Green Tea Review: Tea Bags, Loose Tea, Matcha Powders, and Supplements

Disturbing Findings for Some Major Brands of Green Tea. See the Test Results and Our Top Picks for Green Tea.

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

Last Updated: 06/22/2021 | Initially Posted: 05/22/2021

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Table of Contents

Summary

· What is green tea? Green tea is made by lightly steaming freshly cut leaves of Camellia sinensis. It is higher in catechins (polyphenols) such as EGCG than black tea. It is sold in many forms such as tea bags, loose teas, matcha powders, bottled teas, and as supplements containing extracts with high concentrations of catechins. Green tea also contains caffeine — about half as much per cup as in coffee. (See What It Is).

· Health benefits of green tea: Health benefits are generally associated with catechins in green tea, most notably EGCG. Benefits include a modest reduction in LDL cholesterol, reduced growth of uterine fibroids and associations with lower risks of cardiovascular disease, certain cancers and type 2 diabetes. These benefits are generally associated with consumption of 3 or more cups per day. Studies with green tea supplements typically provide 200 mg to 300 mg per day. The evidence regarding weight loss and memory benefits is mixed and may relate to the caffeine in green tea. (See What It Does).

· What did CL's tests of green tea products find? Our tests (see What CL Found) found shockingly little EGCG (0.64 mg to 7.6 mg) per cup in four brands of brewable teas (tea bags or loose tea), but much higher amounts (up to 90.8 mg) in several others. Supplements provided 26.4 mg to 250 mg of EGCG per serving. Matcha powders provided about 100 to 150 mg of EGCG per teaspoon (2 grams).

· Which is the best green tea? Our Top Pick among green tea in tea bags stood out for having excellent flavor and providing one of the highest amounts of EGCG at modest cost. Our Top Pick for matcha costs just 1/3 the price of a nearly identical matcha powder and provides 50% more EGCG. We chose both a low-dose and a high-dose Top Pick among green tea supplements.

· Although green tea leaves can accumulate toxic lead, none of the products were found to provide significant amounts of lead.

· Green tea safety, side effects, and drug interactions: Green tea can interfere with a range of drugs. Liver toxicity is a concern with high doses of EGCG from green tea supplements, particularly if not consumed with food. Avoid excessive green tea when pregnant. Excessive tea consumption can make bones and teeth brittle. Don't drink very hot tea due to an association with gastric cancer. (See Concerns and Cautions).

Update

Harney & Sons Japanese Sencha (6/22/21): A CL member contacted Harney & Sons about this product which was Not Approved in this Review because tea brewed from it provided an extremely small amount (6.4 mg) of EGCG which, we as we note in the Review, could potentially be due to the quality of the tea or to the tea bag material itself interacting with the EGCG. Harney's tea bag seems to be nylon, which we know can potentially bind EGCG. The low amount was confirmed in a second laboratory.

Rather than conduct a test similar to ours of tea brewed from its product, Harney & Sons forwarded information only about the sencha tea leaf itself, providing a certificate of analysis from Japan showing that testing on May 28, 2021 of a 2-gram sample of cut sencha leaf (similar to the amount in a tea bag) contained 134 mg of EGCG and a total of 260 mg of catechins. It is possible that this is correct for that sample. However, it does not show the amount a consumer would obtain from tea brewed from Harney & Sons Japanese Sencha. The test method was not furnished, but we assume that it involved extraction with a combination of water and alcohol, which would not resemble the type of extraction that occurs with brewing a tea bag in water. It is also not clear if the sample of sencha was obtained from a Harney & Sons tea bag or even from tea used in the lot we tested (which has a "Best By" date of "11 05 22").

Harney & Sons' representative, Courtney Cozart, wrote in an accompanying email (6/18/21): "The lab we contacted did note that the Consumer Lab testing method was flawed, as they were comparing brewed tea rather than the content in the dry tea leaves, and brewed tea will show different results based on water temperature, steeping time, mineral content, and other factors that are difficult to control."

We disagree with the assertion that our method was flawed. In fact, our method indicates a research approach that is consumer-focused and is the same approach used by other consumer-focused researchers in published studies cited in our Review.

We would encourage Harney & Sons to investigate why so little EGCG seems to be provided by their product. Per our policy, we retain an unopened sample of the product and would be happy to provide it to a mutually acceptable lab to conduct such testing, so long as Harney & Sons agrees to release the findings to the public, which we would also do.

What It Is:

Green tea is made from the plant Camellia sinensis. It contains polyphenolic compounds called catechins that in, test tube studies, show antioxidant, anticarcinogenic, antitumorigenic, and anti-microbial properties. Green and black teas are both made from the same plant, but green tea is made by lightly steaming freshly cut leaves, while black tea is fermented and has lower amounts of catechins. The main catechin found in green tea is epigallocatechin gallate (EGCG). Green tea also naturally contains caffeine — although somewhat less than black tea and much less than coffee. Green tea supplements typically contain dry or liquid extracts of green tea or green tea herb powder.

What It Does:

Green tea as a drink or extract has been promoted for a variety of health benefits, but the most common are cardiovascular disease, cancer, diabetes and weight loss. Much of the research behind green tea, however, is not from clinical trials designed to establish cause and effect relationships, but from studies of populations (typically in Asia) where the use of green tea has been associated with certain health outcomes.

Cardiovascular Disease:
Population studies have found routine green tea consumption — typically 5 or more cups per day — to be associated with about a 20% reduction in the risk of coronary artery disease (Wang, Am J Clin Nutr 2011) as well as a reduced risk of death caused by heart disease (Kuriyama, JAMA 2006). A later study in China that followed over 100,000 men and women (ages 35 - 59) for approximately seven years produced similar findings but at somewhat lower tea consumption: Regular tea drinkers (> 3 cups of tea per week) had a 20% decreased risk of cardiovascular events compared to those who did not drink tea or drank tea less frequently (< 3 cups of tea per week), as well as greater disease-free years and life expectancy, even after adjusting for lifestyle factors such as fruit and vegetable consumption and physical activity. However, this was true only for those who drank green tea and certain other types of Camellia sinensis tea (e.g. pu'er, oolong). Drinking black tea was not associated with a reduced risk of cardiovascular events or increased life expectancy (Wang, Eur J Epidemiol 2020). Although not as dramatic in its findings, another study in China that followed more than one hundred thousand men for an average of 11 years found that, compared to non-green tea drinkers, regular green tea drinkers had significantly lower rates of death (about 5% lower if drinking as much as 5 cups per day, and 11% lower if drinking more), as well as lower rates of death from cardiovascular disease (9% lower for those drinking as much as 5 cups per day and 14% lower if drinking more) (Liu, Eur J Edidemiol 2016). (Note: Tea use was reported in the study in grams of tea: 2 grams equals about 1 cup.)

Drinking green tea helped lower blood pressure as well as reverse left ventricular hypertrophy among people who drank green tea for four months in a study in Egypt. The study participants, all of whom had high blood pressure and were in their early 50s, drank 4 cups daily of either Lipton decaffeinated green tea (each cup made by brewing 1 teabag for 1 minute with constant movement in 8 ounces of boiled water, with no added sugar or milk; each teabag contained 2 grams of green tea providing about 130 mg of total catechins -- similar to levels in several teas in this Review, below). Systolic, diastolic, and pulse pressures decreased by approximately 6%, 4-5%, and 8-9%, respectively with green tea, as opposed to smaller and non-statistically significant decreases with just hot water. Measurements returned to baseline after discontinuation of green tea. The percentage of participants with left ventricular hypertrophy (an enlargement of the heart muscle associated with high blood pressure), fell by 60% with green tea, but increased after discontinuation of green tea. During the study, participants continued their normal medications (Al-Shafei, Physiologic Rep 2019).

An analysis of 14 studies showed that drinking green tea or taking green tea extract reduced total cholesterol by 7.2 mg/dL, including a 2.2 mg/dL decrease in low-density lipoprotein (LDL, "bad cholesterol"), compared to a control group. Green tea did not significantly change levels of high-density lipoprotein (HDL, "good cholesterol") (Zheng, Am J Clin Nutr 2011).

Another analysis of 31 studies (12 of which were included in the previously described analysis) of 3 weeks to one year in duration found that drinking green tea or taking green tea extract modestly reduced total cholesterol by 4.66 mg/dL and LDL cholesterol by 4.55 mg/dL compared to a control group. Both green tea beverage and extract reduced total cholesterol, but only green tea extract reduced LDL cholesterol. Both caffeinated and decaffeinated green tea reduced total cholesterol by about 4.3 mg/dL, but only decaffeinated green tea reduced LDL cholesterol. Green tea did not significantly reduce triglycerides or increase HDL cholesterol, regardless of type of green tea or caffeine content. The average daily intake of green tea catechins was 631 mg (range 80 to 2489 mg/day) (Xu, Nutr J 2020).

