intake of seafood such as sardines, mackerel and herring (common sources of fish oil in supplements) because these fish contain high levels of purines, compounds known to increase uric acid levels in the blood (American College of Rheumatology 2012; Kaneko, Biol Pharm Bull 2014). Purines are generally thought to be eliminated by purification and distillation during the manufacturing of fish oil, although one small study found substantial amounts of purine in two fish oil supplements (one cod liver oil supplement and one supplement derived from sardines) (Roy, Food Nutr Sci 2013). In short, eating fish low in purines may be helpful for people with gout, but there is no evidence that taking fish oil supplements is helpful.

The anti-inflammatory effects of EPA and DHA have also caused researchers to investigate possible benefits of fish oil for the treatment of menstrual cramps, inflammatory bowel disease (ulcerative colitis and Crohn's disease), lupus, and IgA nephropathy. For each of these conditions, at least one double-blind study has found positive results. A large European study (Hart 2009) showed that people with the highest consumption of DHA (410 mg to 2,000 mg per day) had a 77% reduction in the risk of developing ulcerative colitis over an average period of four years than those consuming the lowest amount (up to 110 mg per day). Conversely, those consuming the most (15 to 35 grams per day) of linoleic acid (an omega-6 fatty acid) were 2.3 times as likely to develop the disease as those consuming the lowest amount (8 grams - 11 grams per day). In a study in which people with stable ulcerative colitis were given 1,000 mg twice daily of EPA for 6 months, 76.7% remained in remission versus 50% of those given placebo. Levels of fecal calprotectin, a marker of mucosal inflammation, were also significantly reduced in 63.3% of those given EPA versus only 13.3% of those given placebo. The EPA was taken as enteric-coated capsules (in order maximize intact delivery into the small intestine), each containing 500 mg of EPA in the free fatty acid form (ALFA, from SLA Pharma AG — apparently not currently sold in the U.S.) (Scaioli, Clin Gastro Hep 2018). However, in Crohn's disease, a trial of four grams per day of omega-3 fatty acids (50-60% EPA and 15-25% DHA) was ineffective at preventing relapses.

Supplementing with fish oil may help alleviate symptoms of dry eye (an inflammatory condition also known as keratoconjunctivitis sicca), but so might other fatty acids. The largest and longest study to date, conducted by the University of Pennsylvania and the National Eye Institute, involved giving fish oil or olive oil (intended as a placebo) to several hundred men and women with moderate to severe dry eye for 12 months. Symptoms and signs of dry eye improved among patients receiving fish oil treatment (providing 2,000 mg of EPA and 1,000 mg of DHA in the triglyceride form daily) and among those who received a similar amount of olive oil, with the disease severity score improving by about 13 points out of 100, although there was slightly greater improvement in the fish oil group (Asbell, N Engl J Med 2018).

Several shorter-term studies suggest that fish oil supplementation in combination with other fatty acids and/or vitamins may help. This was shown in a study of postmenopausal women in the U.S. with dry eye who took a formula consisting of fish oil with black currant seed oil and vitamins for six months (Sheppard, Cornea 2013). The daily dose given (4 softgels) provided fish oil (126 mg EPA and 99 mg DHA) and 1,570 mg of black currant seed oil (consisting of 240 mg GLA, 196 mg ALA, 710 mg of LA) in a formula (HydroEye) which also provided vitamins A, B6, C, and E. (Note: The amounts of fatty acids in the product during the study are slightly higher than listed on the HydroEye label, but are within reasonable variation.) A large study of young adults found that taking a fish oil capsule twice daily (each capsule providing 180 mg EPA and 120 mg DHA) improved symptoms of dry eye associated with computer use. The fish oil significantly decreased the rate of tear evaporation. The study was conducted in northern India which has a largely vegetarian diet and low consumption of fish (Bhargava, Contact Lens & Ant Eye 2015). A study among 105 men and women diagnosed with mild to moderate dry eye found those who took 4 softgels containing re-esterified (triglyceride form) fish oil (providing a total daily dose of 1,680 mg of EPA and 560 mg of DHA) (PRN Dry Eye Omega Benefits, Physician Recommended Nutriceuticals) daily for 3 months had modest improvements in symptoms of dry eye, such as soreness, grittiness and sensitivity to light, and decreased dryness (as measured by tear osmolarity), compared to those who took a daily dose of linoleic acid (3,136 mg) (Epitropoulos, Cornea 2016). [Note: The label for this product, which is sold in the U.S., indicates that it also contains 1,000 IU of vitamin D₃].

Fish oil supplementation has also been found to be helpful for dry eye associated with wearing contact lenses. A study in Australia among 65 adults who experienced dry eye and discomfort from daily use of soft disposable contact lenses found that fish oil capsules (providing 900 mg of EPA and 600 mg of DHA daily) taken for three months significantly reduced self-reported symptoms of dry eye compared to those who took a placebo (olive oil capsules providing 1,500 mg olive oil per day) or capsules containing a combination of fish oil and flaxseed oil (providing 900 mg of EPA, 600 mg of DHA and 900 mg of ALA per day). Fish oil supplementation also decreased certain markers of eye inflammation just as well as anti-inflammatory corticosteroid eye drops but took much longer to have this effect (three months vs. two weeks). The study also found that fish oil eye drops given four times daily (providing a total of 30 mg of EPA and 3 mg of DHA to each eye per day) for three months decreased certain markers of eye inflammation but did not reduce self-reported symptoms of dry eye compared to taking fish oil capsules (Downie, Invest Ophthalmol Vis Sci 2018).

Liver disease:
Small clinical trials suggested that fish oil supplementation might reduce liver fat or improve liver function in people with nonalcoholic fatty liver disease (NAFLD) (Lu, Gastroenterol Res Pract 2016).

A larger study among 167 adults with early-stage NAFLD found that taking fish oil capsules providing 1,140 mg of DHA and 1,380 mg of EPA (as Hepaxa from BASF) daily for 5 ½ months did not decrease liver fat compared to placebo (olive oil). In fact, both groups had similar decreases in the percentage of liver fat by the end of the study (a decrease of 26% and 28%, respectively), and those taking the placebo had greater improvements in certain liver enzymes than those taking Hepaxa. Although the researchers reported an association between increased levels of EPA + DHA (from the fish oil) in red blood cells and overall reduction in liver fat, they did not analyze this finding to determine if it was statistically significant (Tobin, Nutrients 2018). Despite the results, BASF, which funded the study, and Hepaxa's U.S. distributor (DIEM Labs) promoted Hepaxa as "clinically proven" to reduce liver fat in people with NAFLD. Both companies agreed in 2021 to pay a fine to settle FTC charges of deceptive advertising.

Asthma:
Although giving fish oil to pregnant women has been shown to decrease the incidence of asthma in their offspring, it does not appear to help people who already have asthma. A study in the U.S. among 98 overweight/obese children and young adults ages 12 to 25 with poorly-controlled asthma found a high daily dose of highly-concentrated fish oil (providing 3,180 mg EPA, 822 mg DHA and 101 mg other omega-3 fatty acids -- from Nordic Naturals) for 24 weeks did not improve measures of lung function or decrease exacerbations requiring urgent medical care and/or systemic corticosteroid medication compared to placebo (Lang, Ann Am Thorac Soc 2019). As noted elsewhere, a green-lipped mussel oil product has shown mixed results for asthma.

Cancer:
Prevention:
Some research suggests that consuming fish or taking fish oil supplements may reduce the risk of precancerous colorectal growths in people with low blood levels of omega-3s and reduce the risk of dying from colorectal cancer. However, not all studies with supplementation have found a benefit.

Daily supplementation with fish oil (460 mg of EPA and 380 mg of DHA) plus vitamin D3 (2,000 IU) was not shown to reduce the risk of cancer of any type in a major, 5-year, placebo-controlled study among over 25,000 of older Americans (average age 67) in the VITAL study (Manson, NEJM 2018). However, further analysis of data from the same study found that supplementation significantly reduced risk of precancerous colorectal growths (adenomas and polyps) by 41% in African Americans and by 24% in individuals who began the study with low blood levels of EPA and DHA (i.e. an omega-3 index of < 2.5%) (Song, JAMA Oncol 2019). Other research has shown that people diagnosed with colorectal cancer who then consume at least 300 mg per day of omega-3 fatty acids from fish and/or fish oil products have a 41% lower risk of dying from the disease than people consuming less than 100 mg per day (Song, Gut 2016).

It has been suggested that the anti-inflammatory effects of omega-3 fatty acids might reduce the risk of colorectal cancer by slowing the rate at which cells that line the colon reproduce or by offsetting the inflammatory effects of arachidonic acid, a fatty acid that may promote tumor growth. However, a study among 126 men and women (average age 58) with a history of colorectal adenomas (benign tumors that can become cancerous) who took 3 capsules per day of the highly concentrated prescription fish oil (Lovaza, providing a total daily dose of 1,395 mg EPA plus 1,125mg DHA) for six months found that the fish oil did not affect the rate of colorectal cell replication or cell death compared to placebo (olive oil). This was true regardless of whether or not participants had a genetic variant associated with increased tissue levels of arachidonic acid (Murff, Nutr Cancer 2021).

Eating fish is associated with a lower risk of recurrence, and risk of death, from breast cancer. In women with early stage breast cancer, higher intakes of DHA and EPA from fish (>73 mg/ day DHA+EPA) have been associated with a 25% lower risk of breast cancer recurrence (Patterson, J Nutr 2011). Another study found that over a 15 year period, women with primary in situ or invasive breast cancer who consumed the most tuna and/or other baked/broiled fish had a 25% to 34% reduction in risk of death from all causes, compared to those who reported eating no fish (Khankari, Cancer 2015). A study among postmenopausal women found that current use (but not past use) of fish oil supplements was associated with a 32% reduction in the risk of breast cancer. Risk was greatly reduced for ductal carcinoma of the breast (the most common form of breast cancer), but not lobular carcinoma (Brasky, Canc Epidemiol Biomarkers Prev 2010). It is speculated that the anti-inflammatory property of fish oil may be responsible for an anti-cancer effect because chronic inflammation is associated with cancer initiation and progression.

There is mixed evidence as to whether fish oil and omega-3 fatty acids help prevent prostate cancer. One study found no association between fish consumption and the development of prostate cancer although it found a large reduction in deaths from prostate cancer (Szymanski, Am J Clin Nutr 2010). A 6-year study of men who self-reported taking fish oil supplements also found no association between fish oil use and the development of prostate cancer (Brasky, Nutr Cancer 2011). However, some studies that did not look directly at the consumption of fish or fish oil but at the ratios of fatty acids in blood serum, have found some unexpected associations with prostate cancer: One study of this kind found that men with the highest levels of DHA plus EPA and DPA (another omega-3 fatty acid) were 44% and 71%, respectively, more likely to develop low-grade and high-grade prostate cancers compared to men with the lowest levels (Brasky, JNCI 2013). This report included an additional analysis of several other blood-based studies, most of which, but not all, also showed associations between fatty acids in fish oil (particularly DHA) and development of prostate cancer (particularly high-grade cancer). However, whether or not there is a cause-and-effect relationship between intake of fish oils and prostate cancer is still not known. In fact, it has been suggested that the relationship with prostate cancer could stem from toxins in fish meat or introduced from frying or overcooking fish (Aucoin, Integr Canc Ther 2017).

Chemotherapy:
Fish oil may prevent weight loss during cancer chemotherapy. Although some trials have not shown a benefit, one study (Murphy, Cancer 2011) showed significant benefit. In this study, patients with non-small cell lung cancer took fish oil throughout initial chemotherapy (approximately 10 weeks). During the course of chemotherapy, patients who did not take fish oil experienced an average weight loss of 5 lbs (of which approximately 2.2 lbs. was muscle). Those taking fish oil had, on average, no change in weight despite having lost, on average, 6.3% of their weight over the previous 6 months. In fact, many of those taking fish oil increased their muscle mass — with the greatest increases corresponding to the greatest increases in plasma EPA concentrations. Cancer response rates to the chemotherapy were similar in the two groups. Patients taking the fish oil were given an option consuming either four 1-gram gelatin capsules per day or 7.5 mL of liquid fish oil per day. Both formulations provided 2.2 grams of EPA per day. 

However, some recent research suggests that fish oil (from supplements as well as fish) may interfere with chemotherapy. A fatty acid naturally found in fish oil known as 16:4(n-3) and into which other fatty acids, such as EPA, are converted in the body, has been shown in mice to activate white blood cells leading to resistance to chemotherapy. It is, therefore, advised to temporarily avoid fish oil from the day before chemotherapy until the day thereafter, as well as herring and mackerel (which raise 16:4(n-3) levels more than other fish such as salmon and tuna) in the 48 hours surrounding chemotherapy (Daenen, JAMA Oncology 2015).

Eye Disease:
As explained below, consuming EPA and DHA from the diet (fish) is associated with lower risk of eye disease. However, taking EPA and DHA as supplements has not shown benefit.

Analyses of dietary intakes taken as part of the Age-Related Eye Disease Study (AREDS) show that participants who reported the highest intake of EPA and DHA were 30% less likely to develop diseases of the retina -- neovascular age-related macular degeneration (AMD) and central geographic atrophy (CGA) -- compared to those with the lowest intake (SanGiovanni, Am J Clin Nutr 2009). Decreased risk of developing AMD was also shown in a study of over 30,000 female health professionals: Those consuming at least one serving per week of fish had a 42% reduction in risk of developing AMD compared to those eating less than one serving per month — and the benefit was greatest with canned tuna or dark-meat fish (e.g., mackerel, salmon, sardines, bluefish, and swordfish) (Christen, Arch Opthamol 2011). Analyzed another way, the risk of developing AMD in this study was reduced by 38% and 36%, respectively, among those with the highest intakes from their diets of DHA (230 mg median intake) and EPA (100 mg median intake) compared to those consuming the least amount (median intakes of 60 mg of DHA and 10 mg of EPA). Based on these observations, EPA and DHA were included in the large AREDS2 (Age-Related Eye Disease Study 2) which evaluated a combination of supplements for preventing the progression of AMD. However, the addition of 350 mg DHA and 650 mg EPA to a combination vitamin A (from beta-carotene), vitamin C, vitamin E, zinc, and copper did not offer any additional benefits for slowing progression of AMD (AREDS2 Res Grp, JAMA 2013). See the Review of Eye Health Supplements for more information about AREDS and AREDS2.

Similarly, a five-year, placebo-controlled study of over 15,000 men and women (average age 67) (who were participants in the larger VITAL study) showed that daily supplementation with fish oil (providing 460 mg of EPA and 380 mg of DHA) plus vitamin D3 (2,000 IU) did not reduce the risk or slow the progression of AMD (Christen, JAMA Ophthalmol 2020).

A long-term observational study among 3,482 older men and women (average age 67) with type 2 diabetes found that those who reported consuming approximately 500 mg of EPA+ DHA from foods on a weekly basis were 46% less likely to develop sight-threatening diabetic retinopathy during the six-year study than those who consumed less this amount from their diet (Sala-Vila, JAMA Opthamol 2016). Even greater reductions in risk were observed among those who had advanced diabetes or who also had high blood pressure. The researchers noted that this amount of EPA + DHA can be met by consuming the American Heart Association's recommendation of two serving of fish (preferably oily fish) per week.

Depression:
Many studies have evaluated fish oil for depression. Most have shown a benefit, but some have not. Those that have shown a benefit have tended to use large doses (about 1,500 mg to 3,500 mg per day of omega-3 fatty acids) containing more EPA than DHA and often in populations not already getting much fish oil from their diets. In fact, treatment of depression using high-dose omega-3s containing more than 50% EPA was shown to have the strongest evidence of benefit of any type of supplement used for treating mental disorders according to an analysis of 33 meta-analyses. The evidence was particularly strong for use in conjunction with SSRI medication (Firth, World Psych 2019).

In 2019, the International Society for Nutritional Psychiatry Research issued clinician guidelines stating that in individuals with major depressive disorder, supplementing with omega-3s (1 to 2 grams per day for at least 8 weeks of either pure EPA or a combination of EPA + DHA in a ratio of > 2:1) can accelerate the effects of an antidepressant when started at the same time as the antidepressant, as well as enhance the effects of an antidepressant when results have been inadequate. The guidelines state that clinicians should consider relevant physical conditions, including fish hypersensitivities, before treatment with omega-3s is started, and monitor for common side effects as well as for potential adverse effects with high doses of fish oil, such as higher fasting blood sugar and increased LDL cholesterol (Guu, Psychother Psychosom 2019).

In adults:
A study of depressed older women in a nursing home setting showed that after taking high-dose omega-3 fatty acids for eight weeks (2,500 mg once daily consisting of 1,670 mg EPA and 830 mg DHA), 40.9% had a remission of depression compared to 16.7% of those taking placebo (Rondanelli, J Am Col Nutr 2010). This study also found a statistically significant improvement in the self-assessed quality of life and that the fish oil treatment was well tolerated. In another study, the combination of EPA plus the prescription antidepressant fluoxetine (Prozac) was better than either EPA or fluoxetine alone for treating major depression in a short-term (8-week) study of 60 people. However, a study of people with congestive heart failure and depression failed to show any additional benefit from EPA (930 mg) and DHA (750 mg) daily when added to treatment with the prescription antidepressant sertraline (Zoloft) (Carney, JAMA 2009).

The best evidence for omega-3's has been in cases of major and moderate depression, but not mild depression, and one group of researchers has concluded that the antidepressant benefit is strongly dependent upon the EPA content of the supplement. After pooling and reviewing studies using a total of 1,000 mg to 6,000 mg of EPA and DHA, those in which EPA was 60% or more of the total showed a highly significant improvement, whereas those that were less than 60% EPA did not (Martins, Molec Psy 2012). An analysis of eight clinical studies which investigated the effects of taking EPA and/or DHA from fish oil with various anti-depressants (including SSRI drugs such as fluoxetine and sertraline and tricyclic drugs such as amitriptyline) found that, overall, there appeared to be additive benefit, especially from EPA in doses of about 1,000 mg to 2,000 mg per day, concluding, "EPA-rich omega-3 fish oil may be recommended for the adjunctive treatment of major depressive disorder." (Sarris, Am J Psychiatry 2016). Other researchers, however, believe that any benefit is, at best, small to negligible (Bloch, Molec Psy 2012). Nevertheless, further analysis of blood samples from the study by Rondanelli (above) found that elderly depression is characterized by very low levels of omega-3s, in particular EPA, in red blood cell membranes compared to those in healthy individuals and that EPA-rich supplementation restored EPA concentrations to normal values (Rizzo, Nutr J 2012). Interestingly, an earlier study using 1,000 mg, 2,000 mg, or 4,000 mg of EPA found that only the group receiving 1,000 mg had a significantly better outcome than a group receiving placebo (Peet, Arch Gen Psychiatry 2002).

A small study among young adults (average age 20) with mild to moderate depression but not taking antidepressant medication, found that those who took two fish oil capsules (providing a total of 1,000 mg EPA and 400 mg of DHA ) daily for 21 days had significantly improved self-reported depression scores compared to those who took a placebo. At the end of the study, 67% of those who took EPA and DHA were no longer clinically depressed, compared to 20% in the placebo group (Ginty, Psychiatry Res 2015). It's worth noting that the amount of EPA given and ratio to DHA are consistent with those suggested by earlier research for treating depression.

A possible explanation for moderate improvements in depression among those who respond to fish oil, is that fish oil increases white matter (myelinated fibers that connect brain cells) in areas of the brain which can be compromised in depression. A small study of 16 acutely depressed adults with major depression found that among the 5 whose depression improved over the 6-week period of taking 4 grams of fish oil daily (OmegaLife-3, Unicity International, Inc., providing 1,600 mg of EPA and 800 mg DHA), 80% had increases in white matter in key brain regions, compared to only 45% of those whose depression did not improve (Chhetry, J Psychiatr Res 2016).

In adolescents and children:
A benefit with fish oil was found in a small study in Slovakia among children and adolescents (average age 15) with depression. The children took fish oil (providing 1,000 mg EPA and 750 mg DHA) or a placebo (linoleic acid from sunflower oil) daily for three months. Most of the children in both groups were continued on SSRI antidepressants (sertraline, fluvoxamine or fluoxetine) throughout the study. Severity of depression symptoms was reduced by an average of 25% in those who took fish oil, compared to only 9% among those who took the placebo. However, the fish oil was not effective in those with mixed depression and anxiety (Trebaticka, Child Adolesc Psych Ment Hlth 2017). It's interesting to note that the fish oil used in this study is roughly in-line with what has been most likely to work in other studies: It provided 1,000 mg of EPA, which was nearly 60% the omega-3 content.

A 10-week study in New York of adolescents (aged 12 to 19 years) with moderate to severe major depressive disorder and not taking antidepressants found that both fish oil and a placebo (soybean and corn oil providing mainly omega-6 fatty acids) were equally effective at decreasing depression severity (about 40% to 50% of the participants in each group improved), although fish oil was not superior to placebo. However, participants reported consuming eight servings per week of foods high in omega-3 fatty acids, such as fish, i.e., they were generally not lacking intake of omega-3 fatty acids. The daily dose of omega-3s from fish oil (which was 67% EPA and 33% DHA) began at 1,200 mg but, if not effective, was increased during the study, such that ending doses averaged 3,200 to 3,400 mg of omega-3's or placebo (Gabbay, J Clin Psychiatry 2018).

Suicide:
An analysis of blood samples from 1,600 military personnel showed those who committed suicide had, prior to suicide, significantly lower blood levels of DHA than personnel who did not commit suicide (Lewis, J Clin Psychiatry 2011). The population studied was predominantly male and the risk of suicide was found to be 62% greater among men with levels of serum DHA below 1.75% (% of total serum fatty acids) compared to those with higher levels. There was no such relationship with EPA levels. The researchers note that omega-3 fatty acid levels were generally low across the military personnel in the study, much lower than in the general population, and suggested that even greater risk reductions could be possible with higher serum levels of DHA.

Anxiety:
Fish oil supplementation was associated with a modest improvement in anxiety symptoms among people with a clinically diagnosed neuropsychiatric or major physical illness, according to an analysis of 19 controlled clinical trials. The association was weaker in people without a diagnosed disease and it was greater when the dose was 2,000 mg or more of EPA and DHA per day and the ratio of EPA/DHA was less than 60% (Su, JAMA Network Open 2018). Among the studies analyzed was one of U.S. medical students that showed, over 12 weeks, that those who received high-dose omega-3 fatty acids (2,496 mg once daily providing 2,085 mg EPA and 348 mg DHA) had a 20% reduction in anxiety symptoms compared to those receiving placebo treatment. Treated students also had a 14% decrease in a marker of inflammation (stimulated IL-6 production) (Kiecolt-Glaser, Brain Behav Immun 2011). The study intentionally used an extremely concentrated fish oil (supplied by OmegaBrite) high in EPA due to earlier evidence that EPA has relatively stronger anti-inflammatory and antidepressant effects than DHA.

Stress:
Fish oil may slightly blunt some responses to mental stress, according to a study of young men and women given a large amount of fish oil (9 grams daily providing 1,600 mg EPA and 1,100 mg DHA) for eight weeks. When the participants were asked perform math calculations as quickly as possible for 5 minutes (a mental stress test), the mean heart rate increased by three beats less per minute after fish oil therapy than when the test had been taken at the beginning of the study, before therapy. The increase in total nervous activity (measured by nerve activity in the leg) was also significantly less after fish oil therapy. A control group, given olive oil instead of fish oil, did not have these reductions in heart rate and nervous activity (Carter, Am J Physiol 2013). However, in another study, fish oil was not found to be helpful. In the study, 90 men and women in Australia with self-reported chronic moderate to high levels of work stress took four capsules daily of predominately EPA fish oil (4 grams daily providing 2,200 mg of EPA and 440 mg of DHA) for three months. Those taking the fish oil did not experience reductions in psychological stress compared to those taking placebo (olive oil) (Bradbury, Front Pharmacol 2017). There was also no improvement in other measures of stress, such as the ratio of cortisol to DHEA and levels of inflammatory cytokines.

Migraine Headache:
Getting more fish oil from the diet may reduce headache frequency in adults with migraine, with greatest benefit observed when intake of omega-6 fatty acids is also reduced. A study among 141 adults with chronic or episodic migraine showed that following a diet aimed at providing 1,500 mg of the omega-3 fatty acids EPA+DHA from fish daily, with or without reducing intake of linoleic acid (an essential fatty acid found in foods containing oils from corn, sunflower, safflower, soy, peanut and other plants, including flaxseed), decreased total headache hours per day by 1.7 and 1.3 hours, respectively, compared to following a diet providing little (less than <150 mg) of EPA+DHA daily. Increasing intake of omega-3 fatty acids and decreasing intake of linoleic (to about 3.2% of energy intake) decreased headache days per month by two days more than only increasing intake of omega-3 fatty acids. Both fish oil diets increased blood levels of 17-hydroxydocosahexaenoic acid (17-HDHA), a derivative of DHA with pain-relieving effects. However, neither of the fish oil diets significantly affected levels of other pain and inflammatory mediators with more established links to headaches (such as prostaglandin E2, leukotriene B4, cysteinyl leukotrienes, or calcitonin gene related peptide) (Ramsden, BMJ 2021).

Fish oil supplements may also help reduce the frequency of migraine headaches, although the evidence is mixed. Based on positive findings of some small, early studies, a placebo-controlled study involving 183 migraine patients was conducted in France in which roughly half the patients received 6 grams of fish oil daily for 16 weeks and the other half received a placebo. During this period, 55% and 45% reductions in migraine attacks occurred, respectively, in the fish oil and placebo groups, indicating a strong placebo effect and a modest fish oil effect. However, the primary end-point of the study was the effect during only the last 4 weeks of treatment and, during that time, there was no statistically significant difference in the number of attacks between the two groups (Pradalier, Cephalalgia 2001). A placebo-controlled study of 60 migraine patients in Brazil found a significant benefit from giving fish oil containing 400 mg EPA plus 350 mg DHA twice-a-day before meals. For ethical reasons, the fish oil and placebo groups also received a low daily dose (10 mg) of amitriptyline (an antidepressant helpful for migraine). During 8 weeks of treatment, 66.7% of those given fish oil achieved an 80% reduction in the number of days of headache while only 33.3% of those given placebo achieved this level of reduction — a statistically significant difference (Soares, Nutr Neurosci, 2017).

