Black Currant Oil, Borage Oil, Evening Primrose Oil,
Flaxseed Oil, and Hemp Oil Supplements Review: Sources of ALA and GLA (Omega-3
and -6 Fatty Acids)
Choose the Best Seed Oil
Supplements. Find Out Which Flaxseed and Other Seed Oil Supplements Passed Our
Tests.
Medically reviewed and
edited by Tod Cooperman, M.D. 
Last Updated
: 06/08/2021 | Initially Posted:
11/18/2017Latest Update: Black Seed for COVID?
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Table of Contents
Summary
·
Does it work? These seed oils contain predominately
healthful, polyunsaturated fats such as ALA (as from flax) and/or GLA (as from
evening primrose) (See "What It Is"). Substituting these for
saturated fats in your diet can lower your risk of cardiovascular disease.
Taken as a supplement, they may help with the following conditions, although
the evidence remains only preliminary: acne, ADHD, dry eye, bipolar disorder,
diabetic neuropathy, mastitis, eczema, rheumatoid arthritis, and Raynaud's
phenomenon. (See "What It Does").
·
What dose? Depending on the
use, studies have used daily doses of seed oils that provide from as little as
15 mg to as much as 2,000 mg of ALA or GLA. (See "Dosage"). Keep in mind that only a part
of the seed oil is ALA or GLA, so the amount of oil needed could be double or
even 10 times higher than the dose of ALA or GLA. For example, about 55% of
flaxseed oil is ALA, so a tablespoon of flaxseed oil (weighing about 14,000 mg)
provides about 7,700 mg of ALA, while evening primrose oil is only 7 to 10% GLA
(about 1,200 mg per tablespoon). (See "What to Consider When Buying")
·
Best choice? ConsumerLab.com's tests found
that most products were high-quality, although three failed to pass tests for
freshness. See CL's Top Picks among
products that were Approved.
·
Cautions Although generally safe, these oils can cause mild nausea
and diarrhea, but there are ways to lessen this. Rarely, allergic reactions to
flaxseed have been reported. Use these oils with caution if you are pregnant,
have a seizure disorder, hemophilia, take blood-thinning medication, or are
considering use in an infant. (See "Concerns and Cautions").
What It Is:
ALA:
ALA (alpha-linolenic acid) is an omega-3 essential fatty acid. An essential
fatty acid is one that the body needs but must be supplied by the diet, since
the body cannot manufacture it or cannot manufacture enough of it. From ALA,
the body has a limited ability to manufacture two other important omega-3's —
EPA (eicosapentaenoic acid) and DHA (docosahexaenoic
acid) -- it can convert small amounts of ALA into EPA and is even less
efficient in making DHA. It is estimated that between 5 to 10% of dietary ALA
may be converted into EPA, and about 2 to 5% may be converted into DHA (Davis, Am J Clin Nutr 2003),
although conversion may be somewhat higher in young women as well as vegans and
non-fish eating vegetarians (Burdge, Br J Nutr 2002; Welch, Am J Clin Nutr 2010).
Among plant seeds, flaxseed (also known as flax seed (Linum usitatissimum)
or linseed) contains among the highest concentration of ALA — in fact, 55% of
the oil in flaxseed is ALA. Chia seed also has a very high concentration (58%)
of ALA in its oil, although the seed itself has less total oil than flaxseed.
Phytoplankton and algae are also rich sources of ALA. The oil from hemp and black
currant seeds also contain, respectively, 19%
and 13% ALA. Soybean oil, canola oil, and walnuts also contain some ALA.
GLA:
GLA (gamma-linolenic acid) is an omega-6 fatty acid. The body ordinarily is
able to produce sufficient GLA from another omega-6 fatty acid, linoleic
acid (LA), which is an essential fatty acid found in foods containing oils
from corn, sunflower, safflower, soy, peanut and other plants, including flaxseed. However,
GLA production might be reduced in several conditions (advanced age, diabetes,
high alcohol intake, eczema, excessive saturated fat intake, elevated
cholesterol, and some vitamin/mineral deficiencies.) In such cases, it is
possible that supplementation may be beneficial. Seed oils from black
currant (Ribes nigrum), borage (Borago
officinalis), and evening primrose (Oenothera biennis) are among the few that are rich in GLA. Hemp seed
oil also contains a small amount. All of these oils are also rich in linoleic
acid.
Both ALA and GLA, as well as LA, are polyunsaturated fats ("good"
fats, as opposed to saturated fats that may increase the risk of heart
disease).