Population studies have also found the consumption of 3 or more cups of green tea to be associated with a 21% reduction in the risk of ischemic stroke compared to consumption of less than one cup per day (Arab, Stroke 2009). Similarly, a study in Japan found the risk of stroke among Japanese adults (ages 45 to 74) to be 14% and 20% lower, respectively, for those with daily consumption of 2-3 cups and 4 or more cups, compared to those who seldom drank green tea (Kokubo, Stroke 2013). Interestingly, a study of over 400,000 men and women in China also found green tea consumption associated with a decreased risk of stroke, but only in men -- among whom the risk of stroke (ischemic and hemorrhagic stroke) was 11% lower for those who consumed green tea daily compared to those who did not consume green tea. Risk of stroke also decreased in men with duration (years) of tea consumption (Tian, Am J Clin Nutr 2019).

Cancer Prevention:
Test tube and animal studies hint that tea constituents might help prevent cancers of the stomach, lung, esophagus, duodenum, pancreas, liver, breast, and colon. The majority of studies have examined the effects of drinking brewed tea, rather than the effects of taking green tea supplements.

Studies in people have not always found green tea to reduce the risk of cancer, but those that have typically involved a larger number of cups per day (at least 2), and, regarding gastric cancer specifically, it may be preferable to drink green tea that is not very hot.

An analysis of 51 studies, most of which were population studies, found no consistent association between green tea consumption and gastric, colon, esophageal, pancreatic, or bladder cancer risk, although some studies found an association between green tea consumption and a reduced risk of liver cancer and ovarian cancer (Boehm, Cochrane Database Syst Rev 2009). In fact, a later analysis of studies conducted found that drinking one cup of green tea per day was associated with a 31% reduction in the risk of ovarian cancer; drinking one cup of black tea per day was associated with a more modest 8% reduction in risk. Drinking more than 1.7 cups of green tea per day did not further reduce the risk (Zhang, Carcinogenesis 2018).

Despite some earlier equivocal results, an analysis of studies in 2017 suggested that long-term and high-dose consumption of green tea may be associated with a reduced risk of gastric cancer, so long as the tea was cool or warm (up to 46.9° C/116° F). Drinking very hot green tea (more than 54.9° C/130° F), however, may increase the risk of gastric cancer -- in fact, the cancer risk was 7.6 times higher with very hot vs. cool green tea (Huang, Pub Health Nutr 2017).

Drinking green tea, particularly when very hot, may increase the risk of esophageal cancer, according to a study of men in China. Compared to men who did not drink green tea, those who drank green tea had 1.5 times the risk of developing esophageal cancer, and the risk was 2.5 times that of non-drinkers if the tea was consumed when very hot (i.e., within one minute after pouring boiling water over tea leaves) (Yang, Clin Epidemiol 2018). Similarly, a 10-year study in Iran found the risk of esophageal cancer among drinkers of "very hot" tea was 2.4 times that of drinkers of "cold/lukewarm" tea. There was little difference in risk between drinkers of "hot" tea and "cold/lukewarm" tea. The results indicate that waiting 4 or 5 minutes for tea to cool was sufficient to avoid the increased risk of cancer (Islami, Int J Cancer 2019).

A large study of men in China (Liu, Eur J Epidemiol 2016 - described further above) found the risk of death from cancer to be lower among regular drinkers of green tea than among non-drinkers, with those consuming more than 5 cups per day having a 21% lower death rate.

A study in South Korea among 143 men and women (average age 59) who had recently had polyps (growths which sometimes develop into colon cancer) removed from their colons found that those who took two tablets of green tea extract twice a day with meals (totaling of 900 mg of extract, providing 600 mg of catechins of which 200 mg was EGCG) every day for one year following the procedure developed fewer new polyps compared to those who did not take the extract. Among those who took the extract, 28% developed polyps, versus 61% of those who did not take the extract (Shin, Clin Nutr 2017).

Population-based studies have not found drinking green tea to significantly reduce the risk of prostate cancer (Zheng, Nutr Cancer 2011). Some, but not all, clinical studies with green tea extracts have shown some benefits as well as significant reductions in serum PSA levels. For example, a small, but well controlled study in humans using a green tea extract (providing 311 mg of EGCG per day) found that it reduced prostate cancer rates in men who already had pre-cancerous changes in the prostate. After one year, only 3% of the men receiving the supplement developed prostate cancer while 30% of men who received placebo developed prostate cancer (Bettuzzi, Cancer Res 2006; see ConsumerTips™ for dosage used). Another well-controlled, one-year study in another group of men with pre-cancerous prostate lesions used a different green tea exact (providing 400 mg of EGCG per day). This study, funded by the National Institutes of Health, showed a lower incidence of prostate cancer among those taking the extract (10.2% developed cancer) than those taking placebo (18.8% developed cancer) but the results were not statistically significant — partly due to the small size of the study. However, among those taking the extract, there were statistically significant decreases in serum levels of PSA (a prostate cancer marker) and in the diagnosis of ASAP (lesions which may be pre-cancerous) (Kumar, Canc Prev Res 2015). Similarly, a small study among 60 men in Italy with pre-cancerous changes in the prostate found that 600 mg of green tea catechins (specific amount of EGCG not listed) taken daily for one year significantly lowered average PSA levels compared to placebo; however, it did not decrease the incidence of prostate cancer which, over one year, was 18% in both groups (Micali, Arch Ital Urol Androl 2017).

Drinking green tea has been associated with a reduced risk of breast cancer and its recurrence. A study in the U.S. that followed over 45,000 women (average age 55) for approximately eight years found the risk of breast cancer to be 18% lower among those who consumed five or more cups of green tea per week compared to those who never consumed green tea. A somewhat lower risk reduction of 12% was associated with drinking five or more cups of black tea per week (Zhang, Int J Cancer 2019). An analysis of 9 population studies found drinking more than 3 cups of green tea per day was associated with a 27% reduced risk of breast cancer recurrence (Ogunleye, Breast Cancer Res Treat 2010). However, a cause-and-effect relationship between green tea use and lower risk of breast cancer has not yet been shown. In fact, a large, one-year clinical trial of high-dose, decaffeinated green tea extract (1,315 mg total catechins daily providing 843 mg of EGCG, taken as 2 pills with breakfast and 2 pills with dinner) given to healthy postmenopausal women in Minnesota ages 50 to 70 at high risk for breast cancer (based on breast density) found no effect on breast density, except for women ages 50-55 who experienced a slight reduction relative to placebo (Samavat, Cancer Prev Res 2017). The same study found that, relative to placebo, green tea extract increased levels of the sex steroid hormone estradiol. This is the opposite of what has been shown in studies with brewed green tea and is of concern because higher levels of estrogens are linked to increased risk of breast cancer in postmenopausal women. Women assigned to the extract were also more likely to experience increases in liver enzymes, suggesting an adverse effect on the liver (see discussion in Concerns and Cautions) (Samavat, J Nutr 2019).

An analysis of 12 population studies found that dinking 2 cups daily was associated with an 18% reduction in the risk of lung cancer compared to consuming less than a cup per day (Tang, Lung Cancer 2009).

Preliminary laboratory evidence suggested that the green tea catechin, EGCG, may help prevent skin cancer if applied directly to the skin. However, a double-blind, placebo controlled study failed to find that a combination of oral and topical green tea extracts reduced signs of precancerous sun-damage in skin.

Other ingredients with potential benefit in cancer include vitamin E, folate, garlic, selenium, soy isoflavones and other isoflavones, indole-3-carbinol (I3C), diindolylmethane (DIM), vitamin C and vitamin D.

Fibroids:
Laboratory research has suggested a role of green tea extract in shrinking uterine fibroids, which are non-cancerous tumors of the uterine wall affecting up to 70% of reproductive-age women and which may cause pelvic pain. Based on these findings, a study was conducted in 33 women ages 18 to 50 years with uterine fibroids. The women were given 800 mg of green tea extract (45% EGCG) or a placebo, taken after meals, daily for 4 months. By the end of the study, fibroid size (volume) was reduced by 32.6% among women receiving the extract, while it increased 24.3% in the placebo group. Treatment also significantly reduced the severity of symptoms (such as pelvic pain), as well as anemia (which can occur with fibroids). No adverse effects were observed (Roshdy, Int J Wom Health 2013). While these results seem promising, taking a green tea extract is not advisable for women who may be conceiving or are pregnant, due to increased risk of birth defects (see Concerns and Cautions).