Psychosis and Schizophrenia
A year-long study in adolescents and young adults (ages 13 to 25) identified as at risk for developing psychosis or schizophrenia found those who took 700 mg EPA plus 480 DHA from fish oil daily for 3 months were much less likely to develop a psychotic disorder in the nine months following treatment compared to those who had taken a placebo: Among those who took the EPA and DHA, 4.9% developed psychosis compared to 27.5% of those in the placebo group (Amminger, Arch Gen Psychiatry 2010). In a follow-up study approximately 7 years after the original treatment with EPA and DHA, only 10% had developed psychosis, compared to 40% among the placebo group. Those who took the fish oil had significantly higher measures of psychosocial functioning and required less medication than those who took the placebo. The researchers speculated that omega-3 supplementation may be especially effective during adolescence, when the brain is still undergoing significant development (Amminger, Nature Communications 2015).

A study in Poland among first-episode schizophrenia patients (ages 16 to 35) found a small to moderate benefit from taking fish oil in addition to regular medication. During 26 weeks of taking four capsules daily of concentrated fish oil (providing a daily total of 1,320 mg of EPA and 880 mg of DHA) rather than a placebo containing olive oil, 69.4% experienced at least a 50% improvement in symptom severity while only 40% of those given the placebo experienced this level of improvement. The greatest improvements were in depressive symptoms. The researchers noted that studies of fish oil in people with chronic (long-term) schizophrenia have shown mixed results, suggesting that fish oil may be more effective at early stages of the disease (Pawelczyk, J Psych Res 2016).

While fish oil supplementation may provide the benefits noted above, an international, placebo-controlled study found no benefit when adding it to cognitive behavioral case management (CBCM) for adolescents and young adults at high risk for psychotic disorders. During the first six months of the study, subjects were given up to 20 sessions of CBCM and, each day, took four capsules of highly concentrated fish oil providing a total of 840 mg of EPA and 560 mg of DHA. Antipsychotic medication was not given, but antidepressant and anti-anxiety medication was permitted. Although a lower than expected percentage of subjects developed psychosis during the study, the percentage was not significantly different between those given the fish oil and those given placebo (paraffin oil). Over a full year (including six months after fish oil and regular CBCM treatment ended), about 11% of both the fish oil and placebo groups had progressed to psychosis. (McGorry, JAMA Psychiatry 2016)

Epilepsy:
Omega-3 fatty acids inhibit neuronal excitability and reduce seizures in animal models, but, at high doses (1,700 mg to 2,200 mg of EPA + DHA daily), have failed to reduce seizures in people with drug-resistant epilepsy. However, a small, but well-controlled study using a lower dose (1,080 mg of EPA plus DHA per day) for 10 weeks found a 33.6% reduction in seizure frequency compared to placebo. A higher dose (twice the dose) was also tested but was not effective. The fish oil used in the study, which was funded by the National Institutes of Health, was Nature Made Fish Oil 360 mg OMEGA-3. The lower dose consisted of three gel capsules per day (each capsule containing 216 mg of EPA and 144 mg of DHA), while the higher dose was six capsules per day. During treatment with low-dose, patients had an average of 12.18 seizures per month, compared to 17.67 and 18.34 seizures per month, respectively, with the high-dose and placebo (DeGiorgio, J Neurol Neurosurg Psychiatry, 2014). The study authors note that a potential reason why the lower dose was more beneficial than higher dose is that high-doses of fish oil may cause excessive reductions in non-esterified fatty acids (e.g., arachidonic acid), and that a study of fish oil in depression found a similar benefit using low-dose, but not higher-dose fish oil (Peet, Arch Gen Psychiatry 2002).

Attention Deficit/Hyperactivity Disorder (ADHD) and Executive Functioning In Children/Adolescents:
Studies using fish oil supplements in treating ADHD have yielded conflicting results. Evidence seems to suggest supplements may improve symptoms of inattention specifically, and not symptoms of ADHD more generally. A double-blind, placebo-controlled 16-week study giving boys aged 8 to 14 years fish oil (in a margarine spread containing 650 mg of EPA and 650 mg of DHA daily) found it to modestly improve parent-rated attention in boys with ADHD and in typically developing boys. Most of the boys with ADHD were also taking prescription medication. No effect, however, was seen in brain activity or on performance of cognitive control tasks (Bos, Neuropsychopharm 2015).

In contrast, an improvement in executive functioning was found in a study among 95 girls and boys (average age 11) with mood disorders (depression, bipolar disorder or unspecified) who took two capsules of fish oil providing a daily total of 700 mg EPA, 100 mg DHA and 134 mg other omega-3 fatty acids (OmegaBrite -- who provided the capsules) in addition to twice-weekly therapy sessions for three months. Significant improvements in parent-reported executive functioning (working memory and cognitive skills such as attention, planning, organizing, switching between tasks) were found in comparison to those who had the same therapy but took a placebo. The same dose of fish oil also significantly improved parent-reported executive functioning compared to placebo in children who did not receive therapy sessions (Vesco, J Child Psychol Psychiatry 2017). It is difficult to say, however, to what extent the improvements may have been due to improvements in depressive symptoms, which also occurred (Fristad, J Child Adolesc Psychopharmacol 2015; Fristad, J Clin Child Adolesc Psychol 2016).

A 12-week, placebo-controlled study among 92 children (6 to 18 years old) with ADHD found that high-dose EPA (1,200 mg daily) improved "focused attention," particularly among those who started with low EPA levels. However, on measures of "impulsivity," the EPA-treated group improved less than those given placebo, and those who started with high EPA levels also showed less improvement on other ADHD and emotional symptoms than the placebo group. The researchers supported the recommendation of a panel of ADHD experts (Banaschewski, Nutr Health 2018) that patients who prefer omega-3 supplements over stimulants should take at least 750 mg daily of a combination of DHA and EPA for at least 12 weeks, but not if a patient is already getting these omega-3s from their diet (Chang, Translational Psych 2019).

A study in China among 95 children (ages 7 to 12) found that 800 mg of algal oil (providing a total of 300 mg of DHA and only about 2 mg of EPA) taken after breakfast daily for six months did not improve executive function (i.e., attention, abstract thinking, working memory) compared to placebo, although both the algal oil placebo groups had improvements at six months compared to the beginning of the study. However, it was not noted whether any of the children had been diagnosed with ADHD or other learning disorders (Yang, Eur J Nutr 2020).

Reading Skills and Other Cognitive Abilities in Children
A double-blind, placebo-controlled study in boys and girls (ages 9 and 10) in Sweden found that a dose of 558 mg EPA, 174 mg DHA and 60 mg gamma-linolenic acid (GLA -- an omega-6 fatty acid) taken daily for three months modestly improved reading ability, including the ability to read and pronounce unfamiliar words and the ability to read a series of letters quickly, as well as reading comprehension, compared to placebo. Although none of the children had a reading disability or ADHD, the researchers noted that the greatest improvements were found in children who had attention problems (as reported by parents) (Johnson, J Child Psychol Psychiatry 2016).

Consumption of oily fish itself has shown benefit in improving certain measures of cognitive function in children according to a study among 197 healthy boys and girls (8 to 9 years of age) in Denmark. The study found that those who consumed approximately 11 oz. of fish per week (salmon, mackerel or trout) for three months (which increased average intake of EPA + DHA from about 135 mg to 913 mg per day) had modest improvements in tests of attention and cognitive flexibility (i.e. faster reaction times with fewer errors) than those who consumed an equivalent amount of poultry. Children who consumed fish also tended to have higher overall cognitive performance, although this did not reach statistical significance (Teisen, Am J Clin Nutr 2020).

During Pregnancy: Effects on Children
DHA is important for normal development and functioning of the brain and retina in the fetus and in infants. The benefits of fish oil supplementation during pregnancy with regard to brain function have not been established, although consuming a moderate amount of fish may be beneficial, and supplementation may reduce the risk of colds in infants and allergy and asthma in children. There is also some evidence that, in women with low omega-3 levels or intakes, DHA supplementation may reduce the risk of premature birth. In the U.S., there is no Dietary Recommended Intake (DRI) for DHA during pregnancy, but the FAO/WHO recommends a minimum intake of 200 to 300 mg of DHA per day and up to 1,000 mg during pregnancy and breastfeeding.

In an Australian study, pregnant women were given 800 mg of DHA and 100 mg of EPA daily (from 1,500 mg of fish oil in capsules) until birth. Compared to women given placebo (vegetable oil capsules), there was no statistically significant increase in cognitive or language development in offspring during early childhood (Makrides, JAMA 2010), nor when the children were evaluated again at 4 years of age (Makrides, JAMA 2014), nor when the children were tested for IQ at age 7 -- at which age they were reported to have slightly more behavioral and executive functioning problems than children in the placebo group (Gould, JAMA 2017). Similarly, a study in Spain evaluating the long-term effects of supplementing pregnant women with fish oil containing 500 mg of DHA and 150 mg of EPA from 20 weeks of gestation until delivery found no significant improvement in memory, attention, motor skills, language, or other measures of cognitive function in the children when evaluated at 9 years of age compared to children of mothers not given no fish oil (Azaryah, Nutrients 2020).

The Australian study described above did, however, find that maternal supplementation with fish oil significantly decreased very premature births (1.09% in the treated group vs. 2.25% in the placebo group) as well as the risk of low birth weight infants and need for admission to neonatal intensive care units. There were also fewer fetal/infant deaths among those taking fish oil, although not by a statistically significant margin. At the same time, more of the treated women were induced or had cesarean sections because they were post-term. Babies born to treated women in the study were nearly 40% less likely to have egg allergies in their first year of life in comparison to babies of untreated women. They were also less likely to have eczema, although this association did not hold after the results were adjusted for factors such as maternal history of allergies (Palmer, BMJ 2012). A related editorial recommended that pregnant women should get 200 mg of DHA per day either from a supplement or low-mercury fish and that the benefit of higher intakes remains unclear (Oken, JAMA 2010).

Similar to the results of the Australian study, a placebo-controlled study in Kansas in which expectant mothers were given 600 mg of DHA daily from 14.5 weeks of gestation until delivery found that high-dose DHA did not provide cognitive benefits to offspring, although it did reduce the risk of preterm birth (Colombo, Am J Clin Nutr 2019). Another placebo-controlled study in Australia did not find a reduction in preterm births among mothers given fish oil (providing a total of 800 mg of DHA and 100 EPA daily) within the first 20 weeks of pregnancy. There was also a 30% increase in babies who were very large for their gestational age, although this did not lead to an increase in interventions during delivery. However, participants began the study with higher blood levels of DHA than in studies that have found a reduction in the risk of preterm birth (and levels were approximately 20% higher than in the study above), which the researchers suggested may have contributed to the lack of benefit (Makrides, NEJM 2019).

A study among 1,032 pregnant women in the U.S. who took either a low (200 mg) or high (1,000 mg) daily dose of DHA (from algal oil -- Life's DHA-S oil, DSM Nutritional Products LLC) starting at 12 to 20 weeks gestation also suggests that supplementation with DHA may reduce the risk of early preterm birth (< 34 weeks gestation) in women with low levels of DHA. Among the women who began the study with low blood levels of DHA (< 6% RBC phospholipid DHA), those who took the high dose of DHA had half the rate of early preterm birth compared to those who received the lower dose (2% vs. 4.1%, respectively). Interestingly, women who began the study with high DHA levels had the lowest rate of early preterm birth (just 1.2%), regardless of whether they took low or high-dose DHA. All of the women who took the higher dose had longer gestation, fewer spontaneous labors, and their infants, greater birth weight and length, and fewer neonatal admissions to an intensive care unit, compared to those that took the lower dose — suggesting some benefits even in women without low levels of DHA, although women who took the higher dose were also more likely than those in the low-dose group to develop preeclampsia or gestational diabetes -- it is possible that prolongation of pregnancy allowed for development and diagnosis of these two conditions (Carlson, EClinicalMedicine 2021).

A major study in Denmark found that fish oil supplementation during pregnancy decreased the occurrence of persistent wheeze and asthma in offspring. Starting at 24 weeks of pregnancy, women took 4 capsules daily, each containing 1 gram of concentrated fish oil providing 330 mg of EPA and 220 mg of DHA in the triglyceride form. By age 5, wheeze/asthma had developed in 23.7% of children whose mothers received a placebo (olive oil), compared to only 16.9% of those whose mothers received the fish oil supplement. Fish oil was particularly important for children of women who started with lower blood levels of fish oil (one-third of the women) -- 35.1% in the placebo group developed asthma/wheeze compared to 17.5% in the supplemented group. Women in the U.S. tend to consume only half the amount of omega-3 fatty acids from their diets as those in Denmark, suggesting even greater potential benefit in the U.S. population (Bisgaard, NEJM 2016).

An analysis that weighed the potential cognitive benefits with the risks (from exposure to mercury) of consuming fish during pregnancy suggested that consuming two seafood meals (8 to 12 oz) per week during pregnancy could increase a child's IQ an additional 3.3 IQ points by age 9. Consuming this recommended amount as tuna provided increases between 2.8 and 3.1 IQ points, while salmon (which generally has a higher concentration of EPA and DHA) provides 3.2 IQ points; however, as noted by the researchers, the benefit may be due, in part, to nutrients from fish other than EPA and DHA, such as vitamin D, selenium, and amino acids. No adverse cognitive effects from mercury were expected from consuming this amount of fish per week, and depending on the type of fish, you would have to consume many times this amount before getting the minimum amount of mercury known to cause adverse cognitive effects (for example, 120 light tuna sandwiches per week) (McGuire, Nutr J 2016).

Infants born to women in Mexico given 400 mg DHA daily (from algal oil from Martek Biosciences) during pregnancy (starting at about 20 weeks) had a lower occurrence of colds during the first three month of life than those whose mothers received placebo treatment (37.6% vs. 44.6%, respectively) (Imhoff-Kunsch, Pediatrics 2011). However, median daily intake of DHA among pregnant women in Mexico is much lower than in the U.S. (80 mg vs. 100 to 200 mg, respectively), so the findings may not apply to groups already consuming higher amounts of DHA.

During Early Childhood:
A large study in which 1-year-olds in Ohio who were born preterm and had been weaned off breast milk and formula were given DHA (200 mg) and arachidonic acid (200 mg) daily for 6 months showed no improvement in cognitive development and early measures of executive function versus placebo, and possible negative effects on language development (Keim, JAMA Ped 2018). (Arachidonic acid (AA) is an omega-6 fatty acid believed to be important for infant growth and brain development. It is present in human milk and is commonly added to infant formula along with DHA (Hadley, Nutrients 2016).) The lack of effect on cognitive development is generally consistent with previous studies on infants and pre-term neonates, calling into question the benefit of DHA and AA supplementation in these groups.

Alzheimer's Disease:
Population studies suggest that consumption of DHA is associated with reduced incidence of Alzheimer disease and animal studies demonstrate that DHA intake reduces Alzheimer-like brain disease. However, a study showed that supplementation with DHA from algae did not slow cognitive and functional decline in individuals with mild to moderate Alzheimer disease (Quinn, JAMA 2010). There was also no apparent reduction in the decline in brain volume. In the study, patients received 2 grams of DHA from algal oil daily or placebo for 18 months. All of the patients had previously consumed less than 200 mg of DHA per day and had not taken supplements with DHA or EPA. Among those given DHA in the study, plasma levels of DHA tripled and the amount of DHA in cerebrospinal fluid increased by 38%, with no significant change in those taking placebo. It should be noted that the study did not assess whether DHA could play a preventative role in Alzheimer's disease, nor did it assess the effect of DHA in conjunction with EPA.

A placebo-controlled, one-year pilot study of 34 adults with mild to moderate impairment from Alzheimer's disease found that alpha-lipoic acid and fish oil slowed the decline in subjects' cognitive functioning. The combination also slowed the decline in subjects' abilities to perform daily activities, as did fish oil alone, but not alpha-lipoic acid alone. The participants normally ate fish no more than once per week and most continued to take Alzheimer's medications. A capsule of alpha-lipoic acid (600 mg) was taken each morning along with two fish oil capsules (each containing 1 gram of fish oil, providing 325 mg EPA and 225 mg DHA in the triglyceride form). Another fish oil capsule was taken with lunch (Shinto, J Alzheimers Dis 2014). Although earlier studies, such as that above, have not shown a benefit with omega-3 fatty acids in Alzheimer's disease, this study differed in that the fish oil had a high ratio of EPA to DHA.

A small study involving daily intake of a drink (Smartfish, Norway) providing 1,000 mg of EPA and 1,000 mg of DHA along with a modest amount of vitamin D (400 IU) and an undisclosed amount of antioxidants (pomegranate, chokeberry and resveratrol) found that the drink -- consumed daily for 4 to 17 months -- had no effect on cognition in people with Alzheimer's disease, nor in people with mild cognitive impairment. The study also evaluated the drink's effect on the ability of immune system cells in the subjects to remove amyloid beta — a neurotoxic molecule associated with Alzheimer's disease. No improvement in this immune function was found in Alzheimer's patients, although this did improve in people with mild cognitive impairment and normal cognitive function (Fiala, FASEB J 2015).

A study in Sweden among people with mild to moderate Alzheimer's disease found that daily supplementation with 1,700 mg of DHA and 600 mg of EPA for six months benefitted only those with adequate B vitamin status (determined by blood levels of homocysteine). In comparison to those with higher homocysteine levels, people with levels below 11.7 mmol/L experienced a 7.1% improvement in cognitive performance and a 22.3% reduction on a rating scale of dementia. This was consistent with an earlier study by the same researchers that showed B vitamins were most helpful in reducing brain shrinkage in Alzheimer's patients who had higher blood levels of EPA and DHA. The researchers explained that the two types of nutrients work together: B vitamins are necessary to form phosphatidylcholine which is necessary to carry DHA and EPA over the blood-brain barrier (Jerneren, J Alz Dis 2019).

Age-related Cognitive Decline:
Many studies have explored the use of DHA-rich fish oil for people with age-related cognitive decline (ARCD). Unlike Alzheimer's disease, ARCD is not considered a disease and is a more gradual and, perhaps, normal consequence of aging. The benefit has generally been modest at best and may depend on stage of cognitive decline, age of the person, and whether or not they are already consuming fish in their diet, as described below.

A six-month study of people over age 65 with mild cognitive impairment showed that those receiving daily fish oil containing a large amount of DHA (1,550 mg) with EPA (400 mg) improved scores on verbal fluency (although not on any other memory or cognition test) compared to those in a control group receiving safflower oil (containing the omega-6 fatty acid, linoleic acid). An EPA/DHA combination (1,670 mg EPA with 160 mg DHA) did not affect any aspect of cognition or memory. However, both the EPA/DHA combination and, to a slightly greater extent, the DHA/EPA combination reduced depressive symptoms in these mildly cognitively impaired individuals (Sinn, Br J Nutr 2011). The researchers note that depression is a potential risk factor for progression to dementia, so the reduction of depressive symptoms may reduce the risk of dementia. In another study (Yurko-Mauro, Alzheimer's & Dementia 2010), participants with ARCD were given 900 mg per day of DHA from algal oil or placebo for 24 weeks. Those taking DHA showed significant improvements in verbal recognition memory, but no improvement in working memory or on executive function tests. Plasma DHA levels doubled in the group receiving the supplementation.

A multi-year study of several hundred older individuals (approximately 70 to 80 years of age) found that cognitive function and brain volume (size) were better preserved among those who reported using fish oil supplements than those who did not (the types and dosage of fish oil used were not identified). The effect, however, was only seen among those who started with normal cognitive function, not those who already had mild cognitive impairment or Alzheimer's disease. In addition, the benefit was only found among people who did not have a specific gene (APOE e4) associated with increased risk of Alzheimer's disease. The researchers note that these apparent effects are consistent with other research. Similarly, other studies have shown a positive association between consumption of fatty fish and better cognitive health and indicate that middle age may be a particularly significant period for the potential role of omega-3 fatty acids in better cognitive aging. (Daiello, Alzheimer's & Dementia 2015). Analyses of two studies that showed reduced cognitive decline and reduced brain shrinkage with a B vitamin combination concluded that the benefits were only found among people who began the studies with blood plasma levels of omega-3 fatty acids in the upper range of normal (see B Vitamin Review).

A six-month study among 33 individuals aged 55 years and older (average age 69) who were cognitively unimpaired but with a first-degree family history of dementia showed that supplementing with 2,152 mg of DHA (in triglyceride form) and virtually no EPA daily led to a 28% increase in DHA in the cerebral spinal fluid and a 43% increase in EPA (likely due to conversion of DHA) compared to the effects of a placebo (corn/soy oil). There were, however, no significant differences between the groups in terms of change in brain volumes and cognitive scores. The findings suggest that lower doses of DHA might be insufficient to significantly affect DHA levels in the brain. The study also showed that the DHA and EPA levels in the cerebral spinal fluid tended to increase more among participants who did not carry the APOE4 gene than in carriers of the gene. All participants in the study were simultaneously supplemented with B vitamins (Arellanes, EBioMedicine 2020).

Neither daily fish oil (650 mg of EPA and 350 mg of DHA) nor lutein and zeaxanthin (10 mg and 2 mg, respectively) were found to reduce cognitive decline in a large, well-controlled, five-year study of older individuals in the U.S. (average age of 73) who were part of a larger study of supplements to slow age-related macular degeneration, an eye disease (see the AREDS2 study). Yearly decline in cognitive function was essentially the same for those taking these supplements as for those taking placebo (Chew, JAMA 2015). However, the study population was described as "well-nourished" and may have already been regularly consuming fish.

A placebo-controlled study of healthy older individuals in China with mild cognitive impairment found that taking 2 grams of DHA from algal oil daily for one year improved aspects of short- and long-term memory, although not other measures of cognition (e.g., arithmetic, vocabulary). MRI scans of those given algal oil (from Martek Biosciences, whose parent company, DSM, funded the study) showed a 4% increase in the volume of the hippocampus (a key area for memory formation), while those given a similar amount of corn oil did not have this improvement, nor improvements in cognitive function (Zhang, J Alz Disease 2016). Another study among older men and women (average age 71) in China with mild cognitive impairment found that 480 mg DHA and 720 mg EPA per day from fish oil slightly improved overall measures of cognitive function, perceptual speed and working memory, but not mental arithmetic efficiency or recognition memory, compared to placebo (olive oil) (Bo, Nutrients 2017). Blood levels of DHA and EPA in participants were somewhat low at the beginning of the study, which may help explain why supplementation was helpful.

A large study in France among older adults (average age 75) with self-reported cognitive difficulties found that supplementing with 800 mg of DHA and 225 mg of EPA from fish oil daily did not reduce cognitive decline compared to placebo. There was also no benefit from a lifestyle intervention (physical activity, cognitive training, and nutritional advice) by itself or in combination with omega-3 supplementation (Andrieu, Lancet Neurol 2017). Similarly, an 18-month study in Australia among older adults (average age 73) found that daily supplementation with 1,720 mg of DHA and 600 mg of EPA did not help maintain or improve cognitive performance relative to results with placebo (an olive oil low in polyphenols). However, those in the study were consuming fish twice per week on average (Danthiir, Am J Clin Nutr 2018).

An open-label study in Boston among cognitively healthy people (average age 64) with coronary artery disease showed that those given high-dose, high-concentration fish oil (1,860 mg of EPA and 1,500 mg DHA in the ethyl ester form, from four softgels of Lovaza) for 30 months experienced higher verbal fluency, language, memory and visual-motor coordination scores compared to a control group that did not supplement with fish oil. The improvements in cognitive function for the fish oil group were observed beginning at 12 months and persisted through 30 months (Malik, Am J Clin Nutr 2021). The study did not discuss the amount of fish oil participants were consuming from their normal diet. [An initial report of these results suggested that those who were younger, nondiabetic, or who achieved an omega-3 fatty index of at least 4% had the greatest benefit (Vemuri, Circulation 2019 — abstract), but this deeper analysis of the data showed no differences based on these criteria.] (This study also showed cardiovascular benefits, as reported by Alfaddagh.)

In summary, the omega-3 fatty acid DHA (900 to 2,000 mg daily), such as from fish or algal oil, may slow some aspects of age-related cognitive decline in people without advanced dementia, but the benefit seems limited to use during middle age and/or among those who are not getting significant omega-3 fatty acids in their diet and who are not diabetic.

Not surprisingly, consumption of fish itself has been associated with a lower risk of cognitive impairment and slower decline of cognitive function. Two related studies involving a total of 7,756 older adults found that closer adherence to a Mediterranean diet (fish, nuts, olive oil, whole grains, legumes, vegetables, and fruits) over five years was associated with a 40% to 50% lower risk of developing cognitive impairment, but the food that appeared to be driving the association, and the only food associated with slowing cognitive decline, was fish. Significant benefit was seen starting with only around one serving per week and the benefit increased somewhat as fish consumption increased to about 2 to 4 servings per week (Keenan, Alz Dem 2020).

Memory Enhancement in Healthy Individuals:
Some, but not all, studies suggested limited improvements in cognition and/or memory with omega-3 supplementation, although benefits appear to be limited to people starting with low blood levels of DHA or little fish intake.

A placebo-controlled study in 65 healthy adults ages 50 to 75 years, found that taking fish oil for 6 months resulted, on average, in a 26% improvement in executive functioning (e.g., verbal fluency, visual tasks, reading ability). There was no overall improvement in memory, although there was an improvement in memory consolidation -- the recall of words after a 30-minute delay. Those who took the fish oil also had significant gains in the structure and volume of tissue in several areas of the brain, improvements in the lining of the carotid artery, and a 3.4% reduction in diastolic blood pressure. The participants took four fish oil capsules daily, each containing 1,000 mg of fish oil (300 mg EPA and 220 mg DHA) which included 15 mg of vitamin E as preservative, and continued eating their normal diet, with most consuming fish once per week (Witte, Cereb Cortex 2013). A placebo-controlled study that looked at blood flow to the brain in older women and men (ages 50 to 80) in Australia who were sedentary and obese and were not large consumers of fish or fish oil found that supplementation with 1,000 mg of DHA and 200 mg EPA (triglyceride forms) taken with breakfast and, again, with dinner reduced stiffness of the cerebral arteries, although blood flow to the brain was found to increase only among men. The fish oil reduced heart rate and triglycerides and increased HDL cholesterol. The addition of curcumin provided no additional benefit (Kuszewski, Nutr, Met Cardio Dis 2020).

Similarly, a study among 271 healthy adults ages 30 to 54 years with generally low intakes of omega-3 fatty acids from their diet (< 300 mg per day) found that taking two 1,000-mg fish oil capsules (each providing 500 mg EPA + 200 mg DHA) daily for four months resulted in significant improvement, relative to placebo, in executive functioning but only among those who began the study with the lowest blood levels of DHA (< 2.45% of total fatty acids). Across the broader group there was no improvement in executive functioning, psychomotor speed, learning/episodic memory, or fluid intelligence (i.e. reasoning) (Leckie, Psychol Med 2019).