What It Does:
ALA:
The Mediterranean diet, which has been associated in observational studies with
a lower risk of coronary artery disease and possibly certain
types of cancer, is high in ALA. A diet rich in ALA also appears to
reduce the risk of high blood pressure. However, ALA taken by itself
has not been shown to significantly decrease the risk of cardiovascular
disease. In contrast, the omega-3 fatty acids "downstream"
from ALA, EPA and DHA, have shown potential for reducing triglyceride levels
and improving HDL levels (two important aspects of the cholesterol profile) and
provide benefits for a variety of other conditions, including rheumatoid
arthritis and menstrual pain not thought to occur
with ALA intake. While they are all omega-3 fatty acids, the benefits of EPA
and DHA are not directly transferable to ALA. (See our Product
Review of Omega-3 Fatty Acids from Fish and Marine Oils for
more information about EPA and DHA).
Flaxseed oil (the most common source of ALA) has no well-documented
specific medical uses but may be useful as a dietary supplement for people who
are not getting EPA or DHA from fish/marine oils. Nevertheless,
a small study in Japan did find that, among middle-aged men with elevated triglycerides (>100
mg/dL), consuming 10 grams (10,000 mg) of flaxseed oil (containing 5,500 mg of
ALA) with dinner for 12 weeks led to a significant and meaningful decrease in
small dense LDL cholesterol (sdLDL)
— the form of LDL ("bad cholesterol") most associated with plaque
formation and cardiovascular disease. The flaxseed oil did not lead to any
other statistically significant changes in cholesterol (although, compared to
taking the same amount of corn oil, it appeared more likely to lower total
cholesterol, total LDL, and the portion of cholesterol known as apoB, but it was also more likely to lower HDL
"good" cholesterol) and did not decrease triglyceride levels
(Kawakami Nutri J 2015). Other studies have
also failed to show improved triglycerides from ALA (Rodriguez-Leyva, Can J Cardiol
2010), although one study among healthy adults with normal
triglyceride levels found that consumption of flaxseed oil (providing 6 grams
of ALA per day) for one month significantly decreased triglyceride levels (by
20%) in younger adults (18 — 29) but not in older adults (ages 45 — 69) (Patenaude, Eur J Clin Nutr 2009).
Flaxseed oil was not found to help
lower blood pressure when compared to placebo in people with
high-normal blood pressure or stage 1 hypertension. People in the study
consumed 5 grams of refined, cold-pressed flaxseed oil twice daily with meals
(providing 4,700 mg per day of ALA) for three months or a placebo (high-oleic
sunflower oil) (Pieters, Br J Nutr
2018). Interestingly, consuming flaxseeds (rather than refined
flaxseed oil) has been shown to decrease blood pressure in some people with
hypertension, as discussed further below (see below).
There is preliminary evidence that flaxseed oil might
reduce hyperactivity and other symptoms of ADHD in
children. Preliminary studies have also suggested possible benefit of flaxseed
oil in preventing dry eye in Sjogren's syndrome (an autoimmune
condition) and as an adjunct to conventional treatments for bipolar
disorder.
Flaxseeds themselves
contain fiber and lignans that are phytoestrogens and might be useful in
preventing cancer, lowering cholesterol levels, and
improving menopausal symptoms. However, flaxseed oil contains
little or no lignans because lignans are bound to the fiber, which is lost when
the oil is pressed from the seeds. (Some specially processed flaxseed oils
contain lignans, which are reintroduced after the oil is pressed.) A small, but
controlled, study in people with peripheral arterial disease (75% of whom had
high blood pressure) found that consuming 1 ounce of milled
flaxseed (30 grams) per day lowered blood pressure. After 6 months, systolic
blood pressure was about 10 mm Hg lower, and diastolic blood pressure was about
7 mm Hg lower in the flaxseed group compared with a placebo group. Patients who
started the trial with a systolic blood pressure of at least 140 mm Hg obtained
a reduction of 15 mm Hg in systolic blood pressure and 7 mm Hg in diastolic
blood pressure (Rodriguez-Leyva,
Hypertension 2013). Further analysis of the results led researchers
to theorize that ALA in flaxseed may play a role in blood pressure reduction
through inhibition of the enzyme epoxide hydrolase which, in turn, reduces
levels of oxylipin compounds that regulate vascular tone (Caliguri, Hypertension 2014).
Although not a focus of this product review, another
plant source of ALA is echium oil (from seeds of Echium plantagineum ), which contains stearidonic
acid SDA, a fatty acid also found in hemp and black currant and which is more
easily converted to EPA than ALA, as well as GLA (Botelho, Lipds Health Dis 2013). Daily supplementation
with 15 grams of echium oil (taken in divided doses with meals) has been shown
to significantly increase blood levels of EPA, but not DHA (Surette, J Nutr 2004). Compared to supplementation with EPA from fish
oil (17 grams of fish oil containing 1,900 mg EPA daily), one clinical study
found echium oil (17 grams per day) had a similar triglyceride-lowering effect;
however, unlike EPA from fish oil, echium oil also lowered levels of total and
"bad" LDL cholesterol (Kuhnt, J Nutr 2014).
As noted above, chia seeds are also a source of ALA and,
consequently, can modestly increase blood levels of EPA (not DHA), but chia has
not been shown to improve risk factors for cardiovascular disease (Ferreira, Nutr Hosp 2015).