Blood Sugar Control/Diabetes:
Green tea polyphenols, particularly catechins, may decrease fasting and postprandial ("after a meal") blood sugar levels, and timing may matter. A study among 17 healthy young men in Japan found that consuming brewed green tea (12 fluid ounces providing 615 mg total catechins -- including 135 mg EGCG -- and 85 mg caffeine) with an evening meal resulted in significantly smaller increases in blood sugar levels one hour later compared to drinking 12 fluid ounces of hot water containing 80 mg of caffeine with the meal. However, there was no significant effect compared to the control drink when the experiment was repeated with the same meal in the morning. The researchers noted that blood sugar levels tend to rise in the evening, possibly explaining the greater blunting effect of green tea consumed at that time of day (Takahashi, J Nutr Biochem 2019).

An analysis of 20 population studies shows that drinking 3 or more cups of black or green tea daily is associated with a 16% reduced risk of developing type 2 diabetes (Huxley, Arch Intern Med 2009).

Weight Loss:
While some studies have found green tea to modestly aid in weight loss and protect against weight gain, not all studies have found a benefit, and some researchers have proposed that weight loss associated with green tea could be largely attributed to its caffeine content (as caffeine can reduce appetite and is a key component other herbal weight loss supplements) (Phung, Am J Clin Nutr 2010). However, one study of a caffeine-rich green tea extract supplement found no weight loss benefit. In the study, normal weight, overweight, and obese men and women who took 9 capsules daily of green tea extract (providing between 280 — 540 mg caffeine and a minimum of 560 mg EGCG per day) for 3 months had no significant change in body weight compared to those who took a placebo (Janssens, J Nutr 2015). The study also investigated whether the extract reduced the amount of fat men and women absorbed from their food (another proposed effect of green tea catechins), but no significant difference in absorption was found. A limitation of this study was that the researchers were aware who received the extract and who received the placebo, although the study was not funded by the manufacturer of the extract.

It has also been suggested that green tea catechins may help with weight management by inhibiting starch digestion and absorption (by inhibiting digestive enzymes). This theory was tested in young adults fed corn flakes while being given a green tea extract or a placebo. The carbohydrates in the corn flakes contained a special form of carbon and the amount of carbohydrates absorbed from the corn flakes was determined by the measurement of this carbon in their breath for up to 4 hours after the meal. Based on this analysis, the green tea extract (4 grams containing 257.6 mg of EGCG) reduced the amount of carbohydrate absorption by 29% (Lochocka, Nature Sci Reports 2015).

Studies using decaffeinated green tea extract have generally not shown a significant benefit. One study involved obese young women in Spain who were put on a low-calorie diet and given either a green tea extract or a placebo, three times a day with meals. The extract provided approximately 300 mg of EGCG daily. After 12 weeks, both groups lost approximately equal amounts of weight and fat (Mielgo-Ayuso Br J Nutr 2014). A more recent 12-week study gave obese women in Taiwan an even higher daily amount of EGCG (856.8 mg per day from 3 capsules, each taken 30 minutes after a meal). Although weight decreased in the treated group by 2.4 lbs (and the researchers touted this in their conclusion), weight also decreased among those given placebo containing just cellulose and the treatment was actually not significantly more effective than the placebo (Chen, Clin Nutr 2015). Although no adverse effects were reported, liver enzymes increased in the treatment group, suggesting the potential for liver injury — a known concern with green tea extracts (see Concerns and Cautions).

On the other hand, a study in sedentary overweight and obese men in England given decaffeinated green tea extract for 6 weeks showed weight loss of 1.4 lbs while men given placebo gained 1.2 lbs despite similar increases in caloric intake in both groups (Brown, Br J Nutr 2011). This study used 530 mg of extract in capsules given twice daily (providing 432 mg EGCG/day) — one capsule was taken an hour before breakfast and the other was taken an hour before dinner. The amount of catechins in this daily dosage is comparable to that in about six to eight cups of moderate strength green tea.

Memory and Cognition:
Green tea consumption has been associated with a lower risk of cognitive decline in older adults, although clinical trials in which people are given green tea have shown little or only very modest benefit. Green tea extracts (such as in capsules) do not appear to improve cognition in older people, although they may cause short-term improvement in attention (possibly due to caffeine).

Drinkable tea:
Higher consumption of green tea has been associated with lower prevalence of cognitive impairment in older adults (Kuriyama, Am J Clin Nutr 2006).

A 4-year study of 957 older Chinese men and women (average age 64) with normal cognitive function found that regular consumption of at least 1 cup of green tea per week (and, more typically, 1+ cups per day) lowered the risk of cognitive decline by 57% compared to non-regular tea drinkers. The risk was also reduced by 47% among black and/or oolong tea drinkers. Interestingly, people who drank a "medium" amount of tea (3 to 4 cups daily, including all types of tea) had a 64% reduction in risk, which was even more than for those who consumed a "high" amount of tea (5 or more cups daily), who had a 54% reduction, while "low" consumers (1 to 2 cups daily) had a 25% reduction. Among people at increased risk of developing Alzheimer's disease due to having the ApoE4 gene, regular consumption of tea (green, black or oolong) reduced the risk of cognitive decline by 86% (Feng, J Nutr Health Aging 2016). Similarly, a study that followed older people in Japan for 5.3 years found the risk of experiencing cognitive decline was 30% lower if a person consumed green tea once a day as compared to less than once a day. Drinking green tea more often conferred no significant additional benefit (Shirai, Public Health Nutr 2019).

A small study among healthy young men and women (average age 25) in the Netherlands found that 4 grams of matcha tea powder (containing 280 mg EGCG, 67 mg L-theanine and 136 mg caffeine) consumed as brewed tea (2 cups) or as a matcha tea bar significantly increased certain aspects of cognition (attention and response time) one hour after consumption compared to placebo. There was no significant improvement in memory or other measures of cognition, or mood. This dose of matcha provides 136 mg of caffeine — more caffeine than the average cup of coffee — and, as the researchers noted, caffeine alone has been shown to have similar effects on cognition. (You can see the amounts of caffeine and EGCG we found in matcha teas in the Results table below). (Dietz, Food Res Int 2017).

Green tea extract:
A study in Japan suggested that green tea extract does not improve most measures of cognitive function in otherwise healthy, older adults. The randomized, placebo-controlled study among 47 healthy, older, adults (average age 58) found that taking three capsules of green tea extract (THEA-FLAN 90S, Ito-en Ltd) providing 336.4 mg of catechins (including 216.9 mg of EGCG) and 2.7 mg of caffeine once daily after breakfast for 12 weeks did not improve visual or verbal memory, attention, facial expression recognition, visual processing, or motor function compared to placebo, although people given the extract did show improvement on a working memory task (Baba, Molecules 2020). The study was sponsored by the manufacturer of the green tea extract, and all but one of the investigators were affiliated with the company.

Another study in Japan also suggested that green tea may not help to improve cognition in people with more severe forms of cognitive impairment. In the study, elderly men and women (average age 84) with dementia (Alzheimer's disease, vascular dementia or Lewy-body dementia) who consumed 2 grams of green tea extract powder daily (providing 220 mg of total catechins including 88 mg of EGCG — equivalent to approximately 2-4 cups of bottled or brewed green tea) found there was no improvement in cognitive function after one year compared to placebo (Yamada, Nutr J 2016).

A study of green tea extract with added l-theanine, suggested that consumption improves memory and attention in subjects with mild cognitive impairments (Park, J Med Food 2011).

Some excitement was generated by a Swiss study in 2014 reported by some news sources as showing that green tea extract helped improve working memory (i.e., short term storage and retrieval of information). Unfortunately, these accounts were exaggerated and misleading. This small study evaluated brain activity in young, healthy men after consuming a drink containing green tea extract or one without the extract (Schmidt, Psychopharm 2014). Although there was a strong trend toward improved task performance with the extract and enhanced parieto-frontal connectivity within the brain, the memory improvement was not statistically significant. In addition, the dose of green tea extract was enormous — 27,500 milligrams, which is equivalent to about 80 cups of green tea or about 50 doses of a typical green tea extract supplement. Although the amount of EGCG was not noted in the study, the drink contained approximately 13,750 grams of polyphenols and roughly half that would be expected to be EGCG, or about 7,000 mg — also an enormous amount. Most notably, the amount of caffeine in the supplement was reported to be approximately 5 to 10% of the extract. This equates to 1,375 mg to 2,750 mg of caffeine — the equivalent of drinking about 14 to 28 cups of coffee at one time. The caffeine, itself, may have played an important role in the results. Such as dose of green tea extract would not be recommended and, interestingly, the study failed to mention whether adverse effects occurred.