In a small study of healthy young adults, better working memory performance has been found to correlate with higher levels of DHA (as measured in red blood cell membranes), but not EPA (Narendran, PLoS One 2012). Working memory performance was tested by showing a series of letters and numbers and asking what appeared one, two, and three times prior. Those who had higher DHA levels performed better on the "3-back" question than those with lower levels. The subjects were then asked to take 2 grams of highly-concentrated fish oil (Lovaza, 930 mg EPA and 750 mg DHA) daily for six months and tested again: Scores improved on the "3-back" question and those who previously had the lowest DHA levels improved the most. Similarly, another 6-month study in healthy young adults with diets low in omega-3 fatty acids found those given a DHA-rich fish oil supplement daily (2,250 mg of fish oil providing 1,160 mg of DHA and 170 mg EPA) had improved memory performance compared to those who received placebo (Stonehouse, Am J Clin Nutr 2013). Specifically, women had greater improvements in episodic memory -- correctly remembering one more word or picture, while men experienced greater improvements in reaction times of working memory -- completing tasks 20% faster than men in the placebo group. The report notes that six-months was chosen as the study period as this is required for DHA levels in tissue to plateau.

A study in Holland among adolescents with lower educational performance and generally low starting blood levels of omega-3 fatty acids who were given krill oil capsules (providing 520 mg of EPA + 280 mg DHA daily) for one year did not find improvements in measures of cognition compared to placebo, or any association between blood levels of omega-3 fatty acids and cognitive performance. However, it is difficult to draw conclusions from this study because average blood levels of omega-3 fatty acids actually decreased in those taking krill oil, possibly due to very low compliance (van der Wurff Nutrients 2019). Baseline testing (before starting krill) of the students had shown a positive association between levels of EPA + DHA in their blood and performance on two cognitive measures: processing speed and impulsivity control, but no association with short-term memory or six other cognitive measures (van der Wurff, Nutrients 2016).

Strength and Muscle:
Omega-3 fatty acids can help maintain and build muscle tissue. Evidence from several studies suggests that fish oil can help maintain muscle mass and modestly improve muscular strength and/or endurance and enhance the effects of training.

A study among 20 recreationally active young women who had one leg experimentally immobilized with a knee brace for two weeks found that those who started taking daily high-dose fish oil four weeks before immobilization had less decline in muscle volume than those given sunflower oil (8% vs. 14% decline, respectively). In fact, two weeks after the brace was removed, muscle volume was back to normal for those who had taken fish oil but it remained reduced in the control group. Biopsies revealed that muscle synthesis was higher with the fish oil group throughout the study. Following immobilization, leg strength decreased more in the control group than in the fish oil group, but the difference was not statistically significant. The fish oil was taken as a liquid providing 2,970 mg of EPA and 2,030 mg of DHA daily (McGlory, FASEB J 2019).

A six-month, placebo-controlled study in healthy older men and women (60 to 85 years of age) found that high-dose, extremely concentrated fish oil increased muscle mass and function, while these declined in the control group receiving corn oil. The fish oil was Lovaza, taken as 2 pills with both breakfast and dinner, providing 1,860 mg of EPA and 1,500 mg of DHA daily (similar to amounts in about 3 servings of fatty fish). Compared to the control group, those getting the fish oil had about a 3.5% increase in muscle mass and a 6% increase in strength. The researchers noted that the therapy made up for 2 to 3 years of losses associated with normal aging and these changes were the same or greater than those which have been reported with testosterone, growth hormone, or DHEA, but less than what has been reported with exercise (Smith, AJCN 2015). Similarly, a study among healthy older adults (average age 70) who performed resistance exercise (twice per week) found that 3 grams of fish oil daily, providing a daily total of 2,100 mg of EPA and 600 mg of DHA (Barlean's) increased muscle strength by 34% in women. This was significantly greater than the 16% increase among women given placebo. In men, however, fish oil did not result in significant improvement compared to placebo. The researchers speculated that older women may have a greater capacity for improvement from resistance exercise than older men. Unlike the study discussed further above, there were no increases in muscle mass in either women or men (Da Boit, Am J Clin Nutr 2016).

A small study in Brazil looked at the potential benefit of fish oil on strength training in older individuals, based on the fact that omega-3's play a role in the plasma membrane and cell function of muscles (Rodacki, Am J Clin Nutr 2012). Forty-five mostly sedentary women in their mid-60s were given two doses a day of a gram of fish oil containing 180 mg of EPA and 120 mg of DHA. After twelve weeks of supervised lower-body resistance-training (three times per week), the strength of those taking the fish oil had improved more than those who did not supplement. Functional capacity (e.g., the speed of rising from a chair) also increased more among those who took fish oil. There was no improvement in the strength of women who took fish oil without strength training, and taking fish oil for two months before training started did not confer added benefit.

A small study among male and female European competitive soccer players (average age 22) found that a high daily dose of fish oil (100 mg/kg of bodyweight; average dose 7 grams of fish oil providing 4,900 mg of EPA and 1,400 mg DHA daily) taken for one month modestly improved exercise endurance compared to placebo. After one month, those who took the fish oil were able to run an average of 203 meters further than before supplementation began, while those who took the placebo ran an average of 63 meters further; however, there were no improvements in running speed, or muscle strength or power (Gravina, Int J Sport Nutr Exerc Metab 2017).

A study among young resistance-trained men and women found that taking 3 grams of krill oil (providing 240 mg DHA, 393 mg EPA, and 0.54 mg astaxanthin) daily for two months while participating in regular resistance exercise did not increase strength, lean body mass, nor cognition, significantly more than an equivalent amount of olive oil given as a placebo (Georges, J Nutr Metab 2018).

Muscle Pain and Inflammation After Exercise (Omega XL):
A small study found that daily supplementation with a combination of green-lipped mussel oil, olive oil and vitamin E (Omega XL/PCSO-524, Pharmalink International) significantly reduced muscle damage, pain and inflammation after exercise in young men (average age 22) (Mickleborough, J Int Soc Sports Nutr 2015). In the study, the men took eight Omega XL capsules per day (providing a total daily dose of 800 mg olive oil, 400 mg green lipped mussel oil extract (58 mg EPA + 44 mg DHA) and 1.8 mg vitamin E) or 8 placebo capsules (containing 1,200 mg olive oil) daily for one month. On the 26th day of supplementation, the men performed a downhill running exercise designed to induce muscle damage. Those who took the green-lipped mussel oil combination had significantly less delayed-onset muscle soreness (DOMS) on the third and fourth day after exercise, as well as lower levels of certain blood markers for muscle damage and inflammation, compared to those who took a placebo. The study was funded by Pharmalink International. [Note: this product was tested by ConsumerLab.com in 2014 and 2016 and was neither "Approved" or "Not Approved" because the label did not claim to contain a specific amount of omega-3 fatty acids — it was found each time to contain only about 6 mg of EPA and 5 mg of DHA per softgel, very low amounts compared to other omega-3 fatty acid supplements, although consistent with the amounts per pill in the above study.] 

There is mixed evidence that Omega XL/PCSO-524 may also be helpful for other conditions, and many of the clinical studies on this product were not properly designed (i.e. not double-blinded, placebo-controlled, etc.). For example, one study found it significantly reduced pain and improved physical function in men and women with osteoarthritis of the knee and/or hip when compared to fish oil (Zawadzki, Mar Drugs 2013), but another study found no such benefit when compared to a placebo (Lau,Progress in Nutrition 2004). In addition, a study found Omega XL/PCSO-524 to reduce the occurrence of wheezing in adults with asthma (Emelyanov, Eur Respir J 2002), while a study in children with asthma found no benefit compared to placebo (Lello, Inter J of Asthma, Allergy and Immunol 2012). Any promotion of the product for heart health appears to be based on the fact that it contains omega-3 fatty acids, not published clinical studies, although, as noted, it contains a scant amount of omega-3s. (See Cautions and Concerns for safety concerns about green-lipped mussel extract).

Acne:
A small study found that daily supplementation with either omega-3 fatty acids (EPA and DHA) or the omega-6 fatty acid GLA significantly reduced the number and severity of acne lesions in men and women ages 18 to 33 years old with mild to moderate acne (Jung Acta Derm Venereol 2014). Participants received two capsules daily containing either omega-3 fatty acids (providing a total of 1,000 mg EPA and 1,000 mg DHA) or GLA (providing a total of 400 mg GLA from 2,000 mg borage oil) for 10 weeks. A third group, serving as the control, did not receive supplementation or any other treatment. At the end of the study, both treatment groups experienced a significant reduction in the number of inflammatory acne lesions (42.6% and 32.7%, respectively) and non-inflammatory acne lesions (19.6% and 15.8%, respectively). There was also a significant reduction in the severity of acne lesions in both groups (29% and 22%, respectively). No significant changes were seen in the control group.

Periodontitis (Inflammation Around Teeth):
A small, controlled, 3-month study found that giving 2,000 mg per day of DHA (from four capsules of algal oil which was 53.6% DHA) along with low-dose aspirin (81 mg per day) improved outcomes in people with periodontitis (inflammation around teeth causing pocketing) in comparison to aspirin plus placebo (soy/corn oil). Those receiving the DHA had greater reductions in local inflammation and pocketing around teeth (Naqvi, J Dent Res 2014). The researchers speculate that, in the presence of aspirin, DHA is converted to a compound used by certain white blood cells to produce other compounds (e.g. resolvins and protectins) which help resolve inflammation. Aspirin alone does not have this effect and it is not known whether DHA alone would have this effect. An earlier pilot study of EPA alone did not affect periodontitis, although positive results were seen with 2,000 mg per day of GLA (an omega-6 fatty acid) (Rosenstein, Prosta Leukot Essent Fatty Acids 2003).

Protection from Effects of Air Pollution:
A small study by scientists at the U.S. Environmental Protection Agency (EPA) in middle-aged people found that fish oil supplementation protected against adverse cardiac and lipid effects associated with air pollution exposure (Tong, Env Health Perp 2012). Participants in the study were given daily capsules of fish oil (3 grams, providing 1230 mg EPA and 822 mg DHA) or olive oil for four weeks and then exposed to air containing particles for two hours. This caused the group taking olive oil to experience undesirable changes in blood lipids (increased LDL and triglyceride levels), but this did not occur in the fish oil group. The fish oil group also experienced less negative effects on heart functioning than the olive oil group.

However, a second small study found that supplementation with olive oil provided protection against other vascular effects of air pollution that fish oil supplementation did not. In the study, middle-aged men and women who took 3 grams of olive oil daily for four weeks experienced significantly better endothelial function after being exposed to air conditioning particles for two hours compared to those who took 3 grams of fish oil or placebo (Tong AJRCCM 2014). This suggests that olive oil and fish oil may each offer different cardio-protective benefits when it comes to air pollution exposure.

Testosterone, Fertility and Semen Quality
Despite animals studies suggesting that consumption of omega-3 fatty acids increases testosterone levels in males (Zaima, Biochem Biophys Rep 2016; Sebokova, J Nutr 1990), studies in men have shown mixed results, although an association between fish oil use and improved semen and sperm levels was found in one analysis. A study in 26 men (average age 37) found that a high daily dose fish oil (5 grams of EPA + DHA) taken for one month did not increase free (biologically active) or total testosterone levels compared to placebo (Hughes, Atherosclerosis 1990). Similarly, a large, placebo-controlled study of older men (ages 60 to 80) with a history of heart attack (which increases the risk of testosterone deficiency), a modest daily dose of 400 mg of EPA + DHA did not increase total testosterone levels, nor the risk of testosterone deficiency, compared to placebo (Giltay, Int J Androl 2012). On the other hand, a placebo-controlled study in Australia among overweight and obese men and women (average age 51) found that 1 gram of fish oil (EPAX1050 -- 430 mg DHA + 60 mg EPA) taken twice daily with meals for three months significantly increased total testosterone levels in men (by 1.95 nmol/L compared to placebo, which is more than a 10% increase) but not in women. However, levels of free ("active") testosterone were not measured (Kylie, Prostaglandins Leukot Essent Fatty Acids 2020).

A study of 1,679 healthy young men in Denmark found that use of fish oil supplements (dosage not recorded) over the prior three months was associated with significantly better testicular function with regard to semen volume, sperm count, and testicular size, particularly if fish oil had been taken for 60 or more days in that period. There was no such association with the use of other supplements, such as multivitamins or vitamins C or D. The authors noted that these results are consistent with previous studies of men at fertility clinics and of healthy men given a significant amount (75 grams) of nuts to consume daily, possibly due to the fact both fish oil and nuts provide polyunsaturated fatty acids which are important constituents of sperm cell membranes. Conversely, saturated fat has been associated with lower sperm counts (Jensen, JAMA Net Open 2020).

Menopausal Symptoms:
A randomized, placebo-controlled study in Iran among 180 postmenopausal women (average age 53) found that fish oil supplementation once daily for three months reduced menopausal symptoms — including sweating, hot flashes, sleep problems, depressed mood and anxiety but not joint discomfort, bladder problems or vaginal dryness — better than placebo and similar to taking soybean extract. Fish oil was given as Omega-rex 1,000 mg softgels (providing a total of 180 mg of EPA and 120 mg of DHA daily), and soybean extract was given as Soygan 500 mg capsules (containing 500 mg of soybean powder and extract) daily (Purzand, Complement Ther Clin Pract 2020).

COVID-19
Fish oil does not appear to reduce the risk of hospitalization or death with COVID-19, but has possible benefits for inflammation, symptoms, and loss of smell.

A placebo-controlled trial among 2,052 patients with mild to moderate COVID in which high-dose, high-concentration prescription fish oil (Vascepa) or placebo was given daily (8 grams for 3 days followed by 4 grams for 25 days) found no statistically significant difference in the percentage of COVID-19-related hospitalizations with fish oil versus placebo (11.2% vs. 13.7%) or deaths (16% vs. 22%) at day 28, and those who received placebo had slightly shorter hospital stays (Dharam, J Am Coll Cardiol 2021).

A preliminary study among 91 COVID patients given the same type and dose of fish oil in the study above reported reductions in inflammation and flu-like symptoms compared to standard treatment alone; however, there was no placebo control. Over the 14 days of treatment, symptoms were reduced by 52% in the Vascepa-treated group compared 24% in patients who did not receive Vascepa. Those who received Vascepa also had a greater decrease in the inflammatory biomarker, C-reactive protein (CRP), compared to those who received standard treatment alone (25% vs. 5.6% decreases, respectively), after adjusting for age, sex, and cardiovascular risk (Kosmopoulos, iScience 2021).

Based on limited animal and human research suggesting that omega-3 fatty acids may be beneficial for loss of smell due to olfactory nerve damage, The British Rhinological Society advises that fish oil supplementation (2,000 mg of omega-3 fatty acids/day) may be beneficial when used in addition to standard treatment (olfactory training, oral steroids and steroid rinses) (Hopkins, Clin Otolaryngol 2020). Research has shown that animals deficient in omega-3 fatty acids may be more likely to have an impaired sense of smell (Greiner, Physiol Behav 2001). In older adults, higher intakes of fish have been associated lower risk of loss of smell (Gopinath, Br J Nutr 2015). In addition, a six-month study among 87 people who underwent endoscopic tumor removal surgery (which can cause olfactory nerve damage) found that that those that supplemented with fish oil (one capsule of Nature Made Ultra Omega-3 Fish Oil 1,400 mg twice daily providing a total of 2,000 mg of omega-3 fatty acids per day) in addition to standard treatment (twice daily nasal irrigation) were less likely to experience loss of smell than those who did standard treatment only (Yan, Neurosurgery 2020). The British Rhinological Society's guidelines did not find sufficient evidence to recommend vitamin A drops or alpha lipoic acid, which have also been suggested by some to be helpful for COVID-19 related loss of smell.

Other Diseases:
Other proposed uses of fish oils with some support include chronic fatigue syndrome, cystic fibrosis, and osteoporosis.

More research is needed to determine if fish oil supplementation is helpful for Raynaud's phenomenon (abnormal sensitivity of hands and feet to cold). In a small clinical trial, supplementation with 12 fish oil capsules daily (providing a total of 3, 960 mg EPA and 2,640 DHA daily) for six weeks modestly increased the time of onset of symptoms when exposed to cold (which correlated with increased systolic blood pressure in the fingers), compared to before supplementation, in people with primary Raynaud's phenomenon, but did not appear to be helpful in people with Raynaud's phenomenon due to other health conditions (DiGiamcomo, Am J Med 1989). On the other hand, another study found no association between total dietary fish oil consumption and the length or frequency of attacks in people with Reynaud's (Foley, FASB J 2016).

The balance of current evidence suggests that fish oil is not effective for psoriasis and enhancing immunity in people with HIV. Although some research has indicated that omega-3 fatty acid supplements might have anti-inflammatory effects that could benefit patients with multiple sclerosis (MS), a placebo-controlled study of 92 MS patients found no beneficial effect with daily fish oil (1,350 mg EPA and 850 mg DHA) for 2 years whether taken alone (for 6 months) or in combination with interferon (for 18 months) (Torkildsen, Arch Neurol 2012).

Pet Use:
Fish oil supplements are commonly given to pets to help maintain their coats and skin. [Reviews of other pet supplements by ConsumerLab.com include ALA and GLA, Joint Supplements and Multivitamins/Multiminerals.]

For information on dosages see What to Consider When Using.

Quality Concerns and Tests Performed:

Because omega-3 fatty acids are obtained from natural sources, levels of fatty acids in supplements can vary, depending on the source and method of processing.

Contamination has also been a concern because fish can accumulate toxins such as mercury, dioxins, and polychlorinated biphenyls (PCBs). Mercury can damage the nervous system -- particularly in a fetus. Dioxins and PCBs may be carcinogenic at low levels of exposure over time and may have other deleterious effects. However, while these contaminants remain of concern in fish meat, they have generally not been found to occur at dangerous levels in fish oil likely due to the purification processes used in preparing fish oil as well as the fact that contaminants like mercury bind to protein (meat) and not to oil.

The freshness of the oil is also an important consideration because rancid fish oils can have an extremely unpleasant odor and taste, and oxidized fish oil may be less safe and effective. A 7-week study in Norway, for example, found that high-quality (non-oxidized) fish oil taken daily by healthy adults resulted in a 6% decrease in LDL ("bad") cholesterol, while oxidized fish oil resulted in a 19% increase in LDL. Total cholesterol also decreased with high-quality fish oil compared to oxidized fish oil. Each fish oil contained the same amount of omega-3 fatty acids (700 mg EPA and 900 mg DHA). The researchers speculated that oxidized fish oil might enhance the solubility of cholesterol in the gut and increase its absorption, thus raising cholesterol levels (Rundblad, Br J Nutr 2017). Similarly, an earlier study found that highly oxidized (spoiled) omega-3 fatty acids from capsules had a negative effect on cholesterol levels in contrast to less oxidized omega-3 fatty acids which reduced triglyceride and cholesterol levels (Garcia-Hernandez, Int J Food Sci Nutr 2013).

While you can sometimes tell that a fish oil is rancid when you take it directly as a liquid, this can be masked by added flavors and not readily detected if you use a softgel and other encapsulated product. There may be safety considerations with oxidized fish oils due to a variety of compounds produced, some of which are odorless, such as peroxides. A study commissioned by the government of Norway (where fish oil supplement use is extremely high) concluded there would be some health concern related to the regular consumption of oxidized fish/marine oils, particularly in regards to the gastrointestinal tract, but there is not enough data to determine the risk (The Norwegian Scientific Committee for Food Safety, 2011). The study explained that the amount of spoilage and contamination in a supplement depends on the raw materials and processes of extraction, refining, concentration, encapsulation, storage and transportation. However, it saw no significant risk of contamination by microorganisms, proteins, lysophospholipids, cholesterol, and trans-fats. (ConsumerLab.com's tests of fish oil also indicate only insignificant amounts (less than 1%) of trans-fats, meaning that a capsule with 1,000 mg of fish oil contains less than 10 mg, or 0.01 grams, of trans-fat.)

Some studies of the freshness of supplements have suggested that a large percentage may be oxidized. For example, a study in Canada of mostly fish oil supplements (Jackowski, J Nutr Sci 2015) found that 50% exceeded voluntary oxidation limits. However, this study did not necessarily exclude products containing flavors that can interfere with testing, and this may have led to misleading findings and the conclusion that children's products (80% of which included flavorings) were more likely to be oxidized. The study also concluded that encapsulated, unflavored fish oil appears to be the safest and most readily testable type of product. It should be noted, however, that several of the researchers were employees of Pivotal Therapeutics, Inc., which exclusively sells encapsulated, unflavored fish oil.

A private research group in Boston reported that three "top-selling" fish oil dietary supplements "exceeded maximum international industry standards" with regard to oxidization, but an extremely concentrated prescription fish oil did not (product identities were not disclosed). It also reported that each supplement contained "significant levels of saturated fat in addition to desirable omega-3 fatty acids." The report, however, is somewhat misleading in that 1) the oxidation values for the supplements were inflated by the researchers to "normalize" them to one gram of omega-3 fatty acids, rather than to one gram of fish oil -- which is the true industry standard, and 2) fish oil naturally contains saturated fats as well as unsaturated fats, so finding some saturated fats is expected and is not surprising. Amarin Pharma, the maker of a prescription fish oil (VASCEPA) funded the writing of the report (Mason, Biochem and Biophy Res Comm 2016).

A study of 33 fish and marine oil supplements purchased on the internet and in retail stores in Norway found peroxide levels (one measure of oxidation) to vary almost 10-fold, from 1.04 to 10.83 meq/kg, but the average level among products was 3.61 meq/kg, which is well below the GOED limit of 5 meq/kg which ConsumerLab.com applies in its reviews (Halvorsen, Food Nutr Res 2011). GOED (the Global Organization for EPA and DHA — a fish oil trade group) funded its own study of popular U.S. fish oil supplements purchased in 2016 and found that "nearly half of 17 tested products for which all quality parameters could be tested did not meet at least one of the oxidative quality criteria or their label claim for EPA + DHA." The GOED report includes product-specific findings (Bannenberg, J Food Comp Analys 2020 -- Table 1, pg. 35). Interestingly, two of the products that passed testing were also Approved in Reviews by ConsumerLab (Spring Valley Fish Oil 1200 mg [2018] and Natural Factors Rx Omega-3 400 EPA/200 DHA [2016]), while none that failed GOED's tests had been Approved by CL.

Another study funded by GOED found that the susceptibility of fish oil to oxidation depends on the specific fish oil evaluated and the oxidation conditions to which the fish oil is exposed. Incorporating antioxidants such as mixed tocopherols into fish oil tends to delay oxidation. For instance, refined anchovy oil stabilized with added mixed tocopherols resisted oxidation following exposure to light and oxygen (i.e., photo-oxidation), while hoki liver oil containing only some natural alpha-tocopherol (but no added mixed tocopherols) became rancid rapidly. Refined anchovy oil also resisted degradation at higher temperatures (i.e., thermal degradation) better than hoki liver oil, although both fish oils lost antioxidant protection at longer exposure times. The researchers noted that the oxidation conditions used in the study were severe and that commercially available fish oil products are unlikely to be exposed to such conditions, although they did note that some of the oxidation byproducts were present in both fish oils even at baseline, indicating the byproducts may be formed at low levels during processing or storage (Phung, Foods 2020).

ConsumerLab.com's tests for spoilage were conducted on newly opened products, maintained out of heat and moisture. However, be aware that spoilage may occur after products are opened and exposed to air and/or excessive heat (see Keep It Fresh for storage tips). Lemon and other citrus flavorings, which are common in marine oil supplements, as well as vanillin, can interfere with spoilage testing, giving a falsely high reading. In addition, deeply colored oils, such as krill, cannot be evaluated in this test. Consequently, ConsumerLab.com was not able to determine spoilage in such products, as indicated with "N/A" (not applicable) in the "Freshness" column of the results table below). To be sure a product was not spoiled and passed oxidation tests, look for a "pass" in for "Freshness" in the 3rd column of the Results table.

Capsules that are enteric-coated and are expected to release the oil after the stomach to theoretically reduce fishy aftertaste or burp. If they release too soon they lose that potential benefit. If they release too late, the oil may not get absorbed. ConsumerLab.com tested enteric-coated fish oil products according to the specifications set forth by the United States Pharmacopeia (USP).

Neither the FDA nor any other federal or state agency routinely tests fish or marine oil supplements for quality prior to sale. ConsumerLab.com, as part of its mission to independently evaluate products that affect health, wellness, and nutrition, purchased many dietary supplements sold in the U.S. claiming to contain EPA and/or DHA and tested them for their levels of omega-3 fatty acids (EPA, DHA, DPA and, if listed, ALA), lead, cadmium, arsenic, mercury, and signs of spoilage (unless the product had issues preventing accurate testing for spoilage, as noted above). Enteric-coated capsules were tested to see if they properly released their ingredients. Krill oils were additionally tested for amounts of phospholipids and astaxanthin. Among the products purchased and tested, the majority was for use by people and some were for pets. Most of the supplements were softgel capsules or liquids.

For more information about the testing, see How Products Were Evaluated.

What CL Found:

Among the 17 products that ConsumerLab.com selected for review (including two products for pets), 14 were "Approved" for quality — meaning that they met labeling requirements and tests for freshness and purity (i.e., lack of contamination by heavy metals), containing their claimed amounts omega-3 fatty acids, and, if enteric coated, disintegrating properly. An additional 14 products that were tested through CL's Quality Certification Program passed testing and were also Approved. 

Problems Discovered

· Viva Naturals Antarctic Krill Oil contained only 63.3% of its listed 1,600 mcg (1.6 mg) of astaxanthin. It did, however, contain its listed amounts of omega-3 fatty acids. Interestingly, the product has an IKOS seal, implying that it was tested and certified by Nutrasource (a consulting company in Canada that helps "health product companies meet government requirements and support their product claims."). However, the Nutrasource website does not list the lot we tested (2004024 Exp 04/2022) as certified, so it is unclear why it bears an IKOS seal. In fact, a different lot that is listed on the site with the same expiration date is reported as containing 4.6 mcg of astaxanthin, nearly three times amount claimed and four times what we found, which further suggests a quality control issue. We also found a relatively high amount of arsenic in Viva Naturals, although, fortunately, extremely little was in the more toxic "inorganic" arsenic form.

· Freshfield Vegan Omega-3 DHA + DPA claimed to contain 500 mg of total omega-3 fatty acids per vegetarian gelcap, but we found less than half — just 233.9 mg per vegetarian gelcap. It did, however, contain its listed amounts of DHA and DPA.