GLA:
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 2 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 grams of 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.
Other Uses:
GLA may help treat diabetic neuropathy. It has been used in Europe
to treat cyclic mastitis (breast pain associated with the
menstrual cycle) and eczema. However, the evidence for cyclic
mastitis is weak and recent evidence indicates that it does not work for
eczema. In fact, a review of data from 27 studies of either evening primrose
oil or borage oil for eczema did not find taking either allayed eczema any more
than taking placebo (Cochrane
Library 2013). GLA may have some benefit in treating rheumatoid
arthritis (especially as purified GLA and when combined with
traditional treatments) and Raynaud's phenomenon.
A 45-day study also found that a combination of linoleic acid and GLA
might improve symptoms of aqueous-deficient keratoconjunctivitis sicca (dry
eye syndrome), a condition in which the surface of the eye is dry and
inflamed (Barabino, Cornea 2003).
A more recent and longer (6-month) study of a supplement containing black
currant seed oil in post-menopausal women with dry eye also showed
improvement in symptoms of irritation, better maintenance of smoothness of the
cornea, and suppression of inflammation compared to placebo (Sheppard, Cornea 2013). The daily dose given
(4 softgels) provided 1,570 mg of black currant seed
oil (consisting of 240 mg GLA, 196 mg ALA, 710 mg of LA) in a formula (HydroEye, ScienceBased Health) which also provided fish oil (126 mg
EPA and 99 mg DHA), 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.)
Many of the clinical effects
of GLA have been attributed to its anti-inflammatory effects. In
the body, GLA is converted to dihomo-gamma linolenic
acid (DGLA), which can bind to cyclooxygenase (COX) and lipoxygenase (LOX)
enzymes and be converted to anti-inflammatory metabolites. However,
DGLA can also be converted to arachidonic acid, which also binds to COX enzymes
but is converted to pro-inflammatory metabolites (Sergeant, Eur J Pharmacol 2016).
It is possible that these conflicting actions partially explain some of the
weak or inconsistent evidence regarding GLA for inflammatory conditions.
Most clinical studies of GLA have used evening primrose seed
oil, the most popular and widely available source of GLA on the market. Many other
potential uses, including some in conjunction with fish oils, have been
explored for GLA, but the evidence is either weak or preliminary.
For dosages and other information see ConsumerTips™.
Pet Use:
Seed oil supplements, as well as fish oil supplements, are commonly given to
pets to help maintain their coats and skin. [Reviews of other pet supplements
by ConsumerLab.com include Fish Oils, Joint Supplements, Probiotic Supplements and Multivitamins/Multiminerals.]
Quality Concerns and
Tests Performed:
Because
omega-3 and 6 fatty acids are obtained from natural sources, levels in
supplements can vary, depending on the source and method of processing. The
freshness of the oil is also an important consideration because rancid oils
have an unpleasant taste, odor, and can cause gastrointestinal side effects.
They may also not be as effective due to degradation. In addition, rancid fat
contains chemicals called peroxides and aldehydes that can damage cells and may
even encourage cholesterol to clog arteries. Vitamin E is often added to
omega-3 and -6 supplements because its antioxidant properties are thought to
protect against rancidity. However, as ConsumerLab.com has reported in the
past, the addition of vitamin E is no guarantee of freshness, nor is it a
requirement for freshness. Neither the FDA nor any other federal or state
agency routinely tests omega-3 and 6 fatty acid supplements for quality prior
to sale, although ConsumerLab.com has reported problems with such products in
the past. 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. and Canada claiming to contain ALA, GLA, LA or
related seed oils and tested them for signs of decomposition and their levels
of these and other omega-3 or omega-6 fatty acids claimed on their labels. If
claims were not made for levels of specific fatty acids, products were held to
certain minimum expected amounts based on the seed oils used (see Testing Methods and Passing Score for
more information).
Products containing milled seed or whole herb were also tested for contamination
with the heavy metals lead, cadmium and arsenic. In children, infants, and
fetuses, even low levels of lead can adversely affect neurobehavioral
development and cognitive function. In adults, lead at somewhat higher levels
can cause elevated blood pressure, anemia, and adversely affect the nervous and
reproductive systems. Lead is of particular concern during pregnancy as the
mother can transfer it to the fetus. Cadmium is a carcinogen and kidney toxin.
Arsenic is a carcinogen and can damage organs.