Flu:
In laboratory and animal studies, green tea catechins have been shown to have anti-viral effects. There is some preliminary evidence that drinking green tea may decrease the risk of flu infection. A study among children ages 6 to 13 in Japan found that drinking between one and five cups of green tea daily between the months of November and February was associated with a decreased risk of flu (Park, J Nutr 2011). Some, but not all studies have found that gargling with green tea helps prevent infection with the flu. A review of five clinical studies that investigated the effects of gargling with tea (bottled green tea, or green tea extract or black tea extract solution — typically 2 to 3 times per day) found that doing so reduced the risk of flu infection by 30% compared to gargling with water or not gargling (Kazuki, BMC Public Health 2016).

The evidence for green tea supplements is less clear. A study of 197 healthcare workers in Japan during flu season (November through April) found significantly fewer incidents of influenza among that those who took a combination of green tea catechins and L-theanine (Suntheanine, Taiyo Kagaku Co — providing a daily total of 378 mg green tea catechins (including 270 mg EGCG) and 210 mg of theanine). During the five month period, 4.1% of those who took the green tea/theanine combination were diagnosed with the flu (based on symptoms), compared to 13.1% of the placebo group (Matsumoto, BMC Complement Altern Med 2011). However, the incidence of flu infection as confirmed by laboratory testing was not significantly different between the two groups.

Dental health:
Polyphenols in green tea may inhibit the build-up of dental plaque by preventing oral bacteria from feeding on sugar in the mouth (Koo, Eur J Pharmacol 2004). In addition, one small clinical study found that when adults rinsed for one minute with 10 mL (about 2 teaspoons) of either brewed green tea, chlorhexidine (a prescription antibacterial mouthwash) or water, those who rinsed with green tea or chlorhexidine had, respectively, 16% and 17% lower counts of decay-causing bacteria (Streptococcus mutans), than before rinsing (Neturi, J Clin Diagn Res 2014). Those who rinsed with water had no significant change in bacterial counts. The green tea was prepared with 2 grams of fresh green tea packed in a tea bag (see the Results table below for brewable green teas providing similar amounts) and steeped in 100 ml (about 3. 5 oz) warm water for 5 minutes; the amount of polyphenols in this preparation was not indicated. The study also did not indicate the temperature of rinses, which could have affected results if the tea was warm but the water was not.

Prebiotic effect:
Polyphenols in green tea may have a prebiotic effect, stimulating the growth of beneficial bacteria in the gut and inhibiting the growth of pathogenic bacteria, such as Clostridium species (Liu, J Agric Food Chem 2018). This has been demonstrated in animal studies and in a human study in which people who did not normally consume green tea drank about four cups of green tea daily (1,000 mL in total). After 10 days, the proportion of Bifidobacterium species (thought to be beneficial) tended to increase (Jin, Microbio Immunol 2012.) Interestingly, although green tea polyphenols are typically not well absorbed in the gut, bacteria can transform them into compounds that can be readily absorbed. However, a study of green tea extract given to people as capsules (providing at least 560 mg of EGCG daily) did not show any effect on bacterial species in the gut (Janssens, PLoS One 2016).

Quality Concerns and Tests Performed:

Neither the FDA nor any other federal or state agency routinely tests green tea products for quality prior to sale. However, quality issues can include the following:

· Labeled Amount: Does the product really contain the labeled amount of ingredient? Too little may not work. Too much may cause toxicity (see Cautions and Concerns). Confirming the amount of green tea in supplements involves measuring green tea catechins, including EGCG. (Some products list amounts of a broader group of compounds, polyphenols, but tests for polyphenols are less specific for green tea.)

· Purity: Is the product free of lead and other heavy metals that can accumulate in green tea leaves? It is well established that tea leaves from particular areas (such as certain regions of China) contain substantial amounts of lead. In fact, one study found that 24% of green tea leaf samples in China exceeded 2 mcg of lead per gram (i.e., 3 mcg of lead per 1.5 gram), and even higher percentages of scented tea (32%), black tea (59%), and oolong tea (53%) exceeded this level. In comparison, a study of green teas produced in Japan found no sample to exceed this level (Han, Environmental Pollution, 2006). The lead in green tea leaf is believed to come from industrial pollution of the soil and air, proximity to roadways (due to past use of leaded gasoline), and processing techniques. Most of the lead is contained within the leaves. Younger leaves, such as those used to make green tea, tend to contain less lead than older leaves, such as those used to make black and oolong tea. (Pesticides have also been reported at trace levels in green tea, although not in amounts that would elicit adverse health effects (CBC, 2014). Tests of matcha powders by ConsumerLab in 2015 found no significant pesticide contamination.)

· Caffeine: While caffeine occurs naturally in green tea, levels may vary widely among products and these amounts are often not disclosed on labels. Because of caffeine's potential side effects and potential for increasing the side effects of other stimulants, it is useful to know the amount of caffeine in a daily dose.

ConsumerLab.com, as part of its mission to independently evaluate products that affect health, wellness, and nutrition, purchased and tested commonly available green tea products, including supplements, brewable tea products (tea bags and loose tea), and matcha powders. These were tested to determine their EGCG and total catechin content and level of contamination with lead, cadmium, and arsenic (see Testing Methods and Passing Score). The amount of caffeine in each product was also determined and compared to the listed amount (if labeled). ConsumerLab.com typically tests supplements in tablet form for their ability to properly break apart (disintegrate) but none of the supplements in this review were tablets — all were capsules.

What CL Found and Top Picks:

EGCG and Catechins
We discovered a disturbingly large range of EGCG per serving in the tested products. Most shocking was the extremely small amount of EGCG in some brewable tea (tea bags). As shown below, most brewable teas provided at least 40 mg of EGCG, but several provided less than 10 mg. As a result, four brewable green teas were Not Approved. One powdered product could not be approved due to inconsistent labeling.

Among supplements (shown below), some were found to be very high potency (over 200 mg of EGCG per serving), while others contained only the amount of EGCG expected from about a half-cup of green tea.

Contamination from the heavy metals, lead, cadmium and arsenic was not found to be a problem with any of the products.

Cost
Due to a combination of the large range of EGCG found in products and the price per serving of products (ranging from 8 cents to $1.21— as shown in the results tables), the cost to obtain 50 mg of EGCG (an average amount in a cup of good quality green tea) ranged from 6 cents to $9 among brewable teas and powders and from 1 cent to 84 cents among green tea supplements.

Brewable Green Tea — Tea bags and Loose tea:
Among the 13 brewable green tea products selected for review, nine were Approved for quality, and their amounts of EGCG per serving (typically one teabag, containing about 1.4 to 2.1 grams of tea) ranged from 43 mg to 90 mg. Among these, a good cup of tea, with plenty of EGCG, could be had for as little as 9 to 13 cents from Prince of Peace, Trade Joe's, Twinings, and Newman's Own.

However, the following four products were Not Approved because they provided very low amounts of EGCG (less than 20 mg per serving), with amounts ranging from only 0.64 mg to 7.6 mg.

These low amounts suggest questionable value from a therapeutic perspective as well as poor quality green tea. The lowest amount of EGCG previously found by ConsumerLab in brewable green teas (in 2018) was 26.9 mg in Kirkland Signature Green Tea — a blend of sencha and matcha, and 30.2 mg in Salada Decaffeinated Green Tea. But those are respectable amounts compared to what we found this year in these four products:

· Bigelow® Green Tea — Decaffeinated (12 cents/bag) — Provided a measly 0.64 mg of EGCG per serving (13.7 mg of catechins). When we tested the same product in 2018, it provided 37 mg of EGCG (95.4 mg of catechins). In contrast, Bigelow's non-decaffeinated "Premium" green tea (16 cents/bag), tested in the current review, provided a healthy 43 mg dose of EGCG and 113.4 mg of catechins.

· Choice Organics Japanese Green (42 cents/bag) — Provided only 3.6 mg of EGCG (49.7 mg of catechins).

· Harney & Sons Japanese Sencha (56 cents/bag) — Provided only 6.4 mg of EGCG (53.2 mg of catechins)

· Lipton Green Tea — Decaffeinated (8 cents/bag) — Provided only 7.6 mg of EGCG (18.6 mg of catechins). In contrast, Lipton's non-decaffeinated, "Pure" green tea (19 cents/bag), provided a whopping 90.8 mg of EGCG and 202.3 mg of catechins, which is even a bit more than when we tested it in 2018 and found 79 mg EGCG and 150.7 mg of catechins.

In addition, Vahdam Teas 100% Pure Green Tea (29 cents/teaspoon), a loose tea, provided just 22.5 mg of EGCG per teaspoon (2 grams) of tea, which is relatively low, although above our cut-off for Approval.

It is interesting to note that for both Lipton and Bigelow, their slightly more expensive, non-decaffeinated, teas had much higher levels of EGCG than their inexpensive decaffeinated teas. At the same time, the most expensive teas in the review (Harney & Sons and Choice) had much lower amounts of EGCG than more moderately priced teas.