· Doctors Foster + Smith Premium Plus Omega-3 — For Dogs contained only 51% of its listed EPA and 44.2% of its listed DHA.

Although ConsumerLab.com did not find any products to be spoiled, be aware that, due to chemical interference with certain flavorings such as lemon, some products could not be reliably analyzed for spoilage and are marked "NA" for "Freshness" in the 3^rd column in the table below or with a "partial pass" when one of the two compounds that indicate spoilage could be reliably measured.

Range of EPA + DHA Concentrations and Pill Sizes
As shown in the bar graph below (and in more detail in the Results table), amounts of omega-3 fatty acids per serving ranged from as much as 2,840 mg in teaspoon of Nordic Naturals Ultimate Omega down to 234 mg in a spray of Thinkmist Prenatal DHA and just 120 mg in a softgel of Member's Mark [Sam's Club] Extra Strength Krill Oil.

The bar graph also shows that some supplements are more highly concentrated in omega-3s than others, i.e., they contain omega-3s and little other oil (the yellow or orange part of the bars). Concentration depends on the source of the omega-3s, how the oil is processed, and the amounts of other oils included in the supplement. A more concentrated product allows you to consume a smaller amount of oil (e.g., fewer or smaller pills) to get the same amount omega-3s. For example, Omegavia Ultraconcentrated Omega-3 and Wild Fish Oil each provide about 1,100 mg of omega-3s per serving, but Omegavia does this in about 1,200 grams of fish oil versus about 4.5 grams (4,500 mg) of oil in a serving of Wild Fish Oil. This is why it's important to focus on the amount of omega-3s, rather than the total amount of fish oil, in a supplement.

Another way to compare the concentrations of products is to refer to the bottom of the fourth column in the Results table below, which provides the relative concentration of EPA and DHA in the listed amount of fish oil or other marine oil. If a product did not list the total amount of fish/marine oil, we used the claimed amount of fat or, if that was not listed, the measured weight of its contents.

Relative Concentrations of EPA + DHA in Tested Products:
- Extremely high: 80% to 90% (Note: This is the concentration of the prescription medications Lovaza and Epanova.)
- Very high: 65% to 79%
- High: 45% to 64%
- Moderate: 24% to 44%
- Low: 17% to 23%
- Very low: 8% to 16%

When Size Matters
If you have trouble swallowing large softgels, the second column of the results table also includes descriptions of the pill size. As some softgels are more narrow than others, and this can make swallowing a bit easier, we've also indicated which are "narrow" (i.e., a width/length ratio <0.37). Most of the supplements were softgels and ranged in length from just under one-half inch to over one inch in length. These are fairly large sizes compared to capsules of other types of supplements. The tested softgels are grouped by length as follows:

Softgel Sizes by Length: (Oblong shape unless noted otherwise)
- Very large: over 25.4 mm (> 1 inch)
- Large: up to 25.4 mm (1 inch)
- Medium/Large: up to 19 mm (3/4 inch)
- Medium: up to 12.7 mm (1/2 inch)

Although ConsumerLab.com did not find any products to be spoiled, keep in mind that, due to chemical interferences, many products with flavorings, such as lemon, or products that are deeply colored, such a krill oil, could not be tested for spoilage and are marked "N/A" in the "Freshness" column in the table below. If you want to be sure a product was fresh, choose one that has a check mark in the "Freshness" column.

Cost
To help you compare the cost of products and determine those that offer the best value, the graph below (and 5th column of the Results table) shows the cost to obtain 500 mg of EPA and/or DHA from each product based on the price we paid. After all, it's not how much "oil" that matters, but how much actual EPA and/or DHA you get. Keep in mind that prices may vary across merchants and your cost per serving will depend on how large a dose of EPA and/or DHA you choose to take -- which can range from as little as about 25 mg to more than 5,000 mg per day (see Dosage information). Krill oils tend to be more expensive than fish oils, and products with additional ingredients or special formulations (such as dog chews) tend to cost more.

Top Picks:

Below are our Top Picks for fish and marine oils that provide high quality and the best value within their category of tested products.

Fish oil in softgels is generally the least expensive way to get good-quality EPA and DHA. If you just want to be sure you're getting a decent amount of EPA and DHA (perhaps because you don't eat fish) such as 250 mg to 499 mg, you can choose one with a moderate or high concentration. If you need larger amounts such as 500 mg to1,000 mg or even as much as 3,000 mg to 4,000 mg (perhaps to lower triglyceride levels — although beware of an increased risk of atrial fibrillation), consider products with very or extremely high concentrations.

If you want to reduce the chance of fishy burps after taking fish oil, choose a capsule or softgel that passed freshness testing and is enteric-coated, which is designed to release the oil in the small intestine rather than in the stomach. However, it's theoretically possible that this could somewhat decrease absorption of omega-3s if it reduces the time during which omega-3s mix in the small intestine with bile acids which cause the oil to be emulsified (broken into smaller droplets), making absorption easier. So, if fish burps are not a problem for you, you may be better off choosing a product that is not enteric-coated.

— Moderate concentration: If cost is more of an issue than the size and number of pills you take, our Top Pick is Kirkland Signature [Costco] Fish Oil 1000 mg, which provides 250 mg of EPA plus DHA per softgel as moderately concentrated fish oil. The cost is just 2 cents per softgel, making it, by far, the most economical product. In addition, although not stated on the label, its omega-3s appear to be in the triglyceride form and it is not enteric-coated, so you're likely to get the best absorption.

— High concentration: If you want a slightly higher amount of omega-3s (about 300 mg) from a smaller capsule than Kirkland's, you can spend 8 cents a pill for Life Extension Omega Foundations Super Omega-3 EPA/DHA With Sesame Lignans & Olive Extract. The fish oil appears to be in the ethyl ester form and the softgel is not enteric-coated.

— Very/Extremely high concentration: Now, if you want a very or extremely concentrated fish oil, allowing you to get the most omega-3s with the least amount of total oil and pills, our Top Pick is GNC Triple Strength Fish Oil (1,000 mg of EPA and DHA per softgel for 27 cents). Each large softgel, which is enteric-coated, provides 734 mg of EPA and 266 mg of DHA, which seem to be in the ethyl ester form. At just a few cents more, another good choice is Nature Made Fish Oil 1,400 mg, providing 683 mg of EPA and 252 mg DHA in the ethyl ester form for 33 cents per enteric-coated softgel. Similar to these is Omegavia Ultra Concentrated Omega-3, which is also enteric-coated but in the triglyceride form although it costs more -- 46 cents.

Although not among the products most recently tested, be aware that you can get a similar amount of EPA and DHA at even lower cost (12 cents per softgel) from another highly-concentrated product, Spring Valley [Walmart] Maximum Care Omega-3 2000 mg, which we have tested and approved in the past. Each softgel provides 955 mg of EPA and DHA in the ethyl ester form and the softgel is not enteric coated.

Fish Oil Supplements Comparable to Prescription Omega-3s
Very and extremely highly concentrated omega-3s are not only sold as supplements, but some versions are approved as drugs for lowering elevated triglycerides. As shown in the table below, supplements can provide approximately the same omega-3s as prescription drugs at a lower cost. Note, however, that prescription drugs are held to higher standards than fish oil dietary supplements, including the clinical demonstration of safety and efficacy and more rigorous manufacturing standards and oversight. This should be considered when comparing products.

Attention has focused on the EPA-only drug Vascepa (icosapent ethyl), as it was shown to reduce the risk of cardiovascular disease in people with elevated levels of triglycerides. Vascepa claims to be 96% EPA, providing 960 mg of EPA per capsule; two of these are taken twice daily with meals. The cash price for each capsule is about $2.50, or $10 per day. (On May 22, 2020, the FDA approved a generic competitor to Vascepa made by Hikma Pharmaceuticals. Its launch has not been announced, apparently due to an ongoing patent dispute).

You can get similar amounts of EPA in a single large softgel of Carlson Elite EPA GEMS as in Vascepa. Carlson's softgels provide 1,000 mg of EPA and 16.5 mg of DHA, which appear to be in the ethyl ester form, like Vascepa. However, Vascepa costs about $2.50 per capsule versus 50 cents for Carlson — one-fifth the price of Vascepa. Like Vascepa, Carlson's capsule is not enteric-coated.

Omegavia EPA provides amounts of EPA and DHA similar to that in Carlson and Vascepa but in the triglyceride form and the softgel is enteric-coated. These softgels are also smaller, so you need to take more of them, although the cost for omega-3s is a little less than from Carlson.

If you are looking for a fish oil supplement similar to prescription Lovaza (465 mg EPA and 375 mg DHA in the ethyl ester form), Pure Encapsulations O.N.E. Omega provides a bit more -- 600 mg of EPA and 400 mg DHA per large softgel -- for 97 cents, although in the triglyceride form (so it may actually be better absorbed than the omega-3s in Lovaza). An even closer match to Lovaza and at lower cost is a product we tested and approved in the past, Spring Valley [Walmart] Maximum Care Omega-3 2000 mg. It provides even more EPA and almost as much DHA but at the very low cost of just 12 cents per softgel, which, as shown in the table below, is only about 1/10^th the cost of generic Lovaza.

Comparison of Omega-3 Prescription Drugs to
Very or Extremely Concentrated Supplements Approved by ConsumerLab.com

Product	EPA and DHA Per 1 Capsule or Softgel	Cost Per Capsule or Softgel^**1	Rx Dose and Compar-able Dose^2	EPA and DHA Per Day	Cost Per Day	Chemical Form/Other
Vascepa (PRESCRIPTION)	EPA: 960 mg DHA: <40 mg (High EPA)	$2.50^3	4 capsules	EPA: 3,840 mg DHA: <160 mg	$10.00	Ethyl ester
Carlson Elite EPA Gems	EPA: 1,000 mg DHA: 16.5 mg (High EPA)	$0.50	4 softgels	EPA: 4,000 mg DHA: 66 mg	$2.00	Appears to be ethyl ester
Omegavia EPA 500	EPA: 500 mg DHA: 21.2 mg (High EPA)	$0.22	7 softgels	EPA: 3,500 mg DHA: 148.4 mg	$1.54	Triglyceride Enteric-coated
Lovaza (PRESCRIPTION)	EPA: 465 mg DHA: 375 mg (EPA/DHA)	$1.83^3 (Generic: $1.16^3)	4 capsules	EPA: 1,860 mg DHA: 1,500 mg	$7.32 (Generic: $4.64)	Ethyl ester
Solgar Triple Strength Omega 3 950 mg**	EPA: 504 mg DHA: 378 mg (EPA/DHA)	$0.29^3	4 softgels	EPA: 2,016 mg DPA: 1,512 mg	$1.16	Ethyl ester
Pure Encapsulations O.N.E. Omega	EPA: 600 mg DHA: 400 mg (EPA/DHA)	$0.97	4 softgels	EPA: 2,400 mg DHA: 1,600 mg	$3.86	Triglyceride
Spring Valley Maximum Care Omega-3 2000 mg**	EPA: 645 mg DHA: 310 mg (Mostly EPA)	$0.12^3	4 softgels	EPA: 2,580 mg DHA: 1,240 mg	$0.46	Ethyl ester
Nature Made Fish Oil 1,400 mg	EPA: 683 mg DHA: 252 mg (Mostly EPA)	$0.33	4 softgels	EPA: 2,732 mg DHA: 1,008 mg	$1.33	Ethyl ester Enteric-coated
* Tested by ConsumerLab.com in 2016. ** Tested by ConsumerLab in 2018 or 2019. **1 Prices are from 2020 and may vary over time. 2 Comparable doses from supplements were calculated by ConsumerLab to provide amounts of EPA and DHA comparable to those from prescription drugs; they are typically greater than the suggested serving sizes indicated on the supplements.

Fish oil liquids, e.g. from bottles, are a good option if you don't like to swallow capsules or if you need to easily adjust dosage. You can, however, cut this dose to just a quarter teaspoon and still get more EPA and DHA than many softgels. Our overall Top Pick for liquids is Wild Fish Oil. One teaspoon provides 1,053.7 mg of EPA and DHA and costs only 27 cents.

If you want to minimize how much oil you need to swallow, pay more and get Nordic Naturals Ultimate Omega — Lemon Flavor, our Top Pick for highly concentrated fish oil. Just half a teaspoon will provide 1,235 mg of EPA and DHA, although it will cost 63 cents.

One potential downside of concentrated fish oils is that, to focus on omega-3s, much of the omega-7s are removed. You can see this difference when comparing the amounts of omega-7 in one teaspoon of Wild Fish Oil (549.6 mg) versus Nordic Naturals (131.6 mg).

Be sure to keep liquid fish oils refrigerated as they begin to spoil once opened, and shake the bottle before each use.

Krill oil is generally the most expensive source of omega-3 fatty acids. Our Top Pick for krill oil is Member's Mark [Sam's Club] Extra Strength Krill Oil. One of these medium/large softgels provides 64 mg of EPA and 30 mg of DHA for 15 cents. In terms of getting omega-3s from krill oil, Member's Mark was less than half the cost of the other krill oils tested, Kori Pure Antarctic Krill Oil and Viva Naturals Antarctic Krill Oil. Member's Mark is essentially identical in its ingredients and quality to Schiff MegaRed and CVS Health Extra Strength 100% Pure Omega-3 Krill Oil, both of which were tested and Approved by CL in 2018 but are slightly more expensive than Member's Mark.

ConsumerLab.com also tested the amounts of phospholipids in these products, as phospholipids naturally occur with krill oil and appear to enhance absorption of EPA and DHA. Both products had the expected amounts. All krill products also claim amounts of astaxanthin, an antioxidant pigment which occurs in krill. As noted earlier, Viva Naturals claimed 1,600 mcg per 2 capsules but was found to contain only 1,012.6 mcg and, therefore, could not be Approved by CL, although this is still several times the amount in Member's Mark, which provides 150 mcg of phospholipids per softgel. Interestingly, CL has tested other krill oils in the past that contained much higher amounts -- hundreds of milligrams — of astaxanthin per softgel, but much of this was added and not natural to the krill oil. 

Algal oil is a good source of omega-3s — particularly DHA — and is assumed to be in the triglyceride form, which is likely good for absorption. CL's Top Pick is Deva Vegan Omega-3 DHA, which provided its claimed 200 mg of DHA per softgel costing 30 cents. CL found very little EPA — just 1.3 mg — but a fair amount of DPA (33.9 mg), another omega-3 fatty acid. Deva provided omega-3s at a slightly lower cost than the other algal oil that we tested, Freshfield Vegan Omega-3 EPA + DPA which, as noted earlier, was not Approved because it was inaccurately labeled, claiming 500 mg of total omega-3s but providing only 46.8% of that amount.

Prenatal supplements tend to have much higher DHA content than EPA due to DHA's role in brain development, although supplements with DHA have shown more benefit in terms of reducing colds, asthma, and allergy in offspring than providing cognitive benefits (see What It Does: During Pregnancy above). The lowest cost to obtain DHA was Whole Foods Market Prenatal DHA, which costs 36 cents per 2 softgel serving and is our Top Pick. Its suggested serving of 2 softgels provides 480 mg of DHA and 205 mg of EPA in the triglyceride form, and we found a significant amount of DPA (111.5 mg) as well. The other prenatal DHA product that we tested, Thinkmist Prenatal, a spray, costs about the same as Whole Foods per serving (1 spray), but provides less than half the amount of DHA (200 mg) and little EPA (just 8.5 mg) and DPA (only 17.2 mg). (You can find ConsumerLab.com's tests of prenatal multivitamins in the Multivitamin Review).

Children's supplements with fish oil, such as liquids, chewables, and gummies, tend to sell at premium prices because of their special, child-oriented formulations. This holds true for our Top Pick for children's supplements is Barlean's Omega Pals — Chirpin' Slurpin' Lemonade Flavor, which costs 46 cents per 1 ½ teaspoon serving. It is a slightly thick liquid that has a pleasant, somewhat sweet, lemony flavor that does a good job hiding the taste of fish oil. The suggested serving provides 330 mg of EPA and 210 mg of DHA, as well as some DPA and 215.4 mg of omega-7s. It is a bit more expensive than Oslomega Kids Omega-3 Fish Oil, but Oslomega is essentially just a softgel with a capsule that has a faint strawberry flavor, which children may not want to swallow. In addition, Barlean's Omega Pals can be given to children 1 year and older, while the Oslomega Kids fish oil softgels are suggested for only children 4 years and older.

Pet supplements need to be chosen with particular care, as one of the products CL tested in the past (2016), Amazing Nutritionals Omega 3 Chews, contained only tiny amounts of omega-3s -- even less than listed on the label. And, this year, Doctor's Foster + Smith Premium Plus Omega-3 For Dogs was "Not Approved" because it contained only 51% of its listed EPA and 44.2% of its listed DHA. Our Top Pick for dogs as well as cats is, hands down (or, better, paws down), Pet Honesty Wild Caught Omega-3 Fish Oil — For Dogs & Cats, which comes in a squeezable, pour-top bottle which, like all fish oil liquids, should be refrigerated after opening. The oil can be applied directly to pet food and costs just 6 cents per 530 mg of EPA and DHA, which is significantly less expensive than the Doctor's Foster + Smith's chews which provided only about 145 mg of EPA and DHA per chew that costs 25 cents.

DPA (the "other" omega-3 in fish oil)
The omega-3 DPA (as discussed elsewhere) may have some cardiovascular benefit. Amounts of DPA that we found per serving of each product are shown in the 2^nd column of the Results table below. The least expensive source of DPA was Wild Fish Oil (103.7 mg of DPA per teaspoon for 27 cents). Somewhat higher amounts were found in servings of two other more highly concentrated products, but at much greater cost for DPA: Nordic Naturals Ultimate Omega — Lemon Flavor (199 mg per teaspoon for $1.27) and USANA Biomega (128.8 mg per 2 softgels for 89 cents).

Omega-7 supplements
Omega-7 fatty acids are best obtained from fish oil or from a plant, such as sea buckthorn. One of the most commonly occurring omega-7s is palmitoleic acid. Although sometimes promoted for improving insulin sensitivity and lipid levels and having other benefits, there is no good clinical research to back this up. The product that provided by far the greatest amount of omega-7s (549.6 mg per teaspoon) was Wild Fish Oil, our Top Pick for Omega-7s.

Although not tested in this Review, in 2018 we tested one sea buckthorn product — New Chapter Sea Buckthorn Force, which passed our testing. It contained its listed 100 mg of omega-7s per vegetarian capsule (for 68 cents), and 77.9% of this was palmitoleic acid. However, the cost to obtain omega-7 from this product was significantly higher than from two omega-7 products CL tested two years earlier, which were SeabuckWonders Sea Buckthorn Oil Blend Omega-7 Complete (155 mg of omega-7s along with a range of other omega-3, -6, and -9 oils from seed oils in a softgel costing 33 cents) and Doctor's Best Omega-7 (roughly 200 mg of omega-7s per 54 cent softgel).

Green-lipped mussel oil has been promoted for containing "omega" fatty acids. Although not included in this year's testing, be aware that Omega XL, a proprietary blend that includes "green lipped mussel oil extract," was neither "Approved" nor "Not Approved" by ConsumerLab.com when tested in 2016 because it did not claim to contain a specific amount of omega-3 fatty acids: its label simply indicates that it "contains 30 free fatty acids including EPA, DHA, ETA and OTA." Each softgel, listed as containing 300 mg of a proprietary blend, was found to contain just 5.8 mg of EPA and 5.0 mg of DHA. The only substantial amount of omega fatty acids found were omega-9s (76 mg per capsule) nearly all of which was oleic acid, which may, at least in part, come from the "Extra Virgin Olive Oil" listed as an ingredient after "Green Lipped Mussel Oil Extract (PCSO-524®) containing Omega Fatty Acids" and before the only other listed ingredient "d-alpha Tocopherol (Vitamin E)." Many of the fish oil supplements provide a comparable amount of omega-9s per capsule (results not shown). It is somewhat surprising that a product named Omega XL provides relatively small amounts of omega fatty acids and a chemical profile similar to olive oil. The formulation in this product appears to be that of Lyprinol®, which is described as 50 mg of PCSO-524, 100 mg of oleic acid, and 0.225 mg of vitamin E according to the Lyprinol website. (Also see the information about Omega XL in the "What It Does" section.) The product is also fairly expensive -- $2 per 2 softgel serving.

Calamari oil — Although not included in this year's testing, in 2018 we tested one calamari (squid) oil product: Dr. Sinatra Omega Q Plus, which passed testing. A two softgel serving provided 200 mg of EPA and 350 mg of DHA and costs $1.43. It is a relatively expensive way to get omega-3 fatty acids, although it included vitamins B6 & B12, L-carnitine, and relatively modest amounts of CoQ10 and trans resveratrol. Be aware that the amounts of B6 and B12 in this product were much higher than you need, unless you are significantly deficient in these vitamins.

Test Results by Product:

Listed alphabetically below are the test results for 32 supplements containing omega-3 fatty acids (including two for pets). Seventeen of these were selected by ConsumerLab.com for review. Fifteen others (each indicated with a CL flask icon) were tested at the request of their manufacturers/distributors through CL's Quality Certification Program and are included for having passed testing.

The full list of ingredients is shown for each product in the last column on the right. All "Approved" products met their label claims for omega-3s, quality standards regarding lead, cadmium, and arsenic, were not spoiled, and, if labeled as "enteric coated," passed disintegration testing.

Results of ConsumerLab.com Testing of OMEGA-3 MARINE OIL SUPPLEMENTS

(Click arrows or swipe left or right to see all columns)

Approval Statusⓘ

Product Name

Fatty Acidsⓘ

Astaxanthin & Phospholipids (krill only)ⓘ

Freshnessⓘ

Heavy Metals

Suggested Serving on Label

Size of Pillⓘ

Concentration of EPA + DHAⓘ

Chemical Formⓘ

Cost for Suggested Serving

[Cost Per 500 mg of EPA + DHA]

Priced

Notable Features

Full List of Ingredients Per Serving

Fish Oil - Regular Softgels:

APPROVED

Comparable to Prescription Fish Oil

Carlson® Elite EPA Gems®

Dist. by Carlson Division of J.R. Carlson Laboratories, Inc.

$ Price Check

1 softgel

EPA: 1,000 mg ✔
DHA^F: 16.5 mg
DPA^F: 3.2 mg
Total Omega-3^F: 1,043.2 mg
Total Omega-7^F: 4.2 mg (<12.9% palmitoleic acid)

Total Oil: 1,300 mg

Freshness: Pass

Heavy Metals: Pass

Adults: take one soft gel once or twice daily at mealtime.

Large softgel

Very high concentration

Form not listed, but appears to be ethyl ester

$0.50/softgel

[$0.27 based on amount found]

$29.99/60 softgels

IFOS™ seal. Gluten Free. No Artificial Preservatives.

Precaution: Contains fish (anchovy, sardine and mackerel).

1 softgel
Calories 15, Total Fat 1.5 g, Fish Oil Concentrate [EPA (Eicosatetraenoic Acid) 1,000 mg] 1.3 g.

Other Ingredients: Soft gel shell (beef gelatin, glycerin, water), natural tocopherols.

APPROVED

Carlson® Maximum Omega 2000 - Natural Lemon Flavorⓘ

Dist. by Carlson Division of J.R. Carlson Laboratories, Inc.

2 softgels

EPA: 1,250 mg ✔
DHA: 500 mg ✔
DPA^F: 94.6 mg
Total Omega-3: 2,000 mg ✔
Total Omega-7^F: 6 mg (40.9% palmitoleic acid)


Total Oil: 2,600 mg

Freshness: Partial Pass

Heavy Metals: Pass

Adults: take two soft gels daily at mealtime.

Very large softgel

Very high concentration

Triglyceride

$0.80/2 softgels

[$0.23]

$35.99/90 softgels

igen Non-GMO Tested seal. Gluten-free. No Artificial Preservatives.

Precaution: Contains fish (anchovy, sardine, and mackerel).

2 softgels
Calories 30, Total Fat 2.5 g, Protein <1 g, Norwegian Fish Oil Concentrate [Total Omega-3 Fatty Acids [EPA (Eicosapentaenoic Acid) 1,250 mg, DHA (Docosahexaenoic Acid) 500 mg] 2,000 mg] 2.6 g.

Other Ingredients: Soft gel shell (beef gelatin, glycerin, water), natural mixed tocopherols, d-alpha tocopherol, natural flavors.

APPROVED

Garden of Life® Minami Platinum Omega-3 Fish Oil - Orange Flavor 

Dist. by Garden of Life LLC

$ Price Check

1 softgel

EPA: 756 mg ✔
DHA: 228 mg ✔
DPA^F: 24.3 mg
Total Omega-3: 1,080 mg ✔
Total Omega-7^F: 1.5 mg (54.5% palmitoleic acid)

Total Oil: 1,100 mg

Freshness: Pass

Heavy Metals: Pass

Adults, take 1 softgel per day with water.

Very large softgel

Very high concentration

Triglyceride

$0.72/softgel

[$0.37]

$43.39/60 softgels

1 softgel

Vitamin D 25 mcg (1,000 IU)

Made without dairy ingredients, peanuts, tree nuts of shellfish. No artificial colors or preservatives.

Precaution: Contains: Fish, soy. Manufactured in a facility that also processes peanut and tree nuts.

1 softgel
Calories 10, Calories from Fat 10, Total Fat 1 g, Saturated Fat 0 g, Unsaturated Fat 1 g, Trans Fat 0 g, Vitamin D (as D3) 25 mcg (1,000 IU), Total Omega-3 Fatty Acids [EPA (Eicosapentaenoic Acid) 756 mg, DHA (Docosahexaenoic Acid) 228 mg, Other Omega-3s 96 mg] 1.1 g, more...

APPROVED

Top Pick

for Moderate Concentration Softgel

Kirkland Signature™ [Costco] Fish Oil 1,000 mg

Dist. by Costco Wholesale Corporation

1 softgel

EPA + DHA: 250 mg ✔
EPA^F: 142.9 mg
DHA^F: 141.9 mg
DPA^F: 23.1 mg
Total Omega-3^F: 360.8 mg
Total Omega-7^F: 86.6 mg (72.8% palmitoleic acid)

Total Oil: 1,000 mg

Freshness: Pass

Heavy Metals: Pass

Take one (1) softgel two times daily with a full glass of water, preferably with a meal.