What CL Found:
ConsumerLab.com purchased and tested supplements made from the
seed oils of black currant, borage, flax, and evening primrose, as well as
combination products (including some with fish oil). Among the seventeen
products selected by ConsumerLab.com, fourteen passed testing. (See How Products Were Evaluated for more information
about testing). Each of the three oils that did not pass testing were found
have high levels of oxidation, and indication of spoilage. To be considered
"fresh," the level of active oxygen, known as peroxide, should not
exceed 10 milliequivalents (meq) per kilogram of
processed oil or 15 meq of "cold pressed"
oil. The following three oils were each above these limits, although none had a
peroxide level above 30 meq, which would suggest a
rancid taste:
·
PipingRock.com Black Currant Seed Oil — Peroxide value of
12 meq/kg, exceeding limit of 10 meq/kg
for processed oils
·
Nature's Answer Liquid Evening Primrose Oil — Peroxide value of
14 meq/kg, exceeding limit of 10 meq/kg
for processed oils
·
Nutiva Hemp Oil — Peroxide value of
17 meq/kg, exceeding limit of 15 meq/kg
for cold pressed oils
All products contained
their listed amounts of ALA, GLA, and other listed fatty acids, except
for Nutiva Hemp Oil which
contained somewhat less than the listed amounts of stearidonic
acid and total omega-9 fatty acids, as shown in the Results table below.
These findings were confirmed in a second, independent laboratory.
Ten additional products passed testing through ConsumerLab.com's
voluntary Quality Certification Program.
These products are indicated with a CL flask beside their names in the table
below.
Top Picks:
To help
you get omega-3 and -6 fatty acids from the tested products at high quality and
lowest cost, see the Results table below. The last column
shows the cost of a suggested daily serving of each product and, for
single-ingredient products, the cost to obtain a specific amount of one of the
key omega-3 or -6 fatty acids, i.e., 200 mg of GLA or 500 mg of ALA. Based on
this cost comparison, the following Approved products appear to provide some of
the best values:
Black Currant Oil — Solaray
Black Currant Seed Oil is CL's Top Pick for black
currant oil, although twice the price of the other tested product, PipingRock.com,
which appeared to be stale based on peroxide testing. A softgel
of Solaray provides 72 mg of ALA and
90 mg of GLA for 16 cents. Interestingly, the amount of seed oil per pill in
both products (500 to 600 mg) is about half the amount in other products in
this review (1,000 to 1,300 mg).
Although not tested this year, ScienceBased
Health HydroEye — a combination of black
currant oil and fish oil -- was approved for quality when tested by
ConsumerLab.com in 2014. It is for relief of dry eyes and includes vitamins. It
is relatively expensive (about $39 per 120 softgels,
with a daily serving of 4 softgels). If you want fish
oil, it may be much less expensive to purchase a separate fish oil supplement —
we have identified many that cost only pennies per day. (Be aware that there
are also supplements made from black currant fruit, rather than
seed, on the market, but these do not contain omega-3 oils.)
Borage Oil — The lowest cost to obtain 200 mg of GLA from borage
oil was 10 cents, from Life Extension Mega GLA with Sesame Lignans —
each softgel provides 299 mg of GLA for 15
cents.
Evening Primrose Oil — The lowest cost to obtain 200 mg of GLA from
evening primrose oil was 14 cents from Trunature
[Costco] Evening Primrose Oil which provided that much per softgel.
Flaxseed Oil — The lowest cost to obtain ALA from flaxseed oil was
from Member's Mark [Sam's Club] Natural Flaxseed Oil, which
provided 1300 mg of ALA per softgel costing just 9
cents (2 cents per 500 mg of ALA).
Hemp Oil — Only Manitoba Harvest Hemp Oil was
approved among the two hempseed oils tested. Manitoba is relatively expensive
as a source of ALA, costing 39 cents per 500 mg of ALA versus as little as 2
cents from flaxseed oil, as noted above.
Nutiva Hemp Oil was a less
expensive source of ALA (just 6 cents per 500 mg) than Manitoba,
but it failed to be Approved because, as mentioned earlier, it appeared to be
stale in peroxide testing and had lower amounts of stearidonic
acid (which can be converted to EPA) and omega-9 fatty acids than listed.
Hemp oil naturally contains a very small amount (about 0.0025%) of cannabidiol,
or CBD. ConsumerLab determined the amounts of CBD in
the two hemp oils, finding only small amounts (well under 1 mg per serving), as
expected. ConsumerLab has separately tested products
that claim to contain larger amounts of CBD (see CBD Oil and Hemp Extract Review).
Be aware that hemp seed and seed oil may also contain very small amounts
of THC, the psychoactive compound in hemp.
Combination Products — In addition to testing oils from individual
plant sources, ConsumerLab purchased and tested two
products made from combinations of seed oils. Both were Approved, but Flora
Udo's Choice Udo's Oil (flaxseed and evening primrose oil), which cost
80 cents per tablespoon, is CL's Top Pick in this category due
to its higher concentration of ALA -- 5,000 mg per tablespoon, indicating that
36% of the oil is ALA. The Vitamin Shoppe Omega-3-6-9 (made
from flaxseed oil and borage oil, as well as canola, salmon, and safflower oil)
was also Approved. It has a much lower concentration of ALA, but a higher
concentration of GLA than Udo's, although the amounts per 2 softgel serving are modest — 60 mg and 50 mg,
respectively.