We took great efforts to apply a testing method that would allow us to see the full amount of EGCG from these teas when brewed in hot water. The teas were brewed in deionized (mineral free) water to avoid reductions in catechins that can occur with tap water. Although some test methods involve filtering or centrifuging the brewed tea before being chemically analyzed, we avoided both steps as they can potentially remove catechins. We repeated the tests in two labs. We know that this method works based results with other teas.

So why were EGCG levels so low for these teas? It is unclear. One possible explanation is that some bags may have been made of newer plant-based materials (such as hemp, corn starch, and abaca) that may, inadvertently, bind to or block EGCG from exiting the bag. Other possibilities relate to the quality of the tea leaves. For example, during 2020 there was a tightening in supplies of tea leaves "due to bad weather in some producer countries, labor shortages, port closures and other logistical issues," according to the Wall Street (Journal, Sept. 24, 2020). It is not uncommon during times of low supply and increasing prices that lower quality material finds its way into the market to meet demand.

Top Pick
We found several very good green teas. Among them, our Top Pick for brewable green teas is Trader Joe's Organic Green Tea, which costs 15 cents per tea bag. Although a few cents more than some other Approved teas, it provided significantly more EGCG -- 86.8 mg per serving compared to about 45 to 60 mg in most others. It tied with Prince of Peace as the lowest cost source of EGGC among brewed teas, but Trader Joe's had a true "green tea" taste, aroma, and even color, while others seemed more oxidized, like a blend of green and black tea.

Our previous Top Pick in this category, Lipton Pure Green Tea, had a similar amount of EGCG as Trader Joe's, but it jumped in cost since 2018, rising from 11 cents to 19 cents per tea bag. We also found it to have a faint "fishy" flavor this time around.

If you like a stronger, slightly nutty, flavor, we liked Newman's Own Organic Green Tea, which is only 11 cents per bag, but delivers half the EGCG of Trader Joe's. An even stronger, black-tea-like flavor is found with Numi Organic Tea Gunpowder Green (30 cents per bag). Bigelow Premium Green Tea (16 cents per bag) and Prince of Peace 100% Organic Green Tea (10 cents per bag) remain good options. All of these, however, provide less EGCG than Trader Joe's.

[Although we did not test K-cups this year, in 2018 we found that Celestial Seasonings Green Tea K-cups 9, a combination of green tea and white tea) provided only 32.4 mg of EGCG per K-cup, despite containing about twice as much tea leaf (3.4 grams) as most tea bags (usually less than 2 grams). We found Celestial to be a very expensive way to get EGCG.]

None of the brewed teas contained a significant amount of lead or other heavy metals (cadmium and arsenic). However, be aware tea leaves themselves can contain small amounts of lead and they are not intended to be directly consumed.

Matcha Green Tea and Other Powders
Another way of drinking green tea is as matcha — a fine, bright green powder made from young tea leaves grown in shade (which may increase chlorophyll production) with stems and veins removed. Matcha powder is mixed with hot, but not boiling, water, and whisked, typically with a wooden chasen, into a slightly frothy smooth drink. Matcha is generally more expensive that brewable green tea, somewhat more time-consuming to prepare, and, traditionally, was reserved for tea ceremonies rather than daily consumption — and there has been little clinical research in humans with matcha.

Matcha powder is also used in foods and drinks — adding green tea flavor and color, as well as EGCG and other catechins — although a "culinary grade" matcha is typically used, which may not have as delicate a flavor as ceremonial matcha used as tea.

From a dietary standpoint, what sets matcha apart from brewed green tea is that you are consuming the leaf as opposed to discarding it. As a result you are getting ALL the EGCG in powder, in contrast to brewed tea in which some portion of those remain within the tea bag and tea leaves. Consequently, as shown in the first graph above, based on 2 gram (about 1 teaspoon of powder) serving, the two matcha powders that we tested (both of which were culinary grade), provided much higher amounts of EGCG than the brewable teas, yielding 158 mg from SuperFoods Matcha Green Tea Powder and 102.4 mg from Jade Leaf Organics Japanese Matcha.

Top Pick
These two culinary matcha powders taste about the same when mixed in water -- although Jade Leaf seemed to have a slightly smoother mouth feel. However, SuperFoods provided more EGCG and is a much better value, costing 18 cents per teaspoon versus 40 cents for Jade Leaf. As a result, SuperFoods Matcha Green Tea Powder is our Top Choice for matcha green tea — just as it was in 2018.

We did not test ceremonial matcha green tea this year. In 2018, our Top Pick for ceremonial matcha was Organic Kenko Tea Matcha which had 118.8 mg of EGCG per 2-gram serving, double the amount we found in Kiss Me Organics Organic Matcha.

Fortunately, contamination with lead and other heavy metals (cadmium and arsenic) was not found to be a problem with any of these matcha green teas, which is consistent with tests in earlier years by ConsumerLab.

A novel product that we included in this year's review is Pique Tea Crystals -- Jasmine, which was suggested by some of our readers. It comes in small packets of powder, and the powder dissolves quickly into hot water to make a fragrant, jasmine-scented tea. It was found to provide about the same amount of EGCG (55.1 mg) as a cup of good green tea. However, it is very expensive at $1.21 per packet. Information about the product is inconsistent: The packets state "Jasmine Green" but the only ingredient listed is "Organic jasmine tea." Only on the Pique website is it stated that it includes green tea, noting that it contains "Superior Japanese green tea infused 5 times with fresh Jasmine petals." We're not sure exactly what to make of this product, but if you love jasmine, want a decent amount of EGCG, like the convenience of a powder, and don't mind paying a lot for all this, you can give this a try. It also has a decent amount of caffeine (47.2 mg per packet). It could not be Approved due to labeling inconsistency.

Green Tea Supplements
All three of the green tea supplements selected by CL for review passed quality testing, as did three additional supplements evaluated through ConsumerLab.com's voluntary Quality Certification Program (each of which is identified with a CL icon by its name).

Although all of the supplements were made from green tea "extracts," it is important to understand that some extracts are much more concentrated than others. This explains why four of these (H-E-B, Nature's Bounty, Puritan's Pride, and Thorne) were found to contain only about 25 to 30 mg of EGCG per serving (one or two capsules), which is about the amount in a half a cup of green tea, while NOW and Vitacost provided about 10 times that amount per capsule, which is more in range with amounts that have been used in clinical trials.

The lower EGCG supplements provided about 25 to 30 mg of caffeine per serving, except for Thorne, which had virtually none. The higher EGCG products contained very little caffeine (1 to 6 mg). As a point of reference, a cup of brewed green tea contains about 40 mg of caffeine -- similar to a can of cola, and a cup of coffee contains about 100 mg of caffeine.

Top Pick
If you want to get about the amount of EGCG and caffeine that you would get from a cup of green tea, but without drinking green tea, you could take a double serving of one of the lower EGCG supplements. The most cost effective, and, hence our Top Pick for a low-dose EGCG supplement is H-E-B Green Tea Extract — 4 capsules would cost 22 cents, around half the price of the next least expensive product.

Our Top Pick for a high-dose EGCG supplement is Vitacost Green Tea Extract, as it costs just 6 cents per capsule. In fact, it is the least expensive source of EGCG of all the products in this review.

Although rare, be aware that cases of liver toxicity have been reported with green tea extracts, particularly those providing hundreds of milligrams per day of EGCG and other catechins, such as more than 800 mg of catechins (which would be expected to contain about 320 mg or more of EGCG) (see Concerns and Cautions).

Test Results by Product:

Listed below are the test results for 22 green tea products: 13 brewable teas, three powders (including two matcha powders), and six supplements. ConsumerLab.com selected 19 of the products. Three supplements (each indicated with a CL flask) were tested at the request of their manufacturers/distributors through ConsumerLab.com's voluntary Quality Certification Program and are included for having passed testing.

Shown for each product are the claimed amounts of green tea as extract or herb as well as green tea components, such as polyphenols, catechins and/or EGCG. Products varied as to which of these amounts they listed, if any. As product quality was judged on catechin and/or EGCG levels, supplements that did not claim any level were held to minimum requirements. Products listed as "Approved" met their label claims and ConsumerLab.com's quality criteria (see Passing Score).

Taste and color descriptions are provided in the 3^rd column for brewable teas and for powders. Cost comparisons are in the 4^th column. The full list of ingredients (including special dietary designations) for each product is available in the final columns.