Large (narrow) softgel

Moderate concentration

Form not listed, but appears to be triglyceride

$0.02/softgel

[$0.04 based on amount found]

$9.99/400 softgels

USP Dietary Supplement Verified® seal. No Artificial Colors. No Artificial Flavors. No Yeast or Gluten.

Precaution: Contains: Fish (Mackerel, Anchovy, Menhaden, Herring, Sardine).

1 softgel
Calories 10, Total Fat 1 g, Cholesterol 10 mg, Fish Oil [Omega-3 Fatty Acids (EPA+DHA) 250 mg, Other Omega-3 Fatty Acids 50 mg] 1,000 mg.

Ingredients: Fish Oil, Gelatin (Porcine), Glycerin, Water, Tocopherols.

APPROVEDⓘ

Top Pick

for High Concentration Softgel

Life Extension® Super Omega-3 

Dist. by Quality Supplements and Vitamins, Inc.

4 softgels

EPA: 700 mg ✔
DHA: 500 mg ✔
DPA^F: 73 mg
Total Omega-3^F: 1,389.3 mg
Total Omega-7^F: 58.4 mg (28.4% palmitoleic acid)

Total Oil: 2,000 mg

Freshness: Pass

Heavy Metals: Pass

Take four (4) softgels twice daily with meals, or as recommended by a healthcare practitioner.

Large (narrow) softgel

High concentration

Form not listed, but appears to be ethyl ester

$0.35/4 softgels

[$0.15]

$21.00/240 softgels

4 softgels

Polyphen-Oil™ olive extract 300 mg, sesame seed lignan extract 10 mg

IFOS™ seal. Non-GMO.

[Note: We tested Life Extension's item number 01986. It sells a similar product (Item # 01982) with the same name but with a suggested serving size of 2 softgels, rather than 4, which has a different list of "Other Ingredients." We did not test that product.]

4 softgels
Calories 25, Total Fat 2.5 g, Cholesterol <5 mg, Pure+™ Wild Fish Oil Concentrate [Yielding: EPA (eicosapentaenoic acid) 700 mg, DHA (docosahexaenoic acid) 500 mg] 2,000 mg, Polyphen-Oil™ Olive extract (fruit and leaf) [providing 19.5 mg polyphenols, 5.2 mg hydroxytyrosol/ tyrosol, 4.4 mg verbascoside/ oleuropein] 300 mg, Sesame seed lignan extract 10 mg, more...

APPROVEDⓘ

Naturelo® Omega-3 Triglyceride Fish Oil

Dist. by Naturelo Premium Supplements

1 softgel

EPA: 729 mg ✔
DHA: 275 mg ✔
DPA^F: 30.4 mg
Total Omega-3: 1,100 mg ✔
Total Omega-7^F: 6.7 mg (89.8% palmitoleic acid)

Total Oil: 1,326 mg

Freshness: Partial pass

Heavy Metals: Pass

Adults take one (1) softgel with a meal and a full glass of water.

Very large (narrow) softgel

Very high concentration

Triglyceride

$0.47/softgel

[$0.23]

$27.95/60 softgels

No GMOs. Does Not contain GMOs, soy, gluten, yeast, dairy, eggs, corn, shellfish, coloring, artificial flavoring or preservatives.

1 softgel
Calories 15, Calories from Fat 10, Total Fat 1.5 g, Molecularly Distilled Fish Oil [Total Omega-3 Fatty Acids [Eicosapentaenoic Acid (EPA) 729 mg, Docosahexaenoic Acid (DHA) 275, Other Omega-3 Fatty Acids 96 mg] 1,100 mg] 1,326 mg.

Ingredients: Purified Fish Oil, more...

APPROVED

Also APPROVED for CoQ10

Nutrifii Omega-Q™ⓘ

Dist. by Ariix

1 softgel

EPA: 295 mg ✔
DHA: 235 mg ✔
DPA^F: 52.8 mg
Total Omega-3: 530 mg ✔
Total Omega-7^F: 22.1 mg (57.1% palmitoleic acid)

Total Oil^F: 887.6 mg

Freshness: NAⓘ

Heavy Metals: Pass

Take 1 softgel twice daily, preferably with meals.

Large softgel

Moderate concentration

Form not listed, but appears to be ethyl ester

$1.26/softgel

[$1.19]

$70.70/56 softgels

1 softgel

CoQ10 20 mg

1 softgel
Omega-3 Fatty Acids (EPA - 295 mg, DHA - 235 mg) 530 mg, Coenzyme Q10 20 mg.

Other Ingredients: Fish Oil, Gelatin, Glycerin, Extra Virgin Olive Oil, Lemon Oil, Carob Bean Extract.

APPROVED

NutriGold® Triple Strength Omega-3 Fish Oil 

Dist. by NutriGold Inc.

2 softgels

EPA: 1,450 mg ✔
DHA: 550 mg ✔
DPA^F: 29 mg
Total Omega-3: 2,100 mg ✔
Total Omega-7^F: 12.6 mg (78.7% palmitoleic acid)

Total Oil: 2,600 mg

Freshness: Pass

Heavy Metals: Pass

Adults take two (2) softgels daily with food, or as directed by a healthcare professional.

Very large softgel

Very high concentration

Triglyceride

$0.75/2 softgels

[$0.19]

$22.38/60 softgels

IFOS™ seal. ConsumerLab.com seal. Certified Sustainable Seafood MSC™ seal. Non GMO. Verified free of corn, egg, gluten, milk, peanut, shellfish, and soy allergens by an independent lab. No magnesium stearate, stearic acid, dioxides, sulfate, artificial ingredients, more...

2 softgels
Calories 25, Total Fat 2.5 g, Purified Fish Oil (from Alaska Pollock) [Total Omega-3 Fatty Acids [EPA (Eicosapentaenoic Acid) 1,450, DHA (Docosahexaenoic Acid) 550 mg, Other Omega-3s 100 mg] 2,600 mg.

Other Ingredients: Softgel shell, more...

APPROVED

Pure Encapsulations® O.N.E.™ Omega

Dist. by Pure Encapsulations

1 softgel

EPA: 600 mg ✔
DHA: 400 mg ✔
DPA^F: 44.4 mg
Total Omega-3^F: 1,133.3 mg
Total Omega-7^F: 2.8 mg (66.7% palmitoleic acid)

Total Oil: 1,250 mg

Freshness: Pass

Heavy Metals: Pass

Take 1 capsule daily, with a meal.

Large softgel

Extremely high concentration

Triglyceride

$0.97/softgel

[$0.48]

$57.90/60 softgels

Gluten-free & Non-GMO.

Precaution: Contains fish (anchovies, jack, herring, smelt, salmon, mackerel, squid).

1 softgel
Calories 10, Total fat 1 g, Fish oil concentrate (from anchovies, jack, herring, smelt, salmon, mackerel, squid) [providing: EPA (Eicosapentaenoic acid) 600 mg, DHA (docosahexaenoic acid) 400 mg] 1,250 mg.

Other Ingredients: Gelatin capsule, more...

APPROVED

Puritan's Pride® Triple Omega 3-6-9 

Mfd. by Puritan's Pride, Inc.

3 softgels

EPA^F: 213.4 mg
DHA^F: 109.8 mg
DPA^F: 29.8 mg
Total Omega-3: 1,360 mg ✔
Linoleic Acid + GLA: 328 mg ✔
Oleic acid: 268 mg ✔
Total Omega-7^F: 45.2 mg (67.3% palmitoleic acid)

Total Oil: 3,600 mg

Freshness: Pass

Heavy Metals: Pass

For adults, take three (3) softgels daily, preferably with a meal.

Large softgel

Very low concentration

Form not listed, but appears to be triglyceride

$0.65/3 softgels

[$1.00 based on amount found]

$12.99/60 softgels

No Artificial Color, Flavor or Sweetener, No Preservatives, No Sugar, No Starch, No Milk, No Lactose, No Gluten, No Wheat, No Yeast, No Shellfish, Sodium Free.

Precaution: Contains fish (anchovy, herring, mackerel, sardine) ingredients.

3 softgels
Calories 40, Total Fat 3.5 g, Saturated Fat 0.5 g, Polyunsaturated Fat 2 g, Monounsaturated Fat 1 g, Cholesterol 10 mg, Maximum Strength Triple Omega 3, 6, 9 Proprietary Blend Organic Flaxseed Oil, Ester-Omega® Fish Oil, Borage Seed Oil [Typical Fatty Acid Profile: Omega-3, more...

APPROVEDⓘ

Sisu Wild Fish Oil Omega 1,000 mg

Dist. by Sisu

1 softgel

EPA: 400 mg ✔
DHA: 200 mg ✔
DPA^F: 30.8 mg
Total Omega-3^F: 686.6 mg
Total Omega-7^F: 10.9 mg (9.6% palmitoleic acid)

Total Oil: 1,000 mg

Freshness: Partial pass

Heavy Metals: Pass

Take 3 capsules daily or as directed by a healthcare practitioner (capsules are meant to be swallowed, not chewed).

Large (narrow) softgel

High concentration

Form not listed, but appears to be ethyl ester

$0.30/softgel

[$0.25]

$35.63/120 softgels

1 softgel

Vitamin E 6.7 mg AT

Non-GMO. Contains no dairy, wheat, gluten, corn, sweeteners, artificial preservatives or flavors. All Sisu fish oils meet or exceed Canadian standards for freshness and purity.

1 softgel
Fish Oil (body oils from anchovy, sardine and/or mackerel) [providing 400 mg EPA (eicosapentaenoic acid) and 200 mg DHA (docosahexaenoic acid)] 1,000 mg, Vitamin E (d-alpha-tocopherol) [from sunflower oil, equivalent to 10 IU vitamin E activity] 6.7 mg AT, more...

APPROVEDⓘ

USANA® Biomega™

Mfd. by USANA Health Sciences, Inc.

2 softgels

EPA: 580 mg ✔
DHA: 470 mg ✔
DPA^F: 128.8 mg
Total Omega-3: 1,200 mg ✔
Total Omega-7^F: 18.4 mg (56% palmitoleic acid)

Total Oil: 2,000 mg

Freshness: Partial pass

Heavy Metals: Pass

Take two (2) capsules daily, preferably with food.

Large softgel

High concentration

Form not listed, but appears to be ethyl ester

$0.89/2 softgels

[$0.42]

$35.63/56 softgels

2 softgels

Vitamin D3 5 mcg

Precaution: Contains: Soy.

2 softgels
Vitamin D3 (as Cholecalciferol) 5 mcg, Fish Oil Concentrate [Total Omega-3 Fatty Acids 1,200 mg, EPA (Eicosapentaenoic Acid) 580 mg, DHA (Docosahexaenoic Acid) 470 mg] 2,000 mg.

Other Ingredients: Gelatin, Glycerin, more...

APPROVEDⓘ

Vitacost Synergy® Super EPA Omega-3

Dist. by Vitacost.com®

2 softgels

EPA: 1,200 mg ✔
DHA: 300 mg ✔
DPA^F: 37.6 mg
Total Omega-3: 1,600 mg ✔
Total Omega-7^F: 2.7 mg (71.4% palmitoleic acid)

Total Oil^F: 1,956.8 mg

Freshness: NAⓘ

Heavy Metals: Pass

Take 2 softgels daily with food or as directed by a healthcare professional.

Large softgel

Very high concentration

Ethyl ester

$0.53/2 softgels

[$0.18]

$15.99/60 softgels

Free of: Milk, Eggs, Peanuts, Tree Nuts, Crustacean Shellfish, Gluten, Titanium Dioxide. Sustainability Sourced.

2 softgels
Calories 20, Calories from Fat 15, Total Fat 2 g, Omega-3 Fatty Acids (derived from purified fish oil) [Eicosapentaenoic Acid (EPA) 1,200 mg, Docosahexaenoic Acid (DHA) 300 mg] 1,600 mg.

Other Ingredients: Gelatin, Vegetable Glycerin, Water, more...

Fish Oil - Enteric Coated Softgels:

APPROVED

Cardio Tabs Enteric-Coated Omega-3

Dist. by Good Things Health

3 enteric-coated softgels

EPA: 330 mg ✔
DHA: 675 mg ✔
DPA^F: 80.3 mg
Total Omega-3: 1,100 mg ✔
Total Omega-7^F: 45.1 mg (47.1% palmitoleic acid)

Total Oil: 1,950 mg

Freshness: Partial pass

Heavy Metals: Pass

For adults, take three (3) softgels daily or as recommended by your healthcare provider, preferably with a meal.

Medium/large enteric-coated softgel

High concentration

Triglyceride

$0.62/3 enteric-coated softgels

[$0.31]

$36.95/180 enteric-coated softgels

Friend of the Sea® seal. Pharmaceutical Grade. Free Of: Yeast, wheat, gluten, milk/dairy, sodium, sugar, starch, artificial coloring or preservatives.

Precaution: Contains: Fish (Anchovy, Sardine, and/or Mackerel).

3 enteric-coated softgels
Calories (energy) 20, Total Fat 2 g, Cholesterol <5 mg, Concentrated Omega-3 Marine Oil [Total Omega-3 Fatty Acids [EPA (Eicosapentaenoic Acid) 330 mg, DHA (Docosahexaenoic Acid) 675 mg, Additional Omega-3 Fatty Acids 100 mg] 1,100 mg] 1,950 mg, more...

APPROVED

Top Pick

for Very High Concentration Softgel

GNC Triple Strength Fish Oil

Dist. by General Nutrition Corporation

1 enteric-coated softgel

EPA: 734 mg ✔
DHA: 266 mg ✔
DPA^F: 80.3 mg
Total Omega-3: 1,065 mg ✔
Total Omega-7^F: 45.1 mg (47.1% palmitoleic acid)

Total Oil^F: 1,368 mg

Freshness: Pass

Heavy Metals: Pass

Take one softgel capsule daily with food.

Large enteric-coated softgel

Very high concentration

Form not listed, but appears to be ethyl ester

$0.27/enteric-coated softgel

[$0.14]

$32.49/120 enteric-coated softgel

No Sugar, No Starch, No Artificial Colors, No Artificial Flavors, No Preservatives, Sodium Free, No Wheat, Gluten Free, No Corn, No Dairy, Cholesterol Free.

Precaution: Contains: Soybeans and Fish (Anchovy, Mackerel, Sardine, Smelt, Salmon, Tuna, Cod or a Combination Thereof).

1 enteric-coated softgel
Calories 15, Total Fat 1.5 g, Cholesterol 0 mg, Total Omega-3s [Total EPA + DHA [EPA (Eicosapentaenoic Acid) Omega-3 734 mg, DHA (Docosahexaenoic Acid) Omega-3 266 mg] 1,000 mg, Other Omega-3s 65 mg] 1,065 mg.

Ingredients: Fish Oil, Softgel & Enteric Coating (Gelatin, Glycerin, Stearic Acid, Sodium Alginate, more...

APPROVED

GNC Triple Strength Fish Oil Mini 

Dist. by General Nutrition Corporation

2 mini enteric-coated softgels

EPA: 734 mg ✔
DHA: 266 mg ✔
DPA^F: 38.8 mg
Total Omega-3: 1,065 mg ✔
Total Omega-7^F: 10.3 mg (20% palmitoleic acid)

Total Oil^F: 1,371 mg

Freshness: Pass

Heavy Metals: Pass

Take two mini softgel capsules daily with food.

Medium/large mini enteric-coated softgel

Very high concentration

Form not listed, but appears to be ethyl ester

$0.42/2 mini enteric-coated softgels

[$0.21]

$49.99/240 mini enteric-coated softgels

Gluten Free. No Sugar, No Starch, No Artificial Colors, No Artificial Flavors, NO Preservatives, Sodium Free, No Wheat, Gluten Free, No Corn, No Dairy, Cholesterol Free.

Precaution: Contains: Soybeans and Fish (Anchovy, Mackerel, Sardine, Smelt, Salmon, Tuna, Cod or a Combination Thereof).

2 mini enteric-coated softgels
Calories 15, Total Fat 1.5 g, Cholesterol 0 mg, Total Omega-3s [Total EPA + DHA [EPA (Eicosapentaenoic Acid) Omega-3 734 mg, DHA (Docosahexaenoic Acid) Omega-3 266 mg] 1,000 mg, Other Omega-3s 65 mg] 1,065 mg, more...

APPROVEDⓘ

Nature Made® Fish Oil 1,400 mg

Dist. by Nature Made Nutritional Products

1 enteric-coated softgel

EPA: 683 mg ✔
DHA: 252 mg ✔
DPA^F: 35.7 mg
Total Omega-3: 1,000 mg ✔
Total Omega-7^F: 9.2 mg (<6.3% palmitoleic acid)

Total Oil: 1,400 mg

Freshness: Pass

Heavy Metals: Pass

Adults, take 1 softgel daily with water and a meal for optimal absorption.

Large enteric-coated softgel

Very high concentration

Ethyl ester

$0.33/enteric-coated softgel

[$0.18]

$14.99/45 enteric-coated softgel

No Color Added. No Artificial Flavors. Gluten Free.

1 enteric-coated softgel
Calories 15, Total Fat 1.5 g, Polyunsaturated Fat 1 g, Cholesterol 15 mg, Total Carbohydrate less than 1 g, Omega-3 Concentrate from Fish Oil [Total Omega-3 Fatty Acids [EPA (Eicosapentaenoic Acid) Omega-3 683 mg, DHA (Docosahexaenoic Acid) 252 mg, Other Omega-3 65 mg] 1,000 mg] 1,400 mg, more...

APPROVED

Omegavia™ EPA 500

Dist. by Innovix Pharma Inc.

$ Price Check

1 enteric-coated capsule

EPA: 500 mg ✔
DHA^F: 21.2 mg
DPA^F: 4.2 mg
Total Omega-3^F: 537.4 mg
Total Omega-7^F: 0.4 mg (<66.7% palmitoleic acid)

Total Oil^F: 659.1 mg

Freshness: Pass

Heavy Metals: Pass

Take 2 to 6 capsules per day.

Medium/large enteric-coated capsule

Very high concentration

Triglyceride

$0.22/enteric-coated capsule

[$0.22 based on amount found]

$26.89/120 enteric-coated capsules

IFOS™ seal. Does Not Contain: Dairy, eggs, corn, shellfish, tree nuts, peanuts, wheat/gluten, soy, sugar, GMO, yeast, Chinese ingredients, artificial colors or flavors.

Precaution: Source: Sustainably sourced Anchovy, Sardine, and Mackerel (Peru and Chile).

1 enteric-coated capsule
Calories 5, Calories from Fat 5, Total Fat 0.5 g, EPA Omega-3 [Eicosapentaenoic Acid] 500 mg.

Other Ingredients: Fish Gelatin, Vegetable Glycerin, Purified Water, Vegetable Enteric Coating (Alginate, Stearic Acid), Sunflower Tocopherols, Rosemary Extract.

APPROVED

Omegavia™ Ultra Concentrated Omega-3 

Dist. by Innovix Pharma Inc.

$ Price Check

1 enteric-coated softgel

EPA: 780 mg ✔
DHA: 260 mg ✔
DPA: 10 mg ✔
Total Omega-3: 1,105 mg ✔
Total Omega-7^F: 4.5 mg (27.3% palmitoleic acid)

Total Oil: 1,300 mg

Freshness: Pass

Heavy Metals: Pass

Take 1 to 4 softgels per day.

Large enteric-coated softgel

Extremely high concentration

Triglyceride

$0.46/enteric-coated softgel

[$0.22]

$27.89/60 enteric-coated softgels

IFOS™ seal. Does Not Contain: Dairy, eggs, corn, shellfish, tree nuts, peanuts, wheat/gluten, soy, sugar, GMO, yeast, Chinese ingredients, artificial colors or flavors.

Precaution: Source: Sustainably sourced fish oil from Anchovy, Sardine, and Mackerel (Peru/Chile).

1 enteric-coated softgel
Calories 15, Total Fat 1.5 g, Ultra Concentrated Oil (85% Omega-3) 1,300 mg, Total Omega-3 [EPA Omega-3 (Eicosapentaenoic Acid) 780 mg, DHA (Docosahexaenoic Acid) 260 mg, DPA (Docosapenta-enoic Acid) 10 mg, Other Omega-3 (SDA, ETA, ETE, ALA) 55 mg] 1,105 mg, more...

Fish Oil - Liquids:

APPROVEDⓘ

Top Pick

for High Concentration Liquid

Nordic Naturals® Ultimate® Omega - Lemon Flavor

Dist. by Nordic Naturals, Mfg.

$ Price Check

1 tsp [5 ml]

EPA: 1,460 mg ✔
DHA: 1,010 mg ✔
DPA^F: 199 mg
Total Omega-3: 2,840 mg ✔
Total Omega-7^F: 131.6 mg (18.8% palmitoleic acid)

Total Oil: 5,000 mg

Freshness: NAⓘ

Heavy Metals: Pass

One-half to one teaspoon daily, with food, or as directed by your health care professional or pharmacist.

Liquid in bottle

High concentration

Triglyceride

Taste: Light lemon flavor, faintly fishy

$1.27/tsp

[$0.26]

$61.16/8 fl oz [237 ml] bottle (approx. 48 servings)

Non GMO Verified. No gluten, milk derivatives, or artificial colors or flavors.

1 tsp
Calories 45, Total Fat 5 g, Saturated Fat 0 g, Trans Fat 0 g, Cholesterol 10 mg, Total Omega-3s [EPA (Eicosapentaenoic Acid) 1,460 mg, DHA (Docosahexaenoic Acid) 1,010 mg, Other Omega-3s 370 mg] 2,840 mg.

Ingredients: Purified deep sea fish oil (from anchovies and sardines), natural lemon flavor, d-alpha tocopherol (antioxidant), rosemary extract (a natural preservative).

APPROVED

Top Pick

for Liquid, also for Omega-7s

Wild Fish Oil

Dist. by Wild Foods Brand LLC

1 tsp [5 ml]

EPA^F: 509.6 mg
DHA^F: 544.1 mg
DPA^F: 103.7 mg
Total Omega-3: typically 1,000 mg (DHA, EPA, DPA) ✔
Total Omega-7^F: 549.6 mg (79% palmitoleic acid)

Total Oil: 4,500 mg

Freshness: Partial pass

Heavy Metals: Pass

No directions listed

Liquid in bottle

Moderate concentration

Form not listed, but appears to be triglyceride

Taste: Pleasant lemon flavor with a hint of rosemary and vanilla.

$0.27/tsp

[$0.13 based on amount found]

$24.95/16 fl oz [473 ml] bottle (approx. 94 servings)

Friend of the Sea® seal. Gluten Free. Sustainable. Non GMO. This Product Is Free From Artificial Color, Synthetic Flavor, Corn, Gluten (Wheat), Lactose (Dairy), Yeast, Added Sugar, Soy, Peanuts, Tree Nuts, Sesame, Eggs, Artificial Preservatives, Crustaceans.

Precaution: Contains: Fish (menhaden).

1 tsp
Calories 40, Calories from Fat 40, Total Fat 4.5 g, Saturated Fat 1.5 g, Trans Fat 0 g, Polyunsaturated Fat 1.8 g, Monounsaturated Fat 1.3 g, Cholesterol 0 mg, Sodium 0 mg, Total Carbohydrate 0 g, Protein 0 g. Typical EPA/DPA/DHA Per Serving: 1,000 mg.

Ingredients: OmegaActiv™ Fish Oil, Lemon Flavor, more...

Krill Oil:

APPROVED

Kori™ Pure Antarctic Krill Oilⓘ

Dist. by Epion Brands

2 softgels

EPA: 250 mg ✔
EPA^F: 80.5 mg
DHA^F: 154.2 mg
DPA^F: 3.5 mg
Total Omega-3^F: 305.3 mg
Total Omega-7^F: 115.3 mg (50.9% palmitoleic acid)
Phospholipids: 480 mg ✔
Astaxanthin: 120 mcg✔

Total Oil: 1,200 mg

Freshness: Pass

Heavy Metals: Pass

Take 2 softgels daily.

Medium/large softgel

Low concentration

Form not listed, but assumed to be phospholipid

$0.70/2 softgels

[$1.40]

$20.99/60 softgels

Certified Sustainable Seafood MSC seal. Not diluted with fish oil. No fishy burps. No artificial colors, flavors or preservatives. Non-GM) krill oil.

Precaution: Contains Shellfish (Krill).

2 softgels
Calories 10, Total Fat 1 g, Cholesterol 20 mg, Choline 60 mg, Krill Oil [Total EPA + DHA Omega-3 Fatty Acids 250 mg, Phospholipids 480 mg, Astaxanthin 120 mcg] 1,200 mg.

Other Ingredients: Capsule (Gelatin, Glycerin, Sorbitol, Purified Water).

APPROVED

Top Pick

for Krill Oil

Member's Mark™ [Sam's Club] Extra Strength Krill Oil

Dist. by Sam's West, Inc.

1 softgel

EPA: 64 mg ✔
DHA: 30 mg ✔
DPA^F: 1.4 mg
Total Omega-3: 120 mg ✔
Total Omega-7^F: 41.9 mg (44.5% palmitoleic acid)
Phospholipids: 200 mg ✔
Astaxanthin: 150 mcg (esterified) ✔

Total Oil: 500 mg

Freshness: Pass

Heavy Metals: Pass

Take one softgel daily with a meal.

Medium/large softgel

Low concentration

Form not listed, but assumed to be phospholipid

$0.15/softgel

[$0.76]

$22.97/160 softgels

Certified Sustainable Seafood MSC seal.

Precaution: Contains: Crustacean Shellfish (Krill).

1 softgel
Calories 5, Total Fat 0.5 g, Cholesterol 10 mg, Krill Oil [Omega-3 Fatty Acids [EPA (eicosapentaenoic acid) 64 mg, DHA (docosahexaenoic acid) 30 mg] 120 mg, Phospholipids 200 mg, Esterified Astaxanthin 150 mcg] 500 mg.

Other Ingredients: Gelatin Capsule (Gelatin, Glycerin, Purified Water, Ethyl Vanillin, Sorbitol).

NOT APPROVED

Viva Naturals Antarctic Krill Oil

Dist. by Viva Naturals Inc.

2 Caplique® capsules

EPA: 165 mg ✔
DHA: 90 mg ✔
DPA^F: 3.9 mg
Total Omega-3: 330 mg ✔
Total Omega-7^F: 104.9 mg (42.8% palmitoleic acid)
Phospholipids: 575 mg ✔
Astaxanthin: Claimed 1,600 mcg (esterified); Found only 1,012.6 mcg per serving (63.3% of listed amount)

Total Oil: 1,250 mg

Freshness: Pass

Heavy Metals: Found to contain 4.9 ppm total arsenic (8.3 mcg to 16.6 mcg per day). However, found to have less than 0.08 ppm inorganic arsenic.