Pet Supplements — The two products tested were both Approved but
are quite different from one another. HALO Purely For
Pets is a combination of many types of oil, while The Missing
Link Ultimate Canine is a powder of just ground flaxseed. Both are
rich in linoleic acid (LA), with HALO providing 5,670 mg of LA as well as 540
mg of ALA per 3 teaspoons of oil (for 71 cents) and The Missing Link providing
1,333 mg as well as 600 mg of ALA per 4 teaspoons of powder (41 cents). HALO is
a less expensive source of LA, while The Missing Link is a
less expensive source of ALA. Either would be a good source of oils.
Test Results by Product:
Listed
alphabetically below are the test results for twenty-seven dietary supplements
containing ALA and/or GLA. They are grouped by the source of seed oil — black
currant, borage, evening primrose, flaxseed, hemp, combinations, or oils for
pets. Seventeen were selected by ConsumerLab.com (of which two are marketed
specifically for pet use). Ten others (each indicated with a CL flask icon)
were tested at the request of their manufacturers/distributors through
CL's Quality Certification Program. Also listed is
one product similar to another that passed but that is sold under a different
brand name.
Products listed as "Approved" met their label claim and ConsumerLab.com's standards for omega-3 fatty acid
products. Also shown are the claimed amounts per daily suggested serving of
ALA, GLA, LA (linoleic acid) and other fatty acids claimed on the label. The
full list of ingredients is available for each product by clicking on the word
"Ingredients" in the first column. Price and cost comparisons, as
well as notable features, are included in the last column.
|
RESULTS OF CONSUMERLAB.COM TESTING OF BLACK CURRANT, BORAGE,
EVENING PRIMROSE, FLAXSEED AND HEMP OIL PRODUCTS: |
||||||
|
Product Name, Serving
Size and Suggested Daily Serving on Label |
Claimed Amount of
Specific Fatty Acids Per Labeled Daily Serving |
--TEST RESULTS-- |
Cost For Daily
Suggested Serving On Label |
|||
|
OVERALL RESULTS: |
Contained Labeled
Amounts of Oils |
Did Not Exceed
Contamination Limit for Lead, Cadmium and Arsenic2 |
Freshness3 |
|||
|
|
Black Currant Seed Oil: 500 mg |
NOT |
|
NA |
Found peroxide value of
12 meq/kg |
$0.07 |
|
|
Black Currant Seed Oil: 600 mg |
APPROVED |
|
NA |
|
$0.16-$0.48 |
|
[Cost Per 200 mg of GLA] |
||||||
|
|
Borage Seed Oil: 1,150 mg |
APPROVED |
|
NA |
|
$0.34 |
|
|
Borage Seed Oil: 1,200 mg to 2,400 mg |
APPROVED |
|
NA |
|
$0.15-$0.29 |
|
|
Borage Seed Oil: Amount not listed |
APPROVED |
|
NA |
|
$0.15-$0.73 |
|
|
Borage Seed Oil: 1,300 mg to 2,600 mg |
APPROVED |
|
NA |
|
$0.26-$0.52 |
|
|
Borage Seed Oil: 1,300 mg |
APPROVED |
|
NA |
|
$0.32 |
|
[Cost Per 200 mg of GLA] |
||||||
|
|
Evening Primrose Oil: 2,000 mg |
NOT |
|
NA |
Found peroxide value of
14 meq/kg |
$0.35 |
|
|
Evening Primrose Oil: 3,000 mg |
APPROVED |
|
NA |
|
$0.67 |
|
|
Evening Primrose Oil: 3,000 mg |
APPROVED |
|
NA |
|
$0.50 |
|
|
Evening Primrose Oil: 1,300 mg to 2,600 mg |
APPROVED |
|
NA |
|
$0.19-$0.39 |
|
|
Evening Primrose Oil: 3,000 mg |
APPROVED |
|
NA |
|
$0.24 |
|
|
Evening Primrose Oil: 1,000 mg to 3,000 mg |
APPROVED |
|
NA |
|
$0.73-$2.18 |
|
|
Evening Primrose Oil: 2,000 mg to 3,000 mg |
APPROVED |
|
NA |
|
$0.14-$0.21 |
|
|
Evening Primrose Oil: 2,600 mg |
APPROVED |
|
NA |
|
$0.55 |
|
Puritan's Pride® Evening Primrose Oil (1 softgel, once to five times daily) |
Similar to Vitamin
World Evening Primrose Oil |
$0.25-$1.25 |
||||
|
[Cost Per 500 mg of ALA] |
||||||
|
|
Flaxseed Oil: 14,000 mg to 28,000 mg |
APPROVED |
|
NA |
|
$0.48-$0.96 |
|
|
Flaxseed Oil: 2,600 mg |
APPROVED |
|
NA |
|
$0.16 |
|
|
Flaxseed Oil: Amount not listed |
APPROVED |
|
NA |
|
$0.58 |
|
|
Flaxseed Oil: 2,600 mg to 3,900 mg |
APPROVED |
|
NA |
|
$0.09-$0.13 |
|
|
Flaxseed Oil: 2,400 mg to 3,600 mg |
APPROVED |
|
NA |
|
$0.24-$0.36 |
|
|
Flaxseed Oil: 3,000 mg to 9,000 mg |
APPROVED |
|
|
|
$0.39-$1.16 |
|
[Cost Per 500 mg of ALA] |
||||||
|
|
Hemp Oil: Amount not listed |
APPROVED |
|
NA |
|