Results of ConsumerLab.com Testing of Brewable Green Tea And Matcha

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

Approval Statusⓘ

Product Name

Claimed and Found Amounts of Green Tea and Other Componentsⓘ

Heavy Metalsⓘ

Suggested Serving on Label

Color and Taste of Prepared Tea

Cost for Suggested Serving

[Cost Per 50 mg EGCG Found]

Price

Notable Features

Full List of Ingredients

Brewed Tea From Bag:

NOT APPROVED

Low in EGCG

Bigelow® Green Tea - Decaffeinated

Dist. by Bigelow Tea

$ Price Check

1 tea bag
1.4 g

Organic green tea

Decaffeinated (1 mg to 8 mg caffeine)

Foundⓘ
EGCG: 0.64 mg
Catechins: 13.7 mg
Caffeine: 2.6 mg ✔

Metals: Pass (Lead: 0.5 mcg)

Pour over tea bag, steep for 3 minutes (or whatever time you like), remove bag (but no squeezing please!) For Iced Tea by the Glass: Steep a little longer. Pour over ice.

Color & Taste:
Light brown-yellow; Light flavor

$0.12/tea bag

[$9.00]

$4.61/box of 40 tea bags

Decaffeinated. Gluten Free. Non-GMO. Kosher. USDA Organic seal. Quality Assurance International Certified Organic seal.

Carefully Selected Ingredients: Decaffeinated organic green tea.

APPROVED

Bigelow® Premium Green Tea

Dist. by Bigelow Tea

1 tea bag
2 g

Organic green tea

25 mg to 50 mg caffeine

Foundⓘ
EGCG: 43 mg
Catechins: 113.4 mg
Caffeine: 28.8 mg ✔

Metals: Pass (Lead: 0.25 mcg)

Pour over tea bag, steep for 3 minutes (or whatever time you like), remove bag (but no squeezing please!) For Iced Tea by the Glass: Steep a little longer. Pour over ice, more...

$0.16/tea bag

[$0.18]

$24.82/box of 160 tea bags

USDA Organic seal. Gluten Free. Non GMO.

Organic green tea.

NOT APPROVED

Low in EGCG

Choice Organics™ Japanese Green

Dist. by East West Tea Company, LLC

$ Price Check

1 tea bag
1.7 g

Organic green tea

Foundⓘ
EGCG: 3.6 mg
Catechins: 49.7 mg
Caffeine: 29.5 mg

Metals: Pass (Lead: 0.25 mcg)

Give the blend some time to blossom. Bring water just to boiling and steep 2-3 minutes.

Color & Taste:
Yellow-green; Mild green-black tea flavor

$0.42/tea bag

[$5.80]

$6.68/box of 16 tea bags

USDA Organic seal. Non-GMO Project Verified seal. Kosher.

Organic Green Tea.

NOT APPROVED

Low in EGCG

Harney & Sons Japanese Sencha

Dist. by East West Tea Company, LLC

1 tea bag
2.1 g

Japanese green tea

30 mg to 50 mg caffeine

Foundⓘ
EGCG: 6.4 mg
Catechins: 53.2 mg
Caffeine: 46.5 mg ✔

Metals: Pass (Lead: <0.25 mcg)

Begin With Fresh Boiled Water. Pour Boiling Water Over Teabag. Allow Tea To Steep Until Ready.

Color & Taste:
Light green; Grassy flavor

$0.18/tea bag

[$1.40]

$8.99/box of 50 tea bags

Kosher. Halal.

Japanese green tea.

NOT APPROVED

Low in EGCG

Lipton® Green Tea - Decaffeinated

Dist. by Unilever

1 tea bag
1.4 g

Green tea

Decaffeinated (1 mg to 8 mg)

Foundⓘ
EGCG: 7.6 mg
Catechins: 18.6 mg
Caffeine: 1.6 mg ✔

Metals: Pass (Lead: 0.25 mcg)

Color & Taste:
Slightly dark brown; Little flavor, more like black tea

$0.08/tea bag

[$0.52]

$3.19/box of 40 tea bags

Decaffeinated. Kosher. Green tea from Rainforest Alliance Certified™ farms.

Decaffeinated Green Tea.

APPROVED

Lipton™ Pure Green Tea

Dist. by Unilever

1 tea bag
1.4 g

Green tea

Foundⓘ
EGCG: 90.8 mg
Catechins: 202.3 mg
Caffeine: 35 mg

Metals: Pass (Lead: 0.25 mcg)

Boil fresh water and allow to cool for 30 seconds. Pour water over a tea bag and brew 1 - 1.5 minutes.

Color & Taste:
Light brown-yellow; Grassy and slightly fishy

$0.19/tea bag

[$0.11]

$19.20/box of 100 tea bags

Kosher. Rainforest Alliance Certified seal.

Green Tea.

1 tea bag
Calories 0, Total Fat 0 g, Total Carbohydrate 0 g, Protein 0 g.

APPROVED

Newman's Own® Organics Organic Green Tea

Dist. by Harris Tea Company, LLC

1 tea bag
2 g

Organic green tea

Foundⓘ
EGCG: 44.5 mg
Catechins: 121.8 mg
Caffeine: 25.3 mg

Metals: Pass (Lead: 0.5 mcg)

Bring fresh cold water to a rolling boil. Let water cool for 1 minute after boiling. Pour water over one tea bag and steep for 1 - 2 minutes. Remove tea bag, more...

$0.11/tea bag

[$0.12]

$10.99/box of 100 tea bags

USDA Organic seal. Quality Assurance International Certified Organic seal. Kosher.

Organic Green Tea.

APPROVED

Numi® Organic Tea Gunpowder Green

Dist. by Numi, Inc. P.B.C.

$ Price Check

1 tea bag
2.1 g

Fair Trade Certified Organic green tea

Foundⓘ
EGCG: 58.3 mg
Catechins: 119.6 mg
Caffeine: 41 mg

Metals: Pass (Lead: 0.25 mcg)

Steep in freshly boiled water for 2 - 3 minutes.

Color & Taste:
Light brown; Stronger, black-tea-like

$0.30/tea bag

[$0.25]

$16.05/3 boxes of 18 tea bags (54 tea bags total)

USDA Organic seal. Non-GMO Project Verified seal. Kosher. Halal. No "Natural" Flavors Or Fragrances. This product is gluten-free. Fair Trade Certified seal. Partner Carbonfree™ Carbonfund.org seal.

Fair Trade Certified™ organic green tea.

APPROVED

Prince of Peace® 100% Organic Green Tea

Dist. by Prince of Peace Ent., Inc.

$ Price Check

1 tea bag
1.8 g

Organic green tea

20 mg to 30 mg caffeine

Foundⓘ
EGCG: 58.5 mg
Catechins: 128.3 mg
Caffeine: 30 mg ✔

Metals: Pass (Lead: 0.5 mcg)

Place one tea bag in a 6 fl. oz. (177 ml) cup, add hot water and let it steep for 3 - 5 minutes before drinking.

Color & Taste:
Yellow-brown; Mix of grassy and black tea flavors

$0.10/tea bag

[$0.09]

$9.99/box of 100 tea bags

USDA Organic seal.

Organic Green Tea leaves.

1 tea bag
Calories 0, Total Fat 0 g, Total Carbohydrate 0 g, Protein 0 g.

APPROVED

Top Pick

for brewable green tea

Trader Joe's Organic Green Tea

Dist. by Trader Joe's

1 tea bag
1.8 g

Organic green tea

Foundⓘ
EGCG: 86.8 mg
Catechins: 241.5 mg
Caffeine: 34.5 mg

Metals: Pass (Lead: 0.75 mcg)

Bring water to a boil. Pour over tea bag, steeping only 2-3 minutes, no longer. If steeped too long, it may become bitter.

Color & Taste:
Yellow-green; Grassy flavor

$0.15/tea bags

[$0.09]

$2.99/box of 20 tea bags

USDA Organic seal. Quality Assurance International Certified Organic seal. Kosher. Fair Trade Certified seal.

100% Organic Green Tea Blend.

APPROVED

Twinings® Of London Green Tea

Dist. by Twinings North America, Inc.

1 tea bag
2.1 g

Green tea

Foundⓘ
EGCG: 59.3 mg
Catechins: 141.5 mg
Caffeine: 29.5 mg

Metals: Pass (Lead: <0.25 mcg)

Steep Time: 2 Minutes.

Color & Taste:
Light brown; Mild green-black tea flavor

$0.16/tea bag

[$0.13]

$46.99/6 boxes of 50 tea bags (300 tea bags total)

Non-GMO. Kosher.

Green Tea.

APPROVED

Yogi® Green Tea Pure Green Decaf

Dist. by East West Tea Company, LLC

$ Price Check

1 tea bag
2 g

Organic green tea

Decaffeinated (10 mg caffeine)

Foundⓘ
EGCG: 48.5 mg
Catechins: 110.5 mg
Caffeine: 3.9 mg ✔

Metals: Pass (Lead: <0.25 mcg)

Bring water just to boiling and steep 3 minutes.