Take 2 Caplique® capsules daily. For intensive use, more...

Large (narrow) Caplique® capsule

Low concentration

Form not listed, but assumed to be phospholipid

$0.80/2 Caplique® capsules

[$1.57]

$23.99/60 Caplique® capsules

IKOS seal. Non GMO. Gluten Free. Dairy Free. Does Not Contain Artificial Colors, Dairy, Gluten Or GMOs.

Precaution: Contains Fish (Tilapia And Basa) And Shellfish (Krill).

2 Caplique® capsules
Calories 10, Total Fat 1 g, Krill Oil (Euphausia superba, whole) [Providing: Total Omega-3 Fatty Acids [DHA (Docosahexaenoic acid) 90 mg, EPA (Eicosapentaenoic acid) 165 mg] 300 mg, Phospholipids 575 mg, Esterified astaxanthin 1.6 mg] 1,250 mg, more...

Vegetarian Source (Algal) Oil:

APPROVED

Top Pick

for Algal Oil

Deva® Vegan Omega-3 DHA 

Dist. by Dev Nutrition LLC

$ Price Check

1 vegan softgel

EPA^F: 1.3 mg
DHA: 200 mg ✔
DPA^F: 33.9 mg
Total Omega-3^F: 214.3 mg
Total Omega-7^F: 1.7 mg (44.1% palmitoleic acid)

Total Oil: 575 mg

Freshness: Partial pass

Heavy Metals: Pass

For adults, take one (1) vegan softgel daily, or as directed by a health care professional.

Medium/large vegan softgel

Moderate concentration

Form not listed, but appears to be triglyceride

$0.30/vegan softgel

[$0.72 based on amount found]

$26.86/90 vegan softgel

Vegan. Free of yeast, soy, wheat, gluten, hexane, dairy, egg, fish, shellfish and salt.

1 vegan softgel
Calories 5, Calories from Fat 5, Total Fat 0.5 g, Microalgae Oil [which typically provides: DHA (Docosahexaenoic Acid) [Ω-3] 200 mg] 575 mg.

Other Ingredients: Non-gmo corn starch, mid-oleic sunflower oil, purified water, vegetable glycerin, carrageenan, sorbitol, lemon oil, mixed tocopherols, silica; less than 1% of: canola oil, more...

NOT APPROVED

Freshfield Vegan Omega-3 DHA + DPA

Dist. by Freshfield Naturals, Inc.

1 veggie gel

EPA^F: 1.4 mg
DHA: >240 mg ✔ (Found: 227.6 mg)
DPA: >25 mg ✔ (Found: 40.8 mg)
Total Omega-3: Claimed 500 mg; Found only 233.9 mg per serving (46.8% of listed amount)
Total Omega-7^F: 1.8 mg (38.9% palmitoleic acid)

Total Oil^F: 505.1 mg

Freshness: Pass

Heavy Metals: Pass

Take 1-2 softgels daily with a meal, or as directed by your healthcare professional.

Medium/large veggie gel

Low concentration

Form not listed, but appears to be triglyceride

$0.40/veggie gel

[$0.87 based on amount found]

$23.99/60 veggie gels

Vegan. GMO Free.

1 veggie gel
Calories 10, Calories for fat 10, Total fat 1 g, Total Omega-3 Fatty Acids [DHA (Docosahexaenoic Acid) >240 mg, DPA (Docosapenta-enoic Acid) >25 mg] 500 mg.

Ingredients: Algal oil (Schizochytrium sp. algae), purified water, modified food starch, more...

Prenatal Products:

APPROVED

Thinkmist™ Prenatal DHA

Dist. by Ddrpos Company

1 spray [0.3 ml]

EPA: 8.5 mg ✔
DHA: 200 mg ✔
DPA^F: 17.2 mg
Total Omega-3: 234.3 mg ✔
Total Omega-7^F: 0.4 mg (66.7% palmitoleic acid)

Total Oil^F: 276 mg

Freshness: NAⓘ

Heavy Metals: Pass

Administer 1 spray daily directly onto food or drink, or as directed by a healthcare professional. Alternatively, Thinkmist™ Prenatal may be ingested by spraying directly into the mouth.

Liquid in bottle

Very high concentration

Form not listed, but appears to be triglyceride

$0.33/spray

[$0.80]

$14.99/0.49 fl oz [14.6 ml] bottle (approx. 45 servings)

IFOS™ seal. igen™ non-GMO tested seal. Friend of the sea seal, NSF certified. Does not contain: Corn, dairy, egg, gluten, lactose, peanuts, shellfish, starch, sulfites, wheat, yeast, coloring or artificial flavors.

Precaution: Contains: Fish (sardine, anchovy, mackerel).

1 spray
Total Omega-3 Fatty Acids [EPA (Eicosapentaenoic Acid) 8.5 mg, DHA (Docosahexaenoic Acid) 200 mg, Other omega-3s 25.73 mg] 234.3 mg.

Ingredients: Fish oil, mixed tocopherols (vitamin E as an antioxidant), more...

APPROVED

Top Pick

for Prenatal DHA

Whole Foods Market Prenatal DHA

Dist. by Whole Foods Market

2 softgels

EPA: 205 mg ✔
DHA: 480 mg ✔
DPA^F: 111.5 mg
Total Omega-3: 830 mg ✔
Total Omega-7^F: 31.6 mg (59.1% palmitoleic acid)

Total Oil^F: 1,435.4 mg

Freshness: Pass

Heavy Metals: Pass

Take 2 softgels daily with food.

Medium/large softgel

Very high concentration

Triglyceride

$0.36/2 softgels

[$0.26]

$15.99/90 softgels

2 softgels

Vitamin D 10 mcg (400 IU)

IFOS™ seal.

Precaution: Contains Fish (Anchovy, Sardine, Mackerel) And Soy Ingredients. Produced In a Facility That Processes Peanuts, Tree Nuts, Milk, Eggs, Shellfish, Other Fish And Wheat.

2 softgels
Calories 10, Total Fat 1 g, Cholesterol 5 mg, Vitamin D (as cholecalciferol) 10 mcg (400 IU), Total Omega-3s (from purified fish oil) [Eicosapentaenoic Acid (EPA) 205 mg, Docosahexaenoic Acid (DHA) 480 mg, Other Omega-3s 145 mg] 830 mg.

Ingredients: Purified Fish Oil, Gelatin, more...

Children's Products:

APPROVEDⓘ

Top Pick

for Children

Barlean's Omega Pals - Chirpin' Slurpin' Lemonade Flavor

Dist. by Barleans.com

$ Price Check

1.5 tsp [7.5 ml]

EPA: 330 mg ✔
DHA: 210 mg ✔
DPA^F: 39 mg
Total Omega-3: 675 mg ✔
Total Omega-7^F: 215.4 mg (75.6% palmitoleic acid)

Total Oil: 2,000 mg

Freshness: Pass

Heavy Metals: Pass

1 1/2 tsp daily. Slurp from a spoon or mix into smoothies, yogurt, oatmeal and more.

Liquid in bottle

Moderate concentration

Form not listed, but appears to be triglyceride

Taste: Pleasantly sweet, lemony emulsion (i.e., a thick liquid)

$0.46/1.5 tsp

[$0.42]

$13.23/8 fl oz [227 ml] bottle (approx. 29 servings)

Non-GMO. Gluten Free. Sugar Free. Dairy Free.

1.5 tsp
Calories 30, Total Fat 2 g, Saturated Fat 0.5 g, Polyunsaturated Fat 1 g, Monounsaturated Fat 0 g, Cholesterol 15 mg, Total Carbohydrate 3 g, Total Sugars [Includes 0 g Added Sugars] 0 g, Sugar Alcohol 2g, Omega-3 Polyunsaturated Fat [Eicosapentaenoic Acid (EPA) 330 mg, Docosahexaenoic Acid (DHA) 210 mg, Other Omega-3 Fatty Acids 135 mg], more...

APPROVED

Oslomega® Kids Omega-3 Fish Oil

Dist. by Oslomega™

$ Price Check

1 softgel

EPA: 165 mg ✔
DHA: 110 mg ✔
DPA^F: 24.9 mg
Total Omega-3: 330 mg ✔
Total Omega-7^F: 15.6 mg (20.5% palmitoleic acid)

Total Oil^F: 592.1 mg

Freshness: Pass

Heavy Metals: Pass

For children 4 years and over, take 1 softgel daily with food.

Large (narrow) softgel

High concentration

Triglyceride

Taste: These are essentially medium softgels with a capsule that has a very slight and very mildly sweet strawberry flavor.

$0.20

[$0.36]

$10.00/60 softgels

Not manufactured with milk, eggs, shellfish, tree nuts, peanuts, wheat, or gluten.

Precaution: Contains: Fish (Anchovy, Sardine, Mackerel, Catfish, Tilapia) and Soy.

1 softgel
Calories 5, Total Fat 0.5 g, Cholesterol <5 mg, Total Omega-3s [EPA (Eicosatetraenoic Acid) 165 mg, DHA (Docosahexaenoic Acid) 110 mg, Additional Omega-3s 55 mg] 330 mg.

Ingredients: Highly Refined and Concentrated Omega-3 Fish Oil, more...

Pet Products:

NOT APPROVED

Doctors Foster + Smith Premium Plus® Omega-3 - For Dogs

Mfd. by 21st Century Animal HealthCare

1 chew

EPA: Claimed 180 mg; Found only 91.8 mg per chew (51% of listed amount)
DHA: Claimed 120 mg; Found only 53 mg per chew (44.2% of listed amount)
DPA^F: 12 mg
Total Omega-3^F: 182.1 mg
Total Omega-7^F: 118.2 mg (71.9% palmitoleic acid)

Total Oil: 1,296 mg

Freshness: NAⓘ

Heavy Metals: Pass

Give 1 chew daily per 20 pounds of body weight. For dogs 10 pounds or less, give 1/2 chew. If giving more than 1 chew, divide between morning and evening.

Large chew

Very low concentration

Form not listed

$0.25/chew

[$0.42 based on amount listed]
[$0.86 based on amount found]

$24.99/100 chews

Quality Seal NASC.

1 chew
Crude Fat 24%, Moisture (max) 16%, Eicosapentaenoic Acid (EPA, an Omega 3) 180 mg, Docosahexaenoic Acid (DHA, an Omega-3) 120 mg. Calorie Content (calculated): ME = 4,300 kcal/kg; 23.2 kcal/chew. 1 chew = 5.4 g.

Ingredients: Fish Oil, Glycerin, more...

APPROVED

Top Pick

for Dogs and Cats

Pet Honesty Wild Caught Omega-3 Fish Oil - For Dogs & Cats

Dist. by Pet Honesty

1 pump [2 ml]

EPA: 320 mg ✔
DHA: 210 mg ✔
DPA^F: 41.3 mg
Total Omega-3: 575.1 mg ✔
Total Omega-7^F: 176.5 mg (74.1% palmitoleic acid)

Total Oil: 639 mg

Freshness: Pass

Heavy Metals: Pass

0-15 lbs: 1/2 pump; 15-25 lbs: 1 pump; 25-50 lbs: 2 pumps; 50-75 lbs: 3 pumps; 75+ lbs: 4 pumps.

Liquid in bottle

Extremely high concentration

Form not listed, but appears to be triglyceride

$0.06/pump

[$0.06]

$29.99/32 fl oz [946 ml] bottle (approx. 473 servings)

None.

1 pump
Fat 99.5% min, Moisture 0.5% max, Total Omega Fatty Acids 35.5% min, Total Omega-3 Fatty Acids 30.0% min, EPA 18.0% min, DHA 12.0% min, Omega-6 Fatty Acids 7.0% min.

Ingredients: Wild caught anchovies, herring, mackerel and sardines.

Unless otherwise noted, information about the products listed above is based on the samples purchased by ConsumerLab.com (CL) for this Product Review. Manufacturers may change ingredients and label information at any time, so be sure to check labels carefully when evaluating the products you use or buy. If a product's ingredients differ from what is listed above, it may not necessarily be of the same quality as what was tested.

The information contained in this report is based on the compilation and review of information from product labeling and analytic testing. CL applies what it believes to be the most appropriate testing methods and standards. The information in this report does not reflect the opinion or recommendation of CL, its officers or employees. CL cannot assure the accuracy of information.

Copyright ConsumerLab.com, LLC, 2021 All rights reserved. Not to be reproduced, excerpted, or cited in any fashion without the express written permission of ConsumerLab.com LLC

ConsumerTips™:

What to Consider When Buying:
Getting EPA and DHA From Supplements:
When buying supplements containing EPA and/or DHA, keep in mind that products vary significantly in terms of the amounts and ratios of EPA and DHA. Be aware that only about a third of the total oil from fish is EPA and DHA, although this may be higher (up to about 85% as EPA and DHA) in a "concentrated" product". With a more concentrated product, one may be able to take fewer capsules of the same size. Your daily intake should be based on your reason for taking it (see below) and the amount that you are already getting from your diet.

The ratio of EPA to DHA in marine oils will also vary. Products made from menhaden and other small oily fish, for example, tend to have a ratio of EPA to DHA of 1.5:1 so that a capsule claiming 1 gram (1,000 mg) of fish oil, of which 30% is EPA and DHA, provides 180 mg of EPA and 120 mg of DHA. Salmon oil naturally contains more DHA than EPA (often several times more), and algal oil also typically contains more DHA than EPA. Does the ratio matter? It's not clear, but EPA may have slight benefits. A study of people with normal cholesterol levels found that both EPA-rich and DHA-rich fish oils at a very high daily dose of 12 grams (of which about 40% was EPA and/or DHA) for 8 weeks equally decreased triglyceride levels by about 14% but had little overall effect on LDL "bad" cholesterol or HDL "good" cholesterol. Both down-regulated several proteins, such as gelsolin, involved in inflammation, but fish oil rich in EPA did this to a greater extent than fish oil rich in DHA, suggesting a more anti-inflammatory effect of EPA. EPA also resulted in greater increases in ApoM (a subfraction of HDL), which has potential anti-atherosclerotic functions (Yang, Nutrients, 2020).

"Fishy" Labeling:
To distinguish themselves, some products sport terms which, in actuality, are meaningless and misleading:

· "Pharmaceutical grade" -- Although some products claim to be "pharmaceutical grade" this term means nothing, as the FDA has not defined what would constitute a pharmaceutical grade fish oil product.

· "Tested in FDA approved laboratories" -- The FDA does not approve analytical laboratories so these claims are not correct, although laboratories may be FDA registered and inspected. (None of the products in this Review make this statement.)

· "Krill Oil" -- Be aware that term "krill oil" in the name of a product does not necessarily means it's all krill oil. For example, in the past we found that if you looked carefully at the label of one krill oil product, the "Other Ingredients" section (which is in order of amount) showed "fish oil" first on the list. In fact, even the astaxanthin (naturally found in real krill oil, giving it its red color) has been added from an algal source, although this is not always disclosed on labels. (Fortunately, all of the products labeled as "krill oil" products in this review list only krill oil as the source of its omega-3 fatty acids).

· "Daily value for EPA and DHA" -- In the Supplement Facts panels of some products are claims that they provide a specific percentage of the DV (Daily Value) for EPA and DHA. DVs are developed by the USDA and FDA and relate to the recommended daily allowance of a required nutrient. However, no DV has been established for EPA and DHA. (None of the products in this review make this claim.)

Forms of Fish Oil — Natural Triglycerides, Ethyl Esters, Re-Esterified Triglycerides, or Monoglycerides: Is One Better?
The Forms:
The omega-3 fatty acids (EPA and DHA) in fish oil naturally occur in the form of triglycerides (fatty acids attached to glycerol). However, in most supplements, fish oil is not in this natural triglyceride form, but has been converted other forms in order to purify, concentrate, and/or stabilize it. Natural fish oil may also be purified and concentrated without solvents using methods such as supercritical CO2 extraction (which uses a gas and some heat) or winterization (which uses cold temperatures).

One of the most common forms of fish oil in supplements and medications is the ethyl ester form, which is created by exposing the fish oil to ethanol, replacing the glycerol molecule. This allows the fish oil to undergo molecular distillation: the oil is heated under high vacuum, causing certain other compounds, such as contaminants, to be removed while concentrating the omega-3 fatty acid ethyl esters. This distillation may also reduce levels of some potentially beneficial compounds (such as small amounts of vitamins) found in fish oil, but this has to be weighed against the benefit of removing contaminants and concentrating the EPA and DHA.

A third common form of fish oil on the market is known as re-esterified triglycerides. It is made by chemically converting ethyl esters back to triglycerides, so that most of the omega-3 fatty acids are, once again, triglycerides. A very small amount of ethanol (pure alcohol) is released from the ethyl ester form into the gut during this process (about 13% of EPA/DHA ethyl ester is ethanol), although the amount is likely to be insignificant (just a few drops of ethanol per softgel) for most people. (Note: It has been demonstrated, typically as part of a sales pitch, that the ethyl ester form of fish oil will dissolve Styrofoam — going through a cup, for example, in just a few minutes, while the triglyceride forms will not. While this effect is real — due to differences in the polarity of the forms — this is not a health concern).

Another marketed form of fish oil is the monoglyceride form, which is made by "predigesting" the triglyceride form of fish oil (Castejon, N Biotechnol 2020), although after you swallow any form of fish oil, your body's digestive enzymes free the omega-3 fatty acids so they can be absorbed.

Absorption:
While a sufficient dose of any of these forms can significantly raise the levels of EPA and DHA in your blood, a study found that people absorb more of these omega-3 fatty acids (about 76% more) from the re-esterified triglyceride form of fish oil than from the ethyl ester form (Dyerberg, PLEFA 2010). This study, in which each form was taken daily for two weeks (with the recommendation that it be taken at "meal times"), found that re-esterified triglyceride fish oil is absorbed even better than natural fish oil (34% more fatty acids are absorbed). Fish oil in a free fatty acid form was not absorbed as well as natural fish oil (about 14% lower absorption of EPA and DHA), although this difference was not statistically significant.

A study in 20 healthy people found that giving a single oral dose of 6,000 mg of the monoglyceride form of fish oil (MaxSimil 3020), providing 1,800 mg of EPA and 1,200 mg of DHA and given with a low-fat meal, resulted in double the blood level of DHA plus EPA than the same amount of fish oil in ethyl ester form over the following 24 hours, and about four times the level during the first 5 hours after eating (the critical period for absorption) (Chevalier, Eur J Clin Nutr 2020). The study was funded by a seller of MaxSimil, Neptune Wellness.

A subsequent study led by the same researcher (and also funded by Neptune Wellness) among 22 adults (average age 28) compared absorption of equal amounts of fish oil (880 mg of EPA and 332 mg of DHA) in monoglyceride (MaxSimil), ethyl ester, and triglyceride forms, all given with a low-fat meal. The study, over 24 hours, showed no difference in blood levels of DHA, although levels of EPA were twice and three times as high with the monoglyceride form compared to the triglyceride and ethyl ester forms, respectively (Chevalier, J Nutr 2021). Another study found that the absorption of fish oil in the monoglyceride form is similar to that of the free fatty acid form and similar to or slightly better than that of the triglyceride form when given to people following a low-fat diet (Cuenoud, Nutrients 2020).

It should be noted that none of the studies with the monoglyceride form were given with a high-fat meal, and studies that have expressly required fish oil to be taken with a high-fat meal have shown little difference in absorption among the various other forms (Nordoy, Am J Clin Nutr 1991; Lawson, Biochem Biophys Res Commun 1988).

Because the ethyl ester form has been the most widely available form on the market, most of the clinical studies with fish oil supplements have been conducted with this form, which have shown it to be generally safe, as well as effective for certain conditions such as improving cholesterol levels in people with high triglycerides (see What It Does).

An experiment in mice showed that DHA from natural fish oil relaxed smooth muscle in vascular tissue and temporarily lowered blood pressure, while DHA in the ethyl ester form did not. In fact, the ethyl ester form blocked natural DHA from having this blood pressure-lowering effect. Similar effects were found when comparing natural and ethyl ester forms of EPA (Hoshi, PNAS 2013). Although these findings might, at first, seem concerning, the doses were administered to the mice intravenously (IV), thereby allowing the ethyl esters into the blood; this could not happen if they had been taken by mouth, like a supplement. The findings, however, may raise issues for people who get fish oil as part of parenteral (IV) nutrition, as the ethyl ester and triglyceride forms may affect their blood pressure differently.

In summary, each of the four forms of fish oil, after being digested, will end up in the same form in your blood and, if taken with a fatty meal, will be equally well absorbed over 24 hours. However, if you are taking fish oil with just a small meal or no food, it may be fair to pay some premium for fish oil in the natural or re-esterified triglyceride forms. If you choose to use either of these two forms, look for products which list EPA and DHA as "triglycerides." Be aware that some products with "natural" in the name don't seem to provide truly natural fish oil, but may just start with natural fish oil which is then chemically treated or simply have "natural" as part of their brand name. Although the monoglyceride form of fish oil seems to have somewhat better absorption than the triglyceride form when fish oil is not taken with a high-fat meal, less is known about the safety and effectiveness of this form.

Also note that to avoid contaminants in an unrefined supplement, it's best to choose those made from small, oily fish that are low in food chain, such as anchovy, sardines or menhaden. Also be aware that fish "liver" oils can contain high levels of vitamins, such as vitamin A, which can be toxic at excessive doses (see Concerns and Cautions below for more information). Also see the separate Review of Vitamin A and Cod Liver Oil Supplements.

You'll find that many products also contain vitamin E or other antioxidants to stabilize the oils and prevent them from becoming rancid.

Algal and DHA-Rich Oil
Algae (including microalgae) are aquatic organisms which are sources of DHA and, to a lesser extent, EPA.

A recent analysis of clinical studies using relatively high dose DHA from algal oil (averaging 1,680 mg of DHA per day) found it to be similar to high dose EPA and DHA in lowering triglycerides and increasing HDL cholesterol (Bernstein, J Nutr 2011). The high-dose algal oil lowered triglycerides by about 15% and increased HDL cholesterol by about 5%. The algal oil also caused an 8% increase in LDL cholesterol. LDL cholesterol is often thought of as "bad" cholesterol; however, the LDL particles themselves became larger in size, which may make them less likely to harden arteries. Similar results have been seen with purified DHA from fish oil. DHA has also been found to be more effective than EPA at increasing HDL2 cholesterol the subfraction of HDL cholesterol that may be most protective against coronary heart disease (Mori, Am J Clin Nutr 2000).

If you are primarily interested in DHA or are vegetarian, algal oil supplements -- although more expensive than most fish oil supplements -- are a good option and they are typically very low in contaminants since algae is low on the food chain. The EPA and DHA in algal oil supplements is normally in the triglyceride form.

Krill Oil (and Astaxanthin)
Like fish oil, oil from krill (a shrimp-like crustacean) contains significant amounts of both EPA and DHA. Preliminary studies indicate that krill oil, like fish oil, has a beneficial effect on cholesterol and triglyceride levels and anti-inflammatory applications. The phospholipids in krill oil may enhance absorption of its EPA and DHA, and a 4-week study funded by a krill oil manufacturer (AkerBioMarine) showed that EPA and DHA from krill oil are absorbed at least as well, if not somewhat better, as they are from fish oil. The daily quantity of EPA provided in the krill and fish oil supplements were comparable; however, the amount of DHA present in the krill oil was approximately one half that provided in the fish. At the end of the treatment period, the mean plasma EPA concentration was 28% higher in the krill oil group compared with the fish oil group, whereas the DHA concentrations were comparable -- suggesting twice the absorption of DHA from the krill oil, although this was not evaluated for statistical significance (Maki, Nutr Res 2009).

Astaxanthin:
Krill oil also contains astaxanthin, a carotenoid is naturally produced by microalgae (Haematococcus pluvialis) which, through the food chain, provides the pink coloration of shrimp and other crustaceans, as well as salmon and trout. (A typical 4-ounce serving of farmed Atlantic salmon provides approximately 1 mg of astaxanthin and a similar serving of wild Pacific salmon provides about 4.5 mg.) Astaxanthin itself has a range of potential uses (see the Astaxanthin Supplements Review for more information), although all based on preliminary evidence. It may also be helpful in preventing sunburn.

ConsumerLab.com has found that some krill oil supplements contain additional astaxanthin — which may be naturally derived or synthetic, as this is often not disclosed on the label. Overall, there is currently not enough evidence to determine whether natural or synthetic astaxanthin provides any advantage over the other. Brands of natural astaxanthin derived from microalgae include BioAstin (Cyanotech), AstaREAL (Fuji Health Science) and AstaPure (Algatechnologies Ltd). In these products, astaxanthin exists in a single isomeric form (i.e., molecular configuration) known as 3S, 3S', which is the predominate form of astaxanthin naturally found in fish oil. Synthetic astaxanthin differs from natural astaxanthin in that it includes additional isomers, so that one quarter of synthetic astaxanthin is in the 3S, 3S' form. The other forms, however, are believed to be active anti-oxidants. Synthetic versions also provide astaxanthin in its "free form," while natural astaxanthin is in an "esterified" form; both forms can increase blood levels of astaxanthin in people. Although there is some very preliminary evidence that the free (synthetic) form of astaxanthin may be slightly more bioavailable (Coral-Hinostroza, Comp Biochem Physiol C Toxicol Pharmacol 2004), some in-vitro research that suggests the natural, esterified form may have more antioxidant activity (Capelli, Nutrafoods 2013). Synthetic astaxanthin appears to be safe in amounts typically used in foods and supplements -- one brand of synthetic astaxanthin, AstaSana (DSM) has been approved for use as a food additive.

Krill Harvesting: Krill is a primary food source for certain whales, seals, penguins and other animals. It's harvesting has been a subject of environmental debate. Proponents of the use of krill oil in supplements argue that it is plentiful and only a small percentage of total krill biomass is being harvested, most of which is used in fish meal and not for direct human consumption. There are also catch limits for sustainable exploitation established by a conservation commission known as CCAMLR, and registration and monitoring is required of harvesting vessels. However, other groups, such as the Antarctic Krill Conservation Project counter that krill harvesting may have detrimental effects on sea life and on other animals that depend directly or indirectly on krill, and that current limits and monitoring are insufficient.

Calamari Oil
Squid, also known as calamari (particularly when referring to it as a food) are a rich source of omega-3s. Unlike fish oil, calamari oil contains a higher amount of DHA than EPA (as you can see from the results table above). As squid have a short life cycle, they may be less likely to accumulate toxins than longer-lived fish, particularly those higher up on the food chain. A common source of calamari oil in supplements is trademarked Calamarine, which, according to the website of its manufacturer, Pharma Marine, is a socially responsible source of marine omega-3s as it is "produced solely from by-products of existing food production of calamari" and may be more eco-friendly than other animal sources based on how it is harvested.