$0.41 |
|
|
Hemp Oil: 14,000 mg9 |
NOT |
Found only 195 mg stearidonic acid (78.0% of listed amount) and only 1,365
mg total omega-9s (68.3% of listed amount) per serving |
NA |
Found peroxide value of
17 meq/kg |
$0.299 |
|
|
Flaxseed Oil: Amount not listed |
APPROVED |
|
NA |
|
$0.809 |
|
|
Flaxseed Oil: 150 mg |
APPROVED |
|
NA |
|
$0.17 |
|
|
Soybean oil, safflower oil, sunflower oil,
wheat germ oil, cod liver oil, anise oil, garlic oil. Amounts not listed. |
APPROVED |
|
NA |
|
$0.12-$0.71 |
|
|
Ground flaxseed: Amount not listed. |
APPROVED |
|
|
NA15 |
$0.05-$0.41 |
|
|
||||||
|
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. |
||||||
|
Copyright ConsumerLab.com, LLC, 2017. All rights reserved.
Not to be reproduced, excerpted, or cited in any fashion without the express
written permission of ConsumerLab.com LLC. |
||||||
ConsumerTips™:
Getting ALA and GLA From
Supplements: When buying supplements, keep in mind that products vary
significantly in terms of the amounts and ratios of the various fatty acids.
Also, products may contain other vegetable oils that do not provide GLA or ALA,
so watch out for products claiming a "complex," "formula,"
or "blend" that do not specifically state the amount of GLA and ALA.
Also be aware that some supplements may contain parts of plants, other than the
seed, which may contain no oil at all, such as a black currant supplement made
from black currant "fruit," rather than from seed.
You may find that many products contain vitamin E or another antioxidant, which
is added to prevent the oils from becoming rancid — although, this is not a
guarantee against rancidity. Spoilage, even in softgels,
may be detectable by an "off" smell, taste, or feel, but is often
difficult to discern unless you are familiar with specific oils in their fresh
state.
Note that one tablespoon (equal to 3 teaspoons) of any of these oils is 15 mL
or about 14,000 mg (14 grams) of oil, of which a percentage will be ALA or GLA
as discussed below.
Getting ALA and GLA From Food:
Flaxseeds are rich in ALA. One tablespoon of flaxseed oil that is 55% ALA
contains about 7,600 mg of ALA. Nuts, especially walnuts, are also a good
source, as are green leafy vegetables, particularly purslane. ALA is also
available from eggs specially produced from hens fed flaxseed.
All of the seed oils covered in this review contain some saturated fat (6 to
11%), although nowhere near the levels seen, for example, in coconut and palm
kernel oils — which contain 91% and 85% saturated fat and no GLA nor ALA.
Is Omega-6 a Problem?
Some experts feel that the American diet contains too little omega-3 fatty
acids (such as ALA, DHA, and EPA) and too much omega-6 fatty acids
(particularly LA, which is found in soybean, safflower and corn oils). Because
they compete with each other for certain enzymes needed in their metabolism,
the concern is that too much omega-6 in the diet may interfere with the body's
conversion of ALA into DHA, and may promote inflammation in the body. The ratio
of omega-6's to omega-3's in the American diet may be as high as 14:1 (14 grams
of omega 6's for every gram of omega-3's), but a ratio of no more than 3:1 is
recommended by some authorities. However, extensive evidence (including a
systematic review of 30 randomized controlled trials) shows that, overall,
the omega-6 unsaturated fat linoleic acid (LA) does not have
an inflammatory effect (Innes, Prostaglandins Leukot
Essent Fatty Acids 2018; Su, Food Funct 2017).
Nevertheless, a study among men in Finland suggests that a common genetic
variant in the FADS1 gene -- which regulates fatty acid metabolism -- can cause
an inflammatory response to omega-6 fatty acids. The study found that adding a
large amount (2 to 3 tablespoons) of LA-rich (62%) sunflower oil to the diet
raised a measure of inflammation (CRP) only in those with the FADS1 genetic
variant (Lankinen, Am J Clin Nutr 2019).
About 33% to 42% of people have this variant, according to studies in China and
Finland (Zhu, J Lipid Res 2013; Takkunen, Mol Nutr Food Res
2016).