Color & Taste:
Light brown; Mix of black and green tea

$0.27/tea bag

[$0.28]

$4.31/box of 16 tea bags

Non-GMO Project Verified seal. USDA Organic seal. Quality Assurance International Certified Organic seal. Vegan. Kosher.

1 tea bag
Organic Decaffeinated Green Tea Leaf 1,937 mg.

Green Tea from Loose Tea:

APPROVED

But fairly low EGCG

Vahdam® Teas 100% Pure Green Tea

Dist. by Vahdam Teas (P) Ltd.

1 tsp
2 g

Himalayan green tea

Foundⓘ
EGCG: 22.5 mg
Catechins: 75.8 mg
Caffeine: 73 mg

Metals: Pass (Lead: 0.75 mcg)

Peel the label & stick on the zipper bag. Cut open the vacuum bag. Transfer the leaves in the zipper bag. Brew a cup of tea.

Color & Taste:
Faint grey-brown; Faint grassy flavor

$0.29/tsp

[$0.65]

$14.63/3.53 oz [100 g] pouch in a box (approx. 50 servings)

None.

Himalayan Green Tea.

Matcha Powder:

APPROVED

Jade Leaf® Organic Japanese Matcha

Dist. by Jade Leaf Organics, LLC

Organic Japanese matcha powder
1/2 tsp [1 g]

16 mg to 24 mg caffeine

Found
EGCG: 51.2 mg
Catechins: 123.7 mg
Caffeine: 21 mg ✔

Note: Small serving size. Double values to get to 2 g:
EGCG: 102.4 mg
Catechins: 247.4 mg
Caffeine: 42 mg

Metals: Pass (Lead: 0.25 mcg)

Start with a standard serving 1/2 teaspoon (1 gram), and add more as desired.

Color & Taste:
Green; Grassy, smooth

$0.20 per 1/2 tsp

[$0.19]

$19.95/3.5 oz [100 g] pouch (approx. 100 servings)

USDA Organic seal.

100% Organic Japanese Matcha Green Tea Powder.

1/2 tsp
Calories 3, Total Fat 0 g, Saturated Fat 0 g, Trans Fat 0 g, Cholesterol 0 mg, Sodium 0 mg, Total Carbohydrate less than 1 g, Dietary fiber less than 1 g, Total Sugars [Includes 0 g Added Sugars] 0 g, Protein less than 1 g, more...

APPROVED

Top Pick

for matcha green tea

SuperFoods Matcha Green Tea Powder

Dist. by MRM®

Matcha powder
2 tsp [4 g]

65 mg caffeine

Found
EGCG: 316 mg
Catechins: 425.2 mg
Caffeine: 72 mg

Note: Large serving size. Halve values to get to 2 g:
EGCG: 158 mg
Catechins: 212.6 mg
Caffeine: 36 mg

Metals: Pass (Lead: 0.63 mcg)

Add 1 serving to water, juices, smoothies, and other recipes. Use 1 Serving Per Day.

Color & Taste:
Light brownish green; Grassy

$0.36/2 tsp

[$0.06]

$14.99/6 oz [170 g] pouch (approx. 42 servings)

Certified Vegan Vegan.org seal. Non-GMO, Contains No added milk, egg, soy, peanut, tree nut, fish, shellfish, wheat, gluten or yeast ingredients. Does Not Contain: Gluten; Preservatives; Refined Sugar; Sugar Alcohols; Animal Products; Filler or Additives; Artificial Ingredients, more...

Matcha Green Tea Powder.

2 tsp
Calories 15, Total Fat 0 g, Saturated Fat 0 g, Trans Fat 0 g, Cholesterol 0 mg, Sodium 0 mg, Total Carbohydrate 3 g, Dietary Fiber 1 g, Total Sugars [Includes 0 g Added Sugars] 0 g, Protein 1 g, more...

Green Tea from Packet:

N/A

Unable to approve due to inconsistent labeling of ingredients

Pique® Tea Crystals Jasmine

Dist. by Pique Tea, Inc.

1 pouch

0.6 g
Organic jasmine green tea

45 mg to 55 mg caffeine

Polyphenols: 273 - 333 mg. L-theanine: 14 - 17 mg.

Found
EGCG: 55.1 mg
Catechins: 202.4 mg
Caffeine: 47.2 mg ✔

Metals: Pass (Lead: <0.06 mcg)

2-3 servings/day recommended. Add To 8 oz Cold / Hot Water. Shake Or Stir.

Color & Taste:
Brownish yellow; Strong jasmine flavor

$1.21/packet

[$1.10]

$16.99/pouch of 14 packets

USDA Organic seal.

Organic jasmine tea.

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

Results of ConsumerLab.com Testing of Green Tea Supplements

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

Approval Statusⓘ

Product Name

Claimed and Found Amounts of Green Tea and Other Componentsⓘ

Heavy Metalsⓘ

Pill Sizeⓘ

Suggested Serving on Label

Cost for Suggested Serving

[Cost Per 50 mg EGCG Found]

Price

Notable Features

Full List of Ingredients Per Serving

APPROVED

Top Pick

for a low-dose EGCG supplement

H-E-B® Green Tea Extract 315 mg 

Dist. by H-E-B®

2 capsules

630 mg green tea extract

95 mg polyphenols

27 mg to 40 mg caffeine

Found
EGCG: 27.6 mg
Catechins: 86.4 mg
Caffeine: 24 mg ✔

Metals: NA

Large capsule

For Adults, Take Two (2) Capsules Twice Daily, Preferably With Meals.

$0.11/2 capsules

[$0.20]

$2.70/50 capsules

Gluten Free.

Precaution: This product contains 27 mg - 40 mg of naturally occurring caffeine per 2 capsule serving.

2 capsules
Green Tea Extract (Camellia sinensis) (leaf) (Standardized to contain 15% polyphenols, 95 mg) 630 mg.

Other Ingredients: Dicalcium Phosphate, Gelatin, Maltodextrin, more...

APPROVED

Nature's Bounty® Green Tea 315 mg 

Mfd. by Nature's Bounty, Inc.

2 capsules

630 mg green tea extract

94.5 mg polyphenols

27 mg to 40 mg caffeine

Found
EGCG: 27.4 mg
Catechins: 83.8 mg
Caffeine: 30 mg ✔

Metals: NA

Large capsule

For adults, take two (2) capsules twice daily, preferably with meals.

$0.20/2 capsules

[$0.37]

$10.01/100 capsules

Non-GMO. No Artificial Color, No Artificial Flavor, No Artificial Sweetener, No Preservatives, No Sugar, No Starch, No Milk, No Lactose, No Soy, No Gluten, No Wheat, No Yeast, No Fish, Sodium Free, more...

2 capsules
Green Tea Extract (Camellia sinensis) (leaf) (Standardized to contain 15% polyphenols, 94.5 mg) 630 mg.

Other Ingredients: Dicalcium Phosphate, Gelatin, Maltodextrin, more...

APPROVED

NOW® EGCg

Mfd. by Now Foods

1 veg capsule

400 mg green tea extract
(providing: 320 mg catechins, 200 mg EGCG, 4 mg caffeine)

50 mg decaffeinated green tea

Found
EGCG: 226.6 mg
Catechins: 383.4 mg
Caffeine: 1 mg ✔

Metals: Pass

Large veg capsule

Take 1 capsule daily with a meal.

$0.11/veg capsule

[$0.02]

$18.98/180 veg capsules

Non-GMO Project Verified seal. Kosher. Not manufactured with yeast, wheat, gluten, soy, milk, egg, shellfish or tree nut ingredients.

1 veg capsule
Green Tea Extract (Camellia sinensis) (Leaf) (Standardized Extract) [min. 80% Total Catechins and 50% EGCg (Epigallocatechin Gallate) (200 mg) up to 4 mg of naturally occurring caffeine] 400 mg, Decaffeinated Green Tea (Camellia sinensis) (Leaf) 50 mg, more...

APPROVED

Puritan's Pride® Green Tea Extract 

Mfd. by Puritan's Pride, Inc.

2 capsules

630 mg green tea extract

95 mg polyphenols

27 mg to 40 mg caffeine

Found
EGCG: 26.4 mg
Catechins: 81.8 mg
Caffeine: 24 mg ✔

Metals: NA

Large capsule

For adults, take two (2) capsules twice daily, preferably with meals.

$0.19/2 capsules

[$0.36]

$37.98/2 bottles of 200 capsules (400 capsules total)

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

2 capsules
Green Tea Extract (Camellia sinensis) (leaf) (Standardized to contain 15% polyphenols, 95 mg) 630 mg.

Other Ingredients: Dicalcium Phosphate, Gelatin, Maltodextrin, more...

APPROVED

Thorne® Green Tea Phytosome

Mfd. by Thorne Research, Inc.