Enteric-coated Pills:
Some fish oils come in enteric-coated pills, designed to release the oils in the intestine rather than the stomach -- to help avoid fishy aftertaste or fishy smelling burps. As long as these pills release on time, this should not compromise your absorption of omega-3s because oils are not absorbed in the stomach, but in the intestine. With the help of bile acids, oils get emulsified (made into smaller droplets) in the upper intestine so they can be more effectively acted on by pancreatic lipase (an enzyme) and absorbed further down the small intestine. If this doesn't happen, less oil may be absorbed.

So while enteric-coated pills may be fine, if you notice more oily stools, this would be an indication that the oils are not being well absorbed. Also, be aware that some of these enteric coatings are made with acrylics (such as methacrylic acid copolymer) that don't break down -- they are like thin latex balloons intended to pop open under specific conditions (they are also somewhat stiffer than regular softgels). You might find remains of these pills in your stool, but there is no reason to be concerned.

Getting EPA and DHA from Food:
You may want to consider getting omega-3 fatty acids directly from fish. For the general population, the American Heart Association (AHA) recommends at least two 3.5 oz servings of non-fried fish (preferably fatty fish) per week. For people with heart disease or cardiac risk factors, some experts recommend eating four 3-ounce servings of fatty fish per week. Fatty fish, such as the following, have higher levels of omega-3 fatty acids:

· Anchovies

· Bluefish

· Carp

· Catfish

· Halibut

· Herring

· Lake trout ^†

· Mackerel

· Pompano

· Salmon *

· Sardines

· Striped Sea Bass

· White Tuna (Albacore) **

· Whitefish

Source: U.S. Department of Agriculture, Agricultural Research Service. 2001; Oregon State University, Omega-3 Fatty Acid Content in Fish.
* Farmed salmon may contain more PCBs than other salmon.
** May contain an excessive amount of mercury.
^† Lake trout may be a good source of EPA and DHA (about 500 mg of EPA and 1,100 mg of DHA per 3.5 ounces), but many canned trout products contain rainbow trout, which contains only about 1/3 the amount of these omega-3 fatty acids (100 mg of EPA and 400 mg of DHA per 3.5 ounces).

Total amounts of omega-3s vary among fish. ConsumerLab.com's tests of canned tuna and canned salmon found some tuna to provide less than 100 mg of EPA and DHA per suggested serving (2 ounces), while others provided more. In general, canned salmon provided significantly more EPA and DHA than canned tuna (as salmon is a more oily fish) as well as lower concentrations of mercury and arsenic.

A three-ounce serving of canned salmon contains about 4.5 grams of fat of which 17% is EPA (166 mg) and DHA (587 mg). In salmon steaks and fillets, the fatty layer underneath the skin is richest in omega-3s. However, if you prefer not to eat this part, there is also a significant amount of DHA and EPA distributed throughout the flesh of the salmon, especially in the red muscle (located at the outside edges of a cut piece of salmon steak) and in the area surrounding the belly (this area is located in the outer portion of the "u" shape in a cut piece of salmon steak) (Aursand, J Sci Agr 2006).

Farmed vs. Wild Salmon — Which is Better? A question which has often been asked (and hotly debated) is whether farmed or wild salmon is better for you. The answer depends largely on what the farmed salmon is being fed, which can include fish oil and/or vegetable oil. Farmed salmon tends to contain more EPA and DHA per serving than wild salmon, as it is more fatty -- even though farmed has a lower percent of omega-3s as a percentage of total fat (Foran, J Nutr 2005). One review found that a 3.50 oz. (100 gram) serving of farmed salmon contained 2,650 mg of EPA + DHA, while the same amount of wild salmon contained much less, only 1,043 mg of EPA + DHA (Mozaffarian, JAMA 2006). Of course, these amounts will vary, particularly based on what farmed fish are fed. Data from fish tested in 2005/6 by the USDA found amounts to be closer: 1,900 mg (farmed) versus 1,410 mg (wild). A 2008 paper reported EPA + DHA in farmed salmon to be between 2,000 and 2,500 mg per 100 gram serving (somewhat larger than in the earlier studies) -- wild salmon was not included (Weaver, J Am Diet Assoc 2008). As supplies of fish oil have become tighter and demand for fish has grown, it has been noted that fish oil used to feed farmed fish is increasingly being replaced with vegetable oil. The effect of this is dramatically demonstrated by the drop in EPA + DHA per 100 grams of salmon farmed in Scotland from 2,740 mg down to 1,360 mg between 2006 and 2015, while, around the same time, the amount of fish oil fed to the salmon dropped by half and the amount of plant-based oils doubled (Sprague, Sci Reports, 2016).

Farmed salmon contains less vitamin D than wild salmon (240 IU of D3 per 100 gram serving, versus 988 IU, respectively) (Lu, J Steroid Biochem Mol Biol 2007). (It's worth noting that this study also found that almost all of the vitamin D was retained when the salmon was baked, but only half of the vitamin D remained when it was fried in vegetable oil.)

Unlike some other fish, such as tuna, both farmed and wild salmon are low in mercury. Salmon is also generally low in PCBs, although some farmed salmon has been found to be more contaminated than wild salmon. For example, the Mozaffarian study noted above found farmed salmon had about 7 times the amount of total PCBs as wild salmon. The farmed salmon had 21 ppb (parts per billion), or about 21,000 picograms per 100 gram serving, of total PCBs. However, as discussed further below, neither of these amounts is near the daily limit which the EPA considers potentially harmful. Levels of PCBs can vary depending on which country and region from which the salmon is sourced. A study of organically farmed salmon from Norway had significantly higher levels of PCBs than farmed salmon from the U.S. and Canada (Shaw, Environ Sci Technol 2006). Interestingly, levels of dioxin-like PCBs may be decreased when vegetable oil is substituted for fish oil in farmed fish feed (Nostbakken, Eviron Int 2015; Berntssen, Aquacult Nutr 2005), although this will also reduce levels of EPA and DHA.

(See Contaminants in Fish vs. Supplements for more about PCBs and mercury).

Farmed salmon tends to contain more omega-6 fatty acids per serving than wild salmon (approximately 0.56% vs. 0.2%, respectively), but amounts in both represent just a small fraction of the American Heart Association's guideline for daily omega-6 intake (5-10% of total dietary intake) (American Heart Association 2009). In fact, clinical trials have shown omega-6 PUFA intakes of between 11 and 21% of total dietary intake for up to eleven years reduce the risk of coronary heart disease without evidence of harm (Harris, Circulation 2009), so the somewhat higher amounts in farmed salmon should not be cause for concern. However, if you prefer wild salmon, it's interesting to note that sockeye salmon (a type of wild salmon) has been found to contain a high percentage of omega-3 fatty acids and a low percentage of omega-6 fatty acids, compared to farmed salmon (Weaver, J Am Diet Assoc 2008).

One study that compared the potential benefits from omega-3 intake with the risk posed by contamination (from PCBs, as well as other contaminants) between farmed and wild salmon concluded that wild Pacific salmon provided the best benefit-risk ratio compared to farmed salmon overall, but that farmed salmon from certain regions where contamination levels are relatively low, such as Chile and North America, provided a similar benefit-risk ration as wild Pacific salmon (Foran, J Nutr 2005).

Farmed salmon are commonly fed astaxanthin (and/or canthaxanthin), carotenoids that give wild salmon, as well as krill and shrimp their pink color. Wild salmon get astaxanthin in their diet from the algae and krill they consume. A typical 4-ounce serving of farmed Atlantic salmon provides approximately 1 mg of astaxanthin and a similar serving of wild Pacific salmon provides about 4.5 mg. Astaxanthin itself has a range of potential uses (see the Astaxanthin Supplements Review for more information), although all based on preliminary evidence.

The FDA has approved a genetically engineered salmon (AquAdvantage Salmon, AquaBounty Technologies, Inc.) as safe for consumption (FDA 2018). Sales were banned until labeling standards could be established but this ban was lifted on March 8, 2019. On the same day, AquAdvantage announced it would begin supplying its U.S. facility to grow its bioengineered salmon. The labeling standards require it to be labeled as "bioengineered food" or with a green symbol that includes the word "bioengineered" or, if part of multi-ingredient food, with the statement "contains a bioengineered food ingredient." The standard also states that for foods that are certified organic, "certification shall be considered sufficient to make a claim regarding the absence of bioengineering in the food." Companies have until January 1, 2022 to comply with this labeling. Bioengineered salmon will not have to be labeled as such when sold in restaurants or other food service establishments.

This bioengineered salmon provides similar amounts and ratios of total omega-3 and omega-6 fatty acids, as well as EPA and DHA, as non-genetically engineered farmed Atlantic salmon. Despite being genetically altered to grow about twice as fast as non-genetically engineered salmon, the company producing it reported no significant differences in levels of growth hormone, insulin-like growth factor-1 (IGF1), thyroid hormones T3 and T4, testosterone or estrogen.

In summary, farmed salmon (including genetically-engineered salmon) has tended to provide as much or more omega-3 fatty acids (including EPA and DHA) per gram than wild salmon because farmed salmon is a fattier fish than wild salmon, even though the oil in wild salmon has a higher ratio of omega-3 fatty acids to other types of fatty acids. As the amount of fish oil fed to farmed salmon declines (due to limited supply), the amount of EPA + DHA in farmed salmon is becoming more equivalent to that in wild salmon. Wild salmon, however, provides more vitamin D and astaxanthin than farmed salmon. Contamination levels are generally low in both types, but tend to be lower with wild salmon than farmed — although this and the nutritive qualities of farmed salmon largely depend on what it is fed.

Omega-3 Fortified Foods
Eggs fortified with DHA are also available in the U.S. and claim to contain about 150 mg of DHA in each egg. Chickens producing these eggs are typically fed algal DHA. Algal DHA is also an approved food ingredient, so that foods and beverages can be fortified with DHA and be considered vegetarian. Because some formula-fed infants may not be converting enough ALA to DHA, some formulas are also available with DHA -- which has been added to formulas for premature infants for many years.

Amounts of EPA and/or DHA in fortified foods and beverages tend to be about 50 to 100 mg per serving -- much lower than that found in a serving of fish or in a traditional fish oil supplement. While omega-3 fortified products can contribute to your intake of these fatty acids, they are typically not sufficient in themselves to provide the full generally recommended amounts of EPA or DHA.

Be aware that ConsumerLab.com found, in the past, that some fortified foods or beverages claimed to supply certain percentages of a "Daily Value" of EPA and DHA, stating the Daily Value for these to be 160 mg of EPA and DHA. Such statements are not correct. A "Daily Value" for omega-3 fatty acids has not been established. In April 2014, the FDA ruled that statements on the labels that claim a product is "high in" DHA or EPA (or statements using similar language, such as "rich in" or "excellent source of") are prohibited, as these types of statements are only permitted for nutrients for which reference levels have been established (FDA, Nutrient Content Claims: Final Rule 2014).

DPA: The "other" omega-3
After EPA and DHA, DPA (docosapentaenoic acid) is often the third most prevalent omega-3 fatty acid in fish oil -- although it often occurs in much smaller amounts and is typically not included in labels, yet some products contain over 100 mg per serving. ConsumerLab and other researchers have found DPA to represent about 2% to 5% of the total omega-3 fatty acids in fish oil (Byelashov, Lipid Technol 2015). However, much larger amounts of DPA can be obtained from eating a 3.5 oz. portion of the following fish: raw salmon (393 mg) Atlantic mackerel, (200 mg), and Pacific herring, bluefin tuna, and rainbow trout (between 100 mg and 200 mg) (Byelashov, Lipid Technol 2015). Similarly high amounts can be obtained from canned salmon, particularly sockeye (red) salmon, while canned tuna tends to contain smaller amounts (as well as lower overall amounts of omega-3 fatty acids) (see ConsumerLab's Canned Tuna and Salmon Review).

In the body, DPA can be produced from EPA, and structurally, the two fatty acids are very similar (Dyall, Front Aging Neurosci 2015). Higher blood levels of DPA have been associated with lower blood triglycerides, cholesterol and inflammation, and a lower risk of heart attack and overall risk of coronary heart diseases (Byelashov, Lipid Technol 2015). Having higher blood levels of EPA and DPA, but not DHA, has been associated with healthier aging (longer life free from major cardiovascular, lung and kidney disease, cancer, physical or mental dysfunction). A 13-year-study of over 2,500 older men and women (with an average age of 74 at the start of the study) found that having the highest blood levels of EPA and DPA, as opposed to the lowest levels, was associated, respectively, with a 24% and 18% lower risk of unhealthy aging. No such association was found with blood levels of DHA (Lai, BMJ 2018).

However, there are very few clinical studies on the effects of DPA supplementation. A preliminary study in Australia among ten healthy young women found that DPA supplementation (2 grams of 99.8% pure DPA taken for one day, followed by 1 gram per day for six days) significantly increased blood levels of DPA, as well as EPA plus DHA, and the researchers proposed that DPA may act as a "reservoir" for EPA and DHA for the body to use as-needed (Miller, Eur J Nutr 2013). A small, company-funded study among men and women with moderate to high triglyceride levels found that 4 grams of a prescription DPA/EPA formula (MAT9001, Matinas BioPharma) taken for two weeks lowered triglyceride levels by about 13% more, and lowered very low density lipoprotein (VLDL) by 24% more than the same dose of a prescription ethyl ester EPA (Vascepa, Amerin). However, the exact amount of DPA in the product is not known, and the product does not appear to be on the market.

Contaminants in Fish vs. Supplements
Mercury:
Mercury is not a known contaminant in fish oil or other marine oil supplements. ConsumerLab.com has never found mercury in such supplements. Mercury is a potential problem, however, in fish meat. Levels of pollutants, such as mercury, tend to be higher in long-lived, larger fish, particularly shark, swordfish, king mackerel, and tilefish. These fish tend to average about 1,000 ppb (parts per billion) of mercury -- the FDA limit for human consumption -- while most other fish tend to have about one-tenth to one-third of this amount. Eating a fish with 1,000 ppb of mercury is not necessarily toxic, but it should not be consumed by young children and pregnant or nursing women, or by anyone on a regular basis. The Environmental Protection Agency (EPA) has also advised that fresh-water fish may contain more mercury than commercially caught fish and advises that "If you are pregnant or could become pregnant, are nursing a baby, or feeding a young child, limit consumption of fish caught by family and friends to one meal (about 6 ounces) of fish per week." The same limit is recommended for albacore ("white") tuna, as it may occasionally contain excessive levels of mercury.

PCBs: PCBs occur in nearly all fish oil supplements but almost always at extremely low levels, as shown in our testing. You are likely to get a much higher amount of PCBs from eating fish. A study of fish sold in markets in Germany, for example, looked at a dioxin-like PCBs (dl-PCBs) which are a small subset of PCBs but which are known to be most toxic. It found that oily fish (such as salmon) to contain about 2 picograms of dioxin-like PCBs (dl-PCBs) per gram (Karl, J Verbr Lebensm 2008). A small serving (3 ounces or 85 grams) of salmon, therefore, would contain about 170 picograms of dl-PCBs. Even a serving of less oily fish (which tend to have fewer PCBs but also less omega-3s) is likely to contain several times more PCBs than a typical fish oil supplement.

The FDA permits a 3-ounce serving of fish to contain about 169,000,000 picograms of total PCBs, 1,000 times more than in any of the products in this review. The EPA, using a more conservative approach, estimates that the average adult can consume 1,400,000 picograms of total PCBs per day without harmful effects. If you are concerned about mercury and other potential contaminants, concentrated fish oil products may be a better choice, provided that they contain the claimed amount of oils and meet other quality parameters tested for in this review.

Omega-3 vs. Omega-6 Fatty Acids:
Some experts suggest that the American diet contains too little omega-3 fatty acids and too much of another essential fatty acid family called the omega-6 fatty acids. Omega-6s are found in oils from corn, sunflower, soy, peanut and other plants. The typical ratio of omega-6's to omega-3's in the American diet is believed to be as high as 14:1 (14 grams of omega 6's for every gram of omega-3's); these experts suggest that a ratio of no more than 3:1 (3 grams of omega-6's for every 1 gram of omega-3) may be preferable. However, the evidence for this recommendation is sketchy at best.

Omega-7 Fatty Acids:
Omega-7s are a class of unsaturated fatty acids including palmitoleic acid, vaccenic acid and margaroleic acid. Palmitoleic acid is one the most commonly occurring omega-7s, found in foods like eggs, salmon, anchovy, sardines, macadamia nuts, olive oil and cod liver oil. It is also synthesized in the body by the liver and found in fat tissue. As noted earlier, some fish and marine oil supplements may also contain palmitoleic acid, although amounts are typically not listed on the label and, in general, it appears that the more highly concentrated a fish oil is in EPA and/or DHA, the lower the concentration of omega-7 fatty acids will be. Products made from algae oil contain virtually no omega-7s, although it is abundant in the sea buckthorn. (See the 2nd column of the Results Table for amounts of total omega-7s and the percentage of palmitoleic acid found in each product.)

Unfortunately, clinical studies have failed to show cardiovascular benefit with omega-7 fatty acids and palmitoleic acid. A study that reported benefits on lipid levels with daily supplementation with 220 mg of palmitoleic acid daily for 30 days was later retracted due to concerns over its statistical accuracy (Bernstein, J Clin Lipid 2014).

In a study among 50 men and women with chronic musculoskeletal discomfort and slightly elevated levels of c-reactive protein (CRP, a blood marker of inflammation in the body sometimes also used to assess cardiovascular risk), 688 mg of palmitoleate from an omega-7 fish oil blend (Barlean's) taken daily for three weeks did not reduce levels of CRP or other blood markers of inflammation, or decrease muscle discomfort or improve self-reported quality of life compared to placebo (medium-chain triglycerides, i.e., MCT oil) (Sasagawa, Nutrients 2021).

Palmitoleic acid should not be confused with palmitic acid, a saturated fatty acid found in many of the same foods as palmitoleic acid. Palmitic acid slightly increases both LDL and HDL cholesterol, so its effect on the LDL/HDL ratio is considered to be neutral, and in general, it does not seem to pose an increased risk of cardiovascular disease (Fattore, Int J Food Sci Nutr 2013). However, some people with very high cholesterol levels may want to avoid palmitic acid when possible.

A branded, "purified" form of palmitoleic acid found in a number of omega-7 supplements, called Provinal® (Tersus Pharmaceuticals) is processed to reduce the amount of palmitic acid it contains to less than 1%. Provinal® is derived from anchovy and contains 50% palmitoleic acid (most of the omega-3 fatty acids have also been removed). Many of the supplements on the market containing this brand provide the omega-7 oil in a softgel or capsule containing 460 mg of Provinal® (210 mg of palmitoleic acid) each, and cost between $14 and $25 dollars for 30 pills (a one-month supply).

Clinical studies assessing cardiovascular and other potential effects of sea buckthorn berry juice or puree have failed to show a benefit.

One small clinical study found 300 mL (about 10 ounces) of sea buckthorn juice (pressed from whole berries) daily for 8 weeks did not significantly lower total cholesterol, LDL cholesterol or reduce platelet aggregation in healthy men (average age 35), although there was a non-significant increase in HDL and triglycerides (Eccleston, J Nutr Biochem 2002).

A study in China among 99 people with high cholesterol who were not taking cholesterol-lowering medication found that taking 30 grams (about 1 ounce) of de-seeded sea buckthorn berry puree three times daily for 90 days did not improve total cholesterol, LDL cholesterol, HDL cholesterol or triglycerides, nor did it improve blood pressure, body mass index or biomarkers of atherosclerosis and inflammation, compared to placebo (Zhou, Anim Biotechnol 2020).

A puree made from frozen sea buckthorn berry, has been tried in healthy men and women to try to prevent colds. It did not have that effect, although it did decrease levels of the inflammatory marker CRP compared to placebo (Larmo, Eur J Clin 2008).

Be aware that sea buckthorn seed oil is very different than the juice and has only about 1/10th the concentration of omega-7 fatty acids.

Also, be aware that some supplements containing omega-3 and omega-7 fatty acids are marketed as omega-10 fatty acids — claiming provide a "more complete" fatty acid formula (i.e., omega-3 plus omega-7) for cardiovascular health. However, as noted above, there is no evidence to support this, there is no "omega-10" fatty acid, and many fish oil supplements already do contain omega-7 fatty acids. What to Consider When Using:
Dosage:

· In the U.S., there is no official recommended intake for EPA and DHA in healthy people (See Daily Value for more information). However, some other countries recommend from 300 mg to 500 mg per day of a combination of EPA and DHA. This is roughly equivalent, if not greater than, the amount of omega-3s obtained from two servings of fish per week, as suggested by the American Heart Association (See Getting EPA and DHA from Food).

· The most recent evidence does not support fish oil supplementation for reducing heart attacks and strokes (Kwak, Arch Intern Med 2012). Any potential cardiovascular benefit of supplementation may be limited to people who do not regularly consume fish in their diets and who are not taking other medications for heart disease. A diet high in fatty fish (2 servings of marine fish per week) continues to be recommended as it provides omega-3 fatty acids and replaces less healthful protein sources, such as red meat (Hu, Arch Intern Med 2012). A study in Norway among CAD patients showed only those with intakes lower than 300 mg per day of omega-3 fatty acids had a slightly increased risk of coronary events. There was no significant difference in risk among groups with high (580 mg), very high (1,360 mg) or even extremely high (2,640 mg) daily intakes of omega-3's (Manger, Am J Clin Nutr 2010).

· A typical dose of fish oil for specific therapeutic uses is 6-12 grams daily. However, as noted above, EPA and DHA represent only part of the total oil in fish and their levels vary among products. For most therapeutic uses of omega-3s, the daily dosage of total EPA and DHA tested in studies has ranged from 1-6 grams daily. Higher dosages have been tried by some researchers, especially for the treatment of schizophrenia, Raynaud's phenomenon, and lupus.

· For maintaining remission in ulcerative colitis, 1,000 mg twice daily of EPA in enteric-coated capsules (Scaioli, Clin Gastro Hep 2018).

· For pregnant and nursing women, the recommended dose of DHA, from either supplements or fish, is 100 to 200 mg per day. 400 mg DHA daily has been shown to reduce colds during initial months of infancy among women with otherwise low DHA intake (Imhoff-Kunsch, Pediatrics 2011). A study using higher amounts of omega-3's (800 mg DHA and 100 mg EPA daily) showed reduced risk of very premature birth as well as lower risk of egg allergy in infants (Makrides, JAMA 2010, Palmer, BMJ 2012). Even higher amounts (1,320 mg EPA and 880 mg DHA) have been shown to reduce the risk of persistent wheezing and asthma in offspring when taken starting at 24 weeks of pregnancy (Bisgaard, NEJM 2016).

· For potentially reducing the risk of developing of retinal disease, eating fish providing approximately 200 mg or more of EPA and DHA per day may be helpful. This is based on the dietary intakes of participants in the AREDS study who had the lowest incidence of retinal disease. A separate study suggests benefit with consumption of at least one serving of fish per week, particularly canned tuna or dark-meat fish (salmon e.g., mackerel, salmon, sardines, bluefish, and swordfish), which works out to consumption from the diet of about 100 mg of EPA and 230 mg of DHA per day (Christen, Arch Opthamol 2011). However, as noted in the Eye Disease section above, fish oil supplementation has not been found to reduce the risk or progression of age-related macular degeneration.

· For treating symptoms of dry eye, a combination of fish oil (126 mg EPA and 99 mg DHA) in a formula with black currant seed oil, vitamins A, B6, C, and E, magnesium sold as HydroEye been successfully used (Sheppard, Corna 2013). A large study of young adults found that taking a fish oil capsule twice daily (each capsule providing 180 mg EPA and 120 mg DHA) improved symptoms of dry eye associated with computer use (Bhargava, Contact Lens & Ant Eye 2015).

· For maintaining weight during initial chemotherapy, fish oil providing 2.2 grams of EPA per day (Murphy, Cancer 2011). (Note: Despite this apparent benefit, fish oil maybe contraindicated during chemo, as explained in the Concerns and Cautions section).

· For depression, 2,500 mg (consisting of 1,670 mg EPA and 830 mg DHA) taken once daily for eight weeks (Rondanelli, J Am Col Nutr 2010). In mildly cognitively impaired individuals, combinations providing either 1,550 mg DHA with 400 mg EPA or 1,670 EPA with 160 mg DHA have also shown benefit over 6 months (Sinn, Br J Nutr 2011). Also, 1,000 mg per day of EPA together with the prescription drug fluoxetine (Prozac) appears to be more effective than either EPA or fluoxetine alone. A daily dose of 1,000 mg EPA in people with depression who were taking a standard antidepressant medication was also shown to result in a significantly better outcome compared to placebo (Peet, Arch Gen Psychiatry 2002). In the study, this dose was more effective than higher doses of EPA.

· For anxiety, 2,496 mg (providing 2,085 mg EPA and 348 mg DHA), taken once daily (Kiecolt-Glaser, Brain Behav Immun 2011).

· For stress, 9 grams (providing 1,600 mg EPA and 1,100 mg DHA), taken once daily (Carter, Am J Physiol 2013).

· For migraine headache, 400 mg EPA and 350 mg DHA taken twice daily along with medication (amitriptyline - 10 mg) (Soares, Nutr Neurosci 2017).

· For epilepsy, 1,080 mg EPA plus DHA taken daily for 10 weeks has been shown to reduce the frequency of seizures (DeGiorgio, J Neurol Neurosurg Psychiatry 2014).

· For improving attention in boys with ADHD, 650 mg of EPA and 650 mg of DHA daily (Bos, Neuropsychopharm 2015)-- but not in children already getting these omega-3's from diets (Chang, Translational Psych 2019).

· For improvement in working memory in healthy, young adults, 2,000 mg of fish oil (providing 930 mg EPA and 750 mg DHA) daily (Narendran, PLoS One 2012) or 2,250 mg of fish oil (providing 1,160 mg of DHA and 170 mg EPA) (Stonehouse, Am J Clin Nutr 2013). Best results may take 6-months — the period required for DHA levels in tissue to plateau. In healthy older adults, executive functioning improved with 4 fish oil capsules daily, each containing 1,000 mg of fish oil (300 mg EPA and 220 mg DHA) (Witte, Cereb Cortex 2013).