What to Consider When Using:
ALA
As ALA and LA are essential nutrients, the Institute of Medicine of the
National Academies has established daily Adequate Intake (AI) levels for both.
These are the daily amounts that you need to get in total from your foods
and/or supplements. Much higher amounts of LA are needed than ALA.
The daily adequate intake amount for LA is 7,000 mg (7 grams) for children 1 to
3 and 10,000 mg for those 4 to 8. For older individuals, the AIs depend on
gender. Among males, the AI is 12,000 mg for those 9 - 13, 16,000 mg for those
14 to 18, 17,000 mg for those 19 to 50, and 14, 000 mg for men over 50 years of
age. Among women, the AI is 10,000 mg for those 9 - 13 and 11,000 to 12,000 mg
for those 14 or older — although 13,000 mg for women who are pregnant or
nursing. The daily intake amounts for ALA are generally one-tenth of those for
LA. For example, the AI for women is 1,100 mg — and slightly higher for women
who are pregnant or nursing.
For treating ADHD, flaxseed oil providing 200 mg of ALA with 25 mg of vitamin C
taken twice daily has been used.
For treating dry eye symptoms in the autoimmune disease Sjogren's syndrome, 1
to 2 grams daily of flaxseed oil have been used.
The typical serving of flaxseed oil is 1 to 2 tablespoons
daily. ALA makes up about 40 to 60% of flaxseed oil, or about 7,000 mg per
tablespoon, while linoleic acid makes up about 15% (210 mg). The amount of
lignans is typically high in flaxseeds, but completely absent in flaxseed oils,
since it is associated with the fiber in flax — which is removed when
processing the oils. However, some specially prepared oils will contain the
lignans (which are added back after the oil has been pressed from the seed). It
can be taken as a capsule or used as an oil in foods that are not cooked, such
as salads. When using whole flaxseed, a typical dose is 1 tablespoon of the
ground seeds sprinkled on foods or taken with fluids 2 to 3 times a day. You
will not get all the potential benefit of the oil if the seeds are swallowed
whole, so be sure to chew them well or use ground seeds. GLA
Dosage for GLA (from evening primrose, borage, black currant or other seed
oils) can be described either in terms of the milligrams (mg) of GLA oil or the
equivalent amount of seed oils that contain the GLA. Borage oil is about 17% to
25% GLA (about 3,000 mg per tablespoon), black currant oil is about 15% to 20%
GLA (about 2,500 mg per tablespoon) (and also contains 12% to 14% ALA), and
evening primrose oil is about 7 to 10% GLA (about 1,200 mg per tablespoon),
although it has become the most common source of GLA.
Diabetic neuropathy is typically treated with about 400 to 600 mg of GLA daily
(about 4 to 6 g of evening primrose oil or 2 to 3 grams of borage oil), mastalgia (breast pain) with 3 to 4 g of evening primrose
oil, and rheumatoid arthritis ranges from 360 mg to as much as 2,000 to 3,000
mg of GLA from borage seed oil (best obtained from purified GLA when higher
doses are used).
In treating the eye disease aqueous-deficient keratoconjunctivitis
sicca (dry eye), a combination of linoleic acid (28.5 mg
twice daily) and GLA (15 mg twice daily) has been used, as has a formula (HydroEye)
consisting of black currant seed oil (1.57 grams daily) with fish oil, vitamins
A, B6, and C and magnesium.
For acne, a daily dose of 400 mg GLA (from 2 grams of borage oil), taken for 10
weeks, was found to significantly reduce the number and severity of lesions in
men and women ages 18 to 33 years old (Jung Acta Derm
Venereol 2014).
It is believed that treatment with the oils can take up to 6 months for a full
effect. Also, it may be best to take these supplements in divided doses, i.e.,
divide the dose in half and take twice daily, or in thirds and take three times
a day.
Because they are unsaturated fats, ALA, GLA, and LA can be
damaged by exposure to heat, light and oxygen. Consequently, they should
ideally be stored in a cool, dry place and in a well-sealed, opaque container.
They also should not be used for cooking, as this will destroy them.
Concerns and Cautions:
While
omega-3 and 6 supplements are generally considered safe, there are a few
concerns and cautions you should take into consideration before you buy:
·
All products containing omega-3 or omega-6 fatty acids may cause
mild gastrointestinal symptoms including nausea and diarrhea. This may improve
by taking smaller doses throughout the day and by trying another brand in case
the one you are using is spoiled. Those with seizure disorders should use
caution when supplementing with GLA (such as borage oil and evening primrose
oil) as it may lower the threshold for seizure.
·
These products should be used only under a physician's care by
hemophiliacs, those taking prescription blood thinners, such as Coumadin
(warfarin) or heparin, and those expecting to undergo surgery. Their use should
be stopped prior to surgical procedures.
·
Although unlikely, interactions could, in theory, occur between
supplements and other "blood thinning" substances such as aspirin or
other non-steroidal anti-inflammatory drugs and herbs such as garlic and
ginkgo.