1 capsule

250 mg green tea phytosome (green tea extract with phospholipid from sunflower)

Found
EGCG: 26.9 mg
Catechins: 51.6 mg
Caffeine: 0.2 mg

Metals: NA

Large capsule

Take 1 capsule two to three times daily or as recommended by your health-care practitioner.

$0.45/capsule

[$0.84]

$27.00/60 capsules

Gluten Free.

1 capsule
Green Tea Phytosome (Camellia sinensis extract (leaf) / Phospholipid complex from Sunflower) 250 mg.

Other Ingredients: High and low viscosity hydroxypropyl methylcellulose, more...

APPROVED

Top Pick

for a high-dose EGCG supplement

Vitacost® Green Tea Extract

Dist. by Vitacost.com, Inc.

1 capsule

500 mg green tea extract

490 mg polyphenols

400 mg catechins

250 mg EGCG

Found
EGCG: 245.1 mg ✔
Catechins: 418.7 mg ✔
Caffeine: 6 mg

Metals: NA

Large capsule

Take 1 Capsule Daily With Food Or As Directed By A Healthcare Professional.

$0.06/capsule

[$0.01]

$5.75/100 capsules

Free of: Milk, Eggs, Peanuts, Tree Nuts, Crustacean Shellfish, Fish, Soy, Gluten, Titanium Dioxide.

1 capsule
Green Tea Extract (leaf) [standardized to 98% polyphenols (490 mg), 80% catechins (400 mg), 50% epigallocatechin-3P-gallate (EGCG) (250 mg)] 500 mg.

Other Ingredients: Gelatin, more...

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:
To compare green tea products, it is helpful to look for ones that state the amount of "EGCG"-- although not all labels provide this information. More broadly, you may see the term "catechins" which includes EGCG and related compounds (catechin, epigallocatechin, epicatechin, gallocatechin gallate, epicatechin gallate and catechin gallate). These compounds are anti-oxidants and may help explain the link between green tea consumption and any potential health benefits. Catechins are themselves part of a larger class of compounds called "polyphenols" another term that you might see on labels but is more vague. In a ConsumerLab.com review of products in 2009, one product used the term "catechins/polyphenols," making it difficult to know the expected amount of catechins. In that case, it turned out that only about half of the listed amount was specifically catechins.

Should you get green tea from matcha, brewed tea, supplements, or bottled beverages?
As seen in this Review, levels of EGCG (as well as total catechins) can vary greatly among products. In general, supplements can efficiently provide the largest amounts (hundreds of milligrams) of these compounds, and matcha powders and some green teas can provide about 40 mg to 150 mg of EGCG per serving. A one cup serving of certain bottled green tea products can provide just as much in the way of green tea compounds as most brewed green teas in the U.S., but others may provide little. In fact, tests by ConsumerLab in 2012 found that Diet Snapple Green Tea, provided only 3.5 mg of EGCG per 8 fl oz. Bottled green teas also tend to contain sweeteners and other ingredients you may not want.

Looking specifically at brewed teas, a study of commercially available green teas in the U.S. found that brewing 1.5 grams (about 1 tea bag) of green tea for 5 minutes in 250 mL (about 1 cup) in hot (recently boiled) water, yielded an enormous range of catechins (about 15 to 85 mg for most products), EGCG (10 to 40 mg for most), and caffeine (5 to 20 mg for most) (Friedman, 2005 J Food Sci — This article is free online and includes results for 24 products). The researchers also experimented with brewing times from 3 minutes to 20 minutes and found no significant difference in levels of tea compounds, i.e., it is not necessary to steep tea for more than 3 minutes — it may only make the tea more bitter.. A problem with this study, however, is that it used a nylon filter prior to analysis which, we found, appears to hold back EGCG and other catechins (perhaps due to ionic binding to the nylon), suggesting that the reported levels are lower than actual levels.

A study in Great Britain found generally higher amounts of catechins in green tea. In that study, three cups of green tea (2 grams of tea brewed for 5 minutes in 200 mL of water) provided, on average, about 400 mg of catechins (Khokhar, J Agric Food Chem 2002), i.e., 133 mg per serving. In the same British study, black tea provided, on average, 31 mg per serving — about one-quarter the amount of catechins as in the green tea.

White tea (which is made from the same type of leaf as green tea but picked at a less mature stage) tends to provide comparable amounts of catechins to green tea when brewed — although potentially large variations can occur from product to product and studies have differed on whether white or green teas have the highest levels. Interestingly, one study showed green tea to have significantly higher overall antioxidant activity than white tea, presumably due to the presence of antioxidant compounds other than catechins, such as flavanol glycosides (Uchenna, J Food Sci 2010). White tea generally provides less caffeine than green tea, as well as lower amounts of lead.

Some matcha products have claimed to provide "137" times the EGCG that you get from brewed green tea. This is not correct. The "137" figure seems to originate from a small study comparing EGCG in a single brand of matcha to that in a single brand of green tea (Weiss, J Chromatogr A 2003). That study found that each gram of matcha contained 57.4 mg of EGCG, while each gram of water-brewed green tea leaf yielded only 0.42 mg of EGCG. This finding for brewed green tea seems erroneous — it is about 100 times lower than what ConsumerLab.com and many other researchers have found testing a wide range of brewed green teas. ConsumerLab.com has found that each gram of green tea leaf will provide approximately 20 to 40 mg of EGCG when brewed, although this varies by brand. Consequently, a cup of brewed green tea will provide about 30 to 60 mg of EGCG, while a cup of tea from powdered matcha will provide about 70 to 110 mg of EGCG (per level teaspoon). This higher yield of EGCG from matcha is consistent with research showing that turning green tea leaves into a powder allows them to release higher amounts of EGCG and other catechins (Fujioka, Molecules 2016). It is also interesting to note that matcha made from leaves harvested in July to make "daily" matcha provides about 12% more polyphenols (which includes catechins) than those harvested earlier, such as in April, which are used to make "traditional" matcha -- which has a smoother flavor due to the lower concentration of polyphenols (Jakubczyk, Foods 2020).

Radiation Contamination: Is Green Tea from Japan Safe?
Concerns have been raised about the possibility of radiation contamination of green tea from Japan following the 2011 Fukushima Daiichi nuclear power plant accident. Radiation contamination was initially found in some green tea grown in regions close to the accident site (Ministry of Economy and Industry of Japan 2011). A study of imported Japanese green teas purchased in Canada found that just one of four green teas purchased between 2011 and 2012 exceeded a stringent radioactivity limit set by Japan but not the limit used in Canada, and none of 11 green tea samples purchased in 2013 exceeded either limit. The researchers concluded that there is "no health concern arising from the consumption of green tea beverages" (Cook, J Environ Radioact 2016). The European Union concluded in 2014 that due to lack of radiation contamination found in Japanese green tea in the previous growing season, green tea imported from districts other than Fukushima no longer required sampling and analysis (European Union 2014). In 2015 the U.S. FDA reported that its monitoring found "no evidence that radionuclides from the Fukushima incident are present in the U.S. food supply at levels that would pose a public health concern" (FDA 2015).

What to Consider When Using:
Dosage
It is difficult to say what amount green tea or its constituent compounds may be effective for cardiovascular disease, preventing cancer, diabetes, or weight loss, but the following studies provide some guidance (see What It Does for more information):

Cardiovascular Disease:
Most studies have found an association between consuming 3 to 5 cups of green tea daily and reduced risk of heart disease and stroke. Some evidence suggests that increasing intake by 1 cup/day is associated with a 10% decreased risk of developing coronary artery disease (Wang, Am J Clin Nutr 2011).

Cholesterol-lowering benefits of green tea have also been shown, but further benefit is not seen with doses over 625 mg of green tea catechins (Zheng, Am J Clin Nutr 2011).

Cancer Prevention:
Among men with precancerous prostate lesions, the following appeared to significantly reduce the risk of developing prostate cancer: 600 mg of a highly concentrated green tea extract per day (as three 200 mg capsules) providing a total of 454 mg of total catechins, of which 311 mg was EGCG (Bettuzzi, Cancer Res 2006). A study in a similar group of men using a different extract (Polyphenon E [Mitsui Norin, Japan] — a proprietary mixture of green tea catechins providing 400 mg of EGCG per day), showed lower rates of cancer among those taking the extract but the results were not statistically significant (Kumar, Canc Prev Res 2015).

Some studies suggest that drinking 2 to 3 cups or more of green tea daily might provide protection against some forms of cancer.

Fibroids:
A study found that giving 800 mg of green tea extract (45% EGCG) daily after meals significantly reduced the size of uterine fibroids in women, as well as symptoms and anemia (Roshdy, Int J Wom Health 2013).

Diabetes:
Some studies suggest that