· For Alzheimer's disease, taking 2 fish oil capsules each morning (each containing 1 gram of fish oil, providing 325 mg EPA and 225 mg DHA in the triglyceride form) and another capsule with lunch, slowed the decline in subjects' abilities to perform daily activities. Adding 600 mg of alpha-lipoic acid in the morning slowed the decline in the subjects' cognitive functioning. (Shinto, J Alzheimers Dis 2014).

· For strength training, 1,000 mg of fish oil (providing 180 mg EPA and 120 mg DHA) twice daily (Rodacki, Am J Clin Nutr 2012). For increasing muscle and strength in older people, 4,000 mg of extremely concentrated fish oil (providing 1,860 mg of EPA and 1,500 mg of DHA daily) (Smith, AJCN 2015).

· For acne, 1,000 mg EPA and 1,000 mg DHA taken daily reduces the number and severity of lesions (Jung Acta Derm Venereol 2014).

· For periodontitis, 2,000 mg per day of DHA (from four capsules of algal oil which was 53.6% DHA) along with low-dose aspirin (81 mg per day) has shown improved outcomes (Naqvi, J Dent Res 2014).

Prescription Fish Oil vs. Supplements
For people with high triglycerides who have not responded well to other treatments, the American Heart Association (AHA) has stated that prescription n-3 FAs (EPA + DHA or EPA-only) at a dose of 4 g/d (>3 g/d total EPA + DHA) are an effective and safe option for reducing triglycerides as monotherapy or as an adjunct to other lipid-lowering agents (Skulas-Ray, Circulation 2019). The AHA notes that omega-3 fatty acids with EPA + DHA or with EPA only appear roughly comparable for triglyceride lowering and do not increase low-density lipoprotein cholesterol when used as monotherapy or in combination with a statin. (Prior to the FDA approving specific fish oil products as drugs, earlier recommendations from the AHA had referred to "fish oil capsules" rather than prescription products.) Due to the large dose of omega-3s required, fish oil products highly concentrated in omega-3s are used, as these can reduce the total amount of oil needed by about two-thirds compared to unconcentrated fish oil.

A prescription fish oil, Lovaza (previously known as Omacor and still sold under that name in other countries), provides 840 mg of EPA and DHA per 1-gram capsule (an 84% concentration), of which approximately 465 mg is EPA and 375 mg is DHA. A generic version of Lovaza is also available at lower cost. It is sold by Teva Pharmaceuticals as 1-gram capsules of "omega-3-acid ethyl esters" and was approved by the FDA as providing approximately the same amounts of EPA and DHA in the same chemical form as Lovaza. Another prescription fish oil, Epanova (AstraZeneca), which has been approved by the FDA but is not yet marketed, contains a similar concentration of fatty acids per 1 gram capsule (85%) but slightly more EPA (500 — 600 mg) and slightly less DHA (150 to 250 mg) — provided in a "free fatty acid form" rather than the ethyl ester form found in Lovaza. Both of these prescription fish oils have been approved by the FDA to reduce triglyceride levels in adults with severe hypertriglyceridaemia (triglyceride levels greater than or equal to 500 mg/dL), in conjunction with a low-fat diet. Lovaza and Epanova have also both been shown to help lower triglyceride levels in people taking statin drugs. 

It may be possible to significantly lower triglyceride levels with a lower dose (and fewer pills) of Epanova than Lovaza. While Lovaza has been shown in clinical studies to lower triglyceride levels by 20 - 30% and has been approved for use at a dose of four 1-gram capsules per day (Koski, PT 2008), Epanova has been shown in clinical studies to significantly lower triglyceride levels and has been approved for use at the same dose -- as well as a lower dose of two 1-gram capsules per day (Kastelein, J Clin Lipidol 2014). Epanova lowered triglyceride levels by 30% at the 4-gram daily dose, and by 26% at the 2-gram daily dose.

Another difference between Epanova and Lovaza may be the way they are absorbed. While Lovaza contains fatty acids in the ethyl ester form (the form found in most fish oil supplements), the fatty acids in Epanova are in a "free fatty acid" form. The maker of Epanova claims that this form is more bioavailable than the ethyl ester form because it does not have to be broken down by enzymes before it is absorbed, and therefore does not need to be taken with food or a high-fat meal. (See the discussion on the different forms of fish oil for more information).

A clinical study comparing Epanova and Lovaza (funded by the makers of Epanova) found Epanova significantly raised levels of DHA and EPA, and lowered triglyceride levels, compared to Lovaza (Offman, Vasc Health Risk Manag 2013). In the study, 52 healthy men and women were instructed to follow a low-fat diet, and were given either four 1-gram capsules of either Epanova or Lovaza once daily, 30 minutes prior to a low-fat breakfast, for two weeks. Blood levels of EPA and DHA were 3 and 4 times higher, respectively, and triglyceride levels were reduced by 13% more, in those taking Epanova.

The most commonly reported side-effects for Epanova are diarrhea, nausea and abdominal pain, while those for Lovaza include burping, upset stomach and a change in the sense of taste (AstraZeneca, Epanova Prescribing Information; Koski, PT 2008). Both have the potential to increase LDL cholesterol or levels of certain liver enzymes in some people (see Concerns and Cautions).

A third fish oil supplement available by prescription,

Vascepa (Amarin), contains a 96% concentration of the ethyl ester form of EPA - but no DHA — and has been shown in clinical studies to significantly reduce triglyceride levels without increasing LDL cholesterol levels. Like Lovaza and Epanova, Vascepa has been approved for use in conjunction with a low-fat diet to reduce triglyceride levels in adults with hypertriglyceridemia. The recommended daily dose of 4 grams (taken as 2 capsules twice daily with food) has been shown to decrease triglyceride levels by 21- 33% over three months with no significant change in LDL cholesterol levels (Nelson, Ann Pharmacother 2013). Interestingly, the most commonly reported side effects were not the gastrointestinal issues reported with use of Lovaza and Epanova, but joint and throat pain (Amarin, Vascepa Prescribing Information).

In a study that ran for nearly 5 years, Vascepa (4 grams per day) demonstrated a 25% reduction in the risk of first-time heart attack, stroke or other major cardiac event among statin-treated adults with persistently elevated triglycerides (150 to 499 mg/dL) and other cardiovascular risk factors. The proportion of adverse events was similar between those treated with Vascepa and placebo, although there was increase in cases of atrial fibrillation or flutter (3.1% vs. 2.1% for placebo) (Bhatt, NEJM 2018). A second analysis of the same study that also took into account second, third and any additional cardiovascular events during the same 5-year time period found an even greater decrease in risk (30%) of events compared to placebo (Bhatt, J Am Coll Cardiol 2019). However, as discussed below, questions have been raised as to whether the placebo used in this trial (mineral oil) may have affected the results.

In a separate study, 4 grams per day of Vascepa or placebo taken for 18 months by 80 people with elevated triglyceride levels (despite statin treatment) and atherosclerosis showed that Vascepa reduced coronary atherosclerosis progression, in terms of total plaque, by 9% versus an 11% increase among those given placebo. Even more notable was a 17% decrease in "low-attenuation" plaque (a strong predictor of heart attack) versus a 109% increase with placebo (Budoff, Eur Heart J 2020). Vascepa was initially approved for treating patients with very high (severe) triglyceride levels (over 500 mg/dL) and this was extended in December 2019 to include its use as an adjunctive therapy (i.e., in addition to statins) to reduce the risk of cardiovascular events among adults with elevated triglyceride levels of 150 mg/dL or higher who also have either established cardiovascular disease or diabetes and two or more additional risk factors for cardiovascular disease. Patients are advised to continue physical activity and maintain a healthy diet when using Vascepa.

[Note: A clinical trial of Epanova (highly concentrated, free-form, EPA/DHA) was undertaken to determine whether it could, similar to Vascepa, reduce the risk of cardiovascular events in statin-treated adults with moderately high triglyceride levels (175 - 499 mg/dL) and low levels of "good" HDL cholesterol. However, in January 2020, the maker of Epanova announced it would halt the study due to its "low likelihood of demonstrating a benefit." Publication of the results in November 2020 showed that although Epanova (4 grams per day) reduced triglyceride levels by 19% (versus 0.9% with corn oil as a placebo) and modestly decreased a measure of inflammation (c-reactive protein), there was no reduction in cardiovascular events, and, concerningly, it increased the risk of atrial fibrillation (2.2% vs. 1.3% for placebo). Epanova also caused more gastrointestinal complaints (24.7% vs. 14.7%) (Nicholls, JAMA 2020).]

One theory as to why Vascepa showed a benefit but Epanova did not is that Vascepa raised EPA levels more than Epanova. However, an analysis showed that those who achieved the highest levels of EPA with Epanova (which was higher than the average reported with Vascepa) had no benefit. Perhaps a more plausible explanation is that the placebo used in the Vascepa trial (mineral oil) may have had adverse cardiovascular effects, thus making Vascepa look better than it was. In fact, researchers who compared the results of the Epanova and Vascepa trials with data modeled on the general population proposed that approximately half of the estimated benefit found with Vascepa versus Epanova might be due to the negative effects of mineral oil on triglyceride levels, LDL cholesterol, and C-reactive protein (CRP) (Doi, Eur Heart J 2021). The placebo used in the Epanova study (corn oil) is not believed to cause negative cardiovascular effects. More research is needed to understand these differences (Nissen, JAMA Cardiol 2021).

The annual cost of Vascepa is approximately $3,000. Fish oil supplements tend to be less expensive than prescription fish oil capsules. Similarly high concentrations of EPA and DHA can be found among dietary supplements at lower cost (see Softgels Compared to Prescription Omega-3s).

A krill-based omega-3 product (CaPre, Acasti Pharma) is also under development as a prescription product. It contains about half the concentration of EPA and DHA as the prescription fish oils in "a combination of phospholipid esters and free fatty acids." However, a clinical trial among adults with severe high triglyceride levels (500 mg/dL to 1500 mg/dL), including individuals on statin therapy, found that it was not significantly better than placebo, although, strangely, both it and the placebo groups experienced substantial decreases in triglyceride levels (-36.7% with CaPre vs. -28% with placebo).

How to Take:
Taking fish oil with fatty meals helps increase its absorption (Dyerberg, PLEFA 2010). Fish oils are also best tolerated when taken with meals, and, if possible, should be taken in divided doses, i.e., divide the dose in half and take twice daily, or in thirds and take three times a day.

The reason why fish oil is better absorbed with a fatty (or oily) meal is that fats trigger the release of bile into the small intestine and this causes the oil to be emulsified (broken into smaller droplets), making absorption easier. Some fish oil is sold in an emulsified form, such as Coromega. If you only take fish oil without food, you may absorb somewhat more if you use an emulsified product, although they tend to cost more than regular fish oil. On the other hand, if you tend to take fish oil with meals that contain reasonable amounts of fats or oils, the fish oil will likely be absorbed just as well regardless of whether it's emulsified or regular fish oil.

Interestingly, a study that compared taking Coromega liquid to regular fish oil from a capsule found that the EPA from Coromega was absorbed almost twice as well as the EPA from the capsule. However, overall, the total amount of EPA and DHA was not absorbed significantly better from Coromega (Raatz, Lipids 2016). Furthermore, the fish oils were taken along with a low-fat breakfast and it's possible that any comparative benefit of Coromega would have disappeared if the fish oils had, instead, been taken with fatty meal.

A "self-emulsifying" fish oil is also sold as Nature Made Omega-3 with Xtra Absorb Technology. A study in which it was given without any food showed it to have 8.2-fold higher bioavailability for EPA + DHA than a non-emulsified fish oil (the prescription fish oil Lovaza), particularly for EPA (18.3-fold higher), while DHA was 4.5-fold higher. Both products contained EPA and DHA in the ethyl ester form, as this permits greater concentration than the natural triglyceride form (Maki, Clin Therapeutics 2018). However, as with the Coromega study, had the fish oils been taken with food, there may have been little or no difference in bioavailability.

Keep It Fresh:
Omega-3 fatty acids can spoil, so it is best to keep products out of heat and light. Once opened, tightly reseal the container. If possible, refrigeration can help prolong freshness and is particularly important with bottled liquids. A slight cloudy appearance of the oil is normal after refrigeration -- just shake the bottle before use. If you use a bottled liquid, purchase a size that you will completely use within a few weeks because once air is introduced into the bottle, spoilage may begin. As noted earlier, all products in this review were tested for freshness unless deeply colored (such as krill oil) or containing flavorings, as these characteristics can prevent accurate testing.

If you won't be using a portion of the product soon, you can also freeze fish oil. This will extend its freshness and not have an adverse effect on the oil (and this generally will not affect capsules, either).

Some products contain added antioxidant ingredients, such vitamin E, rosemary or ascorbic acid, which can help keep fish and marine oil fresh.

Concerns and Cautions:

While fish oil supplements are generally considered safe, there are a few caveats and cautions you should take into consideration before you buy. While krill oil has not been as extensively studied as fish oil, it is reasonable to assume that the same concerns and cautions apply.

· The most common side effects are fishy smelling burps and diarrhea. Fish oil and krill oil have been found to have similar side effects, such as nausea, gas, bloating and diarrhea, although one study reported that gas and bloating were more frequent with krill oil supplementation than with fish oil supplementation (Maki, Nutr Res 2009).

· Up to about 20 grams of fish oil can be well tolerated by most adults. However, such high amounts may not be beneficial, and the FDA recommends that consumers not exceed more than a total of 3 grams per day of EPA and DHA omega-3 fatty acids, with no more than 2 grams per day from a dietary supplement. Such high doses may suppress the immune system. Unless medically necessary, such doses should be avoided, particularly by immunocompromised individuals. The potential for immune suppression was highlighted in a review of several studies in animals which found very high amounts of EPA and DHA to dampen immunity, resulting in reduced survival from bacterial, viral and fungal infections (Fenton, Prostag Leukotri EFAs 2013). These adverse effects occurred when EPA & DHA consumption contributed as much as 1% to 10% of an animal's total daily energy intake. In terms of human consumption, this would be about 2,200 mg to 22,000 mg of EPA and DHA daily, which is much higher than provided by most fish oil supplements (typically around 500 mg daily), although the dosage taken to lower triglycerides would fall in the lower end of this range. Commenting on these findings, a researcher noted, "Our main concern here is the hyper-supplemented individual, who may be taking high dose omega-3 supplements and eating four to five omega-3 enriched foods per day." (OSU website, 2013).

· Be aware that cod or other fish liver oils are not always a good substitute for fish oil supplements as these may be high in vitamins A and D. Because these vitamins can be toxic, make sure that you do not exceed safe levels (see Multivitamin Product Review for Tolerable Upper Intake Levels (ULs) for vitamins and minerals).

· Fish oil may have a blood-thinning effect, especially at doses above 3 grams of EPA + DHA per day (Zucker, Atherosclerosis 1998). Lower doses (less than 1 gram of omega-3 fatty acids, including EPA + DHA, per day) do not appear to have this effect (Bays, Am J Cardio 2007). However, as a precaution, fish oil should be used only under a physician's care by people with bleeding disorders such as hemophilia, and those taking strong prescription blood thinners, such as warfarin (Coumadin), heparin or apixaban (Eliquis). Among people on warfarin, clotting time (INR) has been shown to increase upon beginning or increasing fish oil supplementation among people on warfarin, returning to normal after discontinuing fish oil. However, there are cases among older people on warfarin and fish oil who have suffered traumatic injuries and clotting time could not be adequately reduced. In one case, an 87-year old man with head trauma due to a motor vehicle collision died from uncontrollable bleeding into his brain despite the use of treatments (prothrombin and vitamin K) which normally reverse the effects of warfarin (Gross, J Trauma Nursing 2017).

· Although patients are often advised to stop taking fish oil several weeks before surgery, a large study of over 1,500 men and women who underwent cardiac surgery (such as coronary artery bypass or valve surgery) found that taking 8 to 10 grams of the prescription fish oil Lovaza two to five days before surgery, and 2 grams per day after surgery until discharge or up to ten days, did not increase bleeding during or after surgery compared to placebo. In fact, those who took the fish oil were less likely to need a blood transfusion, and those with higher blood levels of omega-3s had a lower risk of bleeding compared to those with lower blood levels (Akintoye, Circ Cardiovasc Qual Outcomes 2018).

· High-dose fish oil supplementation may also increase the risk of bleeding in the eye. A 32-year old Chinese man with extreme nearsightedness experienced a macular hemorrhage (bleeding in the retina) in his left eye without having other risk factors for hemorrhage. Ten weeks later the man experienced a second macular hemorrhage, at which time his doctor's learned that he began taking two 1,000-mg capsules of fish oil (providing 400 mg of DHA and 600 mg of EPA) daily beginning one month prior to the first bleeding event and continuing through the second event. After he discontinued the fish oil, the second hemorrhage healed within 8 weeks, and no further bleeding events were reported (Li, SAGE Open Med Case Rep 2020).

· If you take blood pressure lowering medication, be aware that fish oil may further lower blood pressure.

· Contrary to earlier reports, fish oil does not appear to adversely affect blood sugar levels in people with diabetes. However, a study in which a large amount of krill oil (including a modest amount of salmon oil) was given daily with water for 8 weeks to overweight, middle-aged men in New Zealand showed, to the researchers' surprise, that it reduced insulin sensitivity (by about 27%, factoring in potential benefits from EPA and DHA) and could, therefore, increase the risk of diabetes and cardiovascular disease. The men were given 5 grams (5,000 mg) of the oil daily (88% krill oil and 12% fish oil providing just 230 mg of EPA and 154 mg of DHA). Two men in the study (4%) withdrew after experiencing krill allergy; 47% reported experiencing "fishy burps." Due to the krill component, 42% of the oil used in the study was phospholipids. Phospholipids are not known to impair insulin sensitivity, but the researchers speculate that krill proteins attached to the phospholipids may have impaired insulin sensitivity (Albert, Am J Clin Nutr 2015).

· Despite some concern, taking fish oil long-term does not seem to adversely affect the liver. The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) considers fish oil to be unlikely to cause clinically apparent liver injury (LiverTox: Clinical and Research Information on Drug-Induced Liver Injury, 2012-2017). One study in rats given fish oil, virgin olive oil, or sunflower oil throughout their life (i.e., for 24 months) found that the animals given fish oil showed increased oxidation and decreased mitochondrial function in the liver, which the researchers stated might make the liver susceptible to nonalcoholic steatosis (NASH), a form of fatty liver disease. However, there was no worsening of fat content in the liver (steatosis), inflammation, severity of NASH, or fibrosis (liver scarring) compared to the animals fed with the other oils, although all three groups showed worsening of these outcomes over their lifetime, which was attributed to aging. The animals given fish oil also showed changes in the expression of certain genes that that may help the liver adapt to aging (Varela-Lopez, J Nutr Biochem 2018). Be aware, however, that taking fish oil containing large amounts of vitamin A (as is commonly found in fish liver oils, such as cod liver oil) can cause liver toxicity, particularly if taken with other supplements containing vitamin A.

· Some people are allergic to proteins in fish, krill, and calamari/squid (among other foods). Supplements are required to identify foods with allergic potential (including the species name) with a statement, e.g., "Contains: Fish (mackerel)." Not all of the fish oil products tested provided this complete labeling (those that did not have been indicated with a footnote in the sixth column in the results table above). It is possible that some manufacturers did not include this labeling because they considered the oil to be highly refined (and contain minimal protein). A small study among six fish-allergic patients administered fish oil supplements had no reaction to the supplements (Mark, Allergy Asthma Proc 2008). However, there is at least one case report of a person having a reaction to an "omega-3-6-9 fish oil capsule" (the specific product and its ingredients were not disclosed) (Kmet, Can Fam Phys 2012). In short, if you are allergic to fish, krill, or calamari, you may not have a problem with refined oils made from them, but use caution.

· Be aware that statins and other cholesterol-lowering drugs, like fenofibrate (Tricor), may alter the metabolism of omega fatty acids in the body, although this does not argue against using fish oil with these drugs. A 3-month study of men with high cholesterol showed that taking 200 mg of fenofibrate caused a significant decrease in the omega-3 fatty acids alpha-linolenic acid (ALA) and DHA, while among those taking 20 mg of a statin drug (simvastatin) there was a trend toward a decrease in all fatty acids, but it was not significant (de Lorgeril, Nutr Metab and Cardiovasc Dis 2005). Both groups experienced significantly increased blood levels of arachidonic acid, an omega-6 fatty acid -- which some researchers propose may inhibit the protective effects of omega-3 fatty acids (de Lorgeril, BMC Med 2013). More positively, a study in coronary heart disease patients already taking the statin drug simvastatin, but who continued to have high triglyceride levels, found that adding 2 grams twice a day of a highly concentrated omega-3 supplement (Omacor, which is discussed above under its current name, Lovaza) for 48 weeks decreased serum triglycerides by 20 — 30% and "bad" cholesterol - very low density lipoprotein (VLDL) - by 30 — 40% (Durrington, Heart 2001). Furthermore, a study using another highly concentrated fish oil (providing 1,800 mg of EPA daily) along with statin therapy in patients with coronary artery disease found that the added fish oil not only reduced triglyceride levels but also improved endothelial function in arteries, which is associated with better cardiovascular function (Toyama Cardiovasc Drugs Ther 2014).

· Possible serious side effects noted with prescription Lovaza and Epanova (i.e., concentrated fish oils taken at a high daily dose — up to 4 grams) are elevations in LDL-C (a form of "bad" cholesterol) and the liver function tests ALT and AST (2015 prescribing information for Lovaza and Epanova). Within the first few months of taking Lovaza, increases in the frequency of a heart rhythm problem (atrial fibrillation or flutter) may happen in people who already have that problem. Atrial fibrillation also occurred in 2.2% of people on 4 grams of Epanova daily compared to 1.3% on 4 grams of corn oil placebo (Nicholls, JAMA 2020). Vascepa has also caused an increase in the incidence of atrial fibrillation (3.1% vs 2.1% of patients treated with placebo (Bhatt, N Engl J Med 2018), and it can cause joint and throat pain (Vascepa prescribing information). Even a lower dose of concentrated fish oil (1.8 grams providing 930 mg of EPA and 660 mg of DHA) resulted in a trend toward increased incidence of atrial fibrillation (7.2% vs. 4% on placebo) in a two-year study among older people with recent heart attacks in Norway (Kalstad, Circulation 2020). A review of five large clinical trials (including the two trials noted above) using fish oil doses ranging from 840 mg to 4 grams per day, concluded that omega-3 supplementation is associated with an increased risk of atrial fibrillation in people with elevated triglyceride levels and/or cardiovascular risk (Lombardi, Eur Heart J Cardiovasc Pharmacother 2021); however, it should be noted all of these studies focused on people at increased cardiovascular risk, and the effects of fish oil supplementation on the risk of atrial fibrillation in healthy people is not known. Your physician should monitor you for atrial fibrillation and other potential side effects, particularly if you have had heart problems in the past.

· Fish oil (from supplements as well as fish) may interfere with chemotherapy. A fatty acid naturally found in fish oil known as 16:4(n-3) and into which other fatty acids, such as EPA, are converted in the body, has been shown in mice to activate white blood cells leading to resistance to chemotherapy. It is, therefore, advised to temporarily avoid fish oil from the day before chemotherapy until the day thereafter, as well as herring and mackerel (which raise 16:4(n-3) levels more than other fish such as salmon and tuna) in the 48 hours surrounding chemotherapy (Daenen, JAMA Oncology 2015).

· High-dose fish oil can increase blood levels of the immunosuppressant drug tacrolimus (sold as Astagraf, Envarsus, Protopic), as was demonstrated in a small study in Norway that showed blood concentrations of tacrolimus increased by 25% in organ transplant recipients who took 2,600 mg of omega-3 fatty acids daily (Lovaza/Omacor) for 4 weeks. This interaction may occur due to potential inhibition of intestinal CYP3A enzymes by omega-3 fatty acids. The researchers also warned that since the resulting increased systemic exposure of tacrolimus may not be reflected in "trough concentrations" (the lowest concentration reached by a drug before the next dose is administered) it may be difficult to monitor tacrolimus levels following the initiation and discontinuation of marine omega-3 fatty acid supplementation (Robertsen, Transpl Int 2021). High-doses of omega-3 fatty acids have been reported to raise levels of other immunosuppressant drugs metabolized by CYP3A enzymes, including cyclosporine (Neoral, Sandimmune) and sirolimus (Rapamune) (Cortinovis, Transplantation 2010; Busnach, J Nephrol 1998).

· Green-lipped mussel extract should not be taken by women who are pregnant or nursing, as an animal study suggests it may interfere with fetal development (Miller, N Z Med J 1984).

To further assist consumers, ConsumerLab.com licenses its flask-shaped CL Seal of Approved Quality (see The CL Seal) to manufacturers for use on labels of products that have passed its testing. ConsumerLab.com will periodically re-evaluate these products to ensure their compliance with ConsumerLab.com's standards.

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Information on this site is provided for informational purposes only. It is not an endorsement of any product nor is it meant to substitute for the advice provided by physicians or other healthcare professionals. The information contained herein should not be used for diagnosing or treating a health problem or disease. Consumers should inform their healthcare providers of the dietary supplements they take.

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Latest Clinical Research Updates for Fish Oil /Omega-3 Fatty Acid Supplements

Fish Oil for COVID?

11/18/2021

Does taking concentrated fish oil reduce hospitalizations or deaths in people with COVID? Find out what a study showed in the COVID section of our Fish and Marine Oil Supplements Review.

Trout for Omega-3s?

10/26/2021

Is trout a good alternative to tuna or salmon as a source of omega-3 fatty acids? It depends on the type of trout. Get the details in the Getting EPA and DHA from Food section of our Fish Oil Supplements Review. Also see our Top Picks for fish oil supplements and canned fish.

Caveat With Prescription Fish Oil Study

8/31/2021

Some of the cardiovascular benefit reported for a prescription fish oil may have actually been due to a problem with the placebo to which it was compared, according to new research. Get the details in the Prescription Fish Oil vs Supplements section of our Fish Oil Supplements Review. Also see our Top Picks among fish oil supplements.

Omega-7s for Muscle Pain?

8/21/2021

Can supplementation with omega-7 fatty acids (from fish oil) reduce muscle pain or inflammation in the body? See what a new study found, and learn if omega-7s have other benefits in the omega-7 section of our Fish Oil Supplements Review. Also see how much omega-7 we found in popular fish oil products.

Statins Plus Fish Oil?

7/31/2021

Can taking high-dose omega-3s decrease triglyceride levels in people taking a statin drug? See what a new study found in the Taking With Statins section of our Fish Oil Supplements Review. Also see our Top Picks among fish oil supplements, including highly concentrated products.

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