·
These products should not be used by infants and pregnant or
nursing mothers as they may affect omega-3 production, which is important to
neurological development. Use of evening primrose oil, in particular, may be
associated with increased incidence of complications during labor and delivery.
·
Lignan in some flaxseed products could potentially have an
estrogenic effect, inducing menstruation.
·
Parts of the borage plant (leaves and roots) contain
pyrrolizidine alkaloids that are potentially toxic to the liver and
carcinogenic. While present in the plant, the alkaloids are not extracted with
the seed oil. For this reason, products in this review were not tested for
pyrrolizidine alkaloids because they were labeled as made from seed oils.
·
A study released in 2004 suggested that increased intakes of
dietary ALA might increase the risk of advanced prostate cancer, although it
was not associated with an increase in the total cases of prostate cancer. A
2007 study suggested that increased intakes of ALA might contribute to the
development or progression of age-related cataracts (Lu, J Am Coll Nutr 2007).
·
Rarely, allergic reactions to flaxseed, including vomiting,
shortness of breath, hives and anaphylaxis have been reported (Leon, Allergol Immunopathol 2013; Alonso, J Allergy Clin Immunol 1996).
·
Some supplements combine seed oils with fish oils. People who
are allergic to fish proteins should be cautious with such products.
Supplements are required to identify foods with allergic potential (including
the species name) with a statement, e.g., "Contains: Fish
(mackerel)." However, CL has found that not all of products provide this
complete labeling (those in this review that did not have been indicated with a
footnote in the fourth 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). In any event, if you
have an allergy to fish or krill, be cautious with products made of their oils,
even if highly refined.
·
Consuming hemp seeds or hemp oil could cause a positive result
on a blood test for THC, but because amounts of THC in hemp seeds used for
these products are so low, you would have to consume large amounts. For
example, to get 0.6 mg of THC, you would typically have to consume 8
tablespoons of hemp oil or 300 grams (about 30 tablespoons) of hulled hemp
seeds (Leson J Anal Toxicol 2001).
However, there can be large variations in the amounts of THC in hemp seeds. An
analysis of three brands hemp seed purchased from grocery stores in Canada
found that all three exceeded Canada's legal limit for THC in hemp (10 mcg/g)
and one was 7-to-12 fold higher than this limit, such that
only 30 grams (about 3 tablespoons) would provide 3.8 mg of THC (Yang, Cannabis Cannabinoid Res 2018). There is
also a report of a man who consumed two tablespoons of cold-pressed hemp oil ( Hemp Liquid Gold , Health From the
Sun) for four days and tested positive for THC on a standard drug test. The
amount of THC in the product was not reported (Struempler, J Anal Toxicol 1997). Due to these possibilities,
some branches of the U.S. military, including the Army, Air Force and Coast
Guard forbid the use of any hemp-based
products, including hemp oil, hemp seeds, and foods that contain
hemp, such as yogurt containing hemp seeds.
Interestingly, the World Anti-Doping Agency, which helps to oversee drug
policies in sports, announced in 2018
that cannabidiol is no longer prohibited by the organization, but cautioned
that " cannabidiol extracted from cannabis plants may also contain
varying concentrations of THC, which remains a prohibited substance ."
(Note: Policies on hemp and CBD consumption in professional sports
organizations still vary based on the organization).
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.
Latest Clinical Research Updates for Evening Primrose &
Flaxseed (ALA/GLA)
11/18/2021
Can supplementing with
black seed help improve symptoms or prevent severe disease among people with
COVID-19? Find out what research suggests in our answer to the question: What are the health benefits of black cumin seed (black
seed) oil?
11/18/2021
Can supplementing with
black seed help improve symptoms or prevent severe disease among people with
COVID-19? Find out what research suggests in our answer to the question: What are the health benefits of black cumin seed (black
seed) oil?
1/19/2019
Do omega-6 fatty acids
like LA and GLA, found in many seed oils, promote inflammation in the body? No,
and yes, according to the latest findings. Get the details in the Is Omega-6 a Problem? section
of our Omega-3 and -6 Fatty Acid Supplements Review.
Flaxseed Oil for High Blood Pressure?
11/06/2018
Does flaxseed oil (which
is rich in the omega-3 fatty acid ALA) help lower blood pressure in people with
high blood pressure? Learn what a recent study found in the What It Does section
of the Flaxseed Oil Review. (Also see our Top Picks for flaxseed and other seed oils.)
Flaxseed Oil for Improving Cholesterol?
5/10/2015
A recently published
study looked at the metabolic effects of taking daily flaxseed oil on
middle-aged men. It found a possible benefit among those with higher
triglyceride levels, but overall results were not impressive. More about the
study, flaxseed oil, whole flaxseed, and our tests and comparisons of products,
is found in the Flaxseed Oil, Evening Primrose Oil,
Borage Oil, and Black Currant Oil Supplements Review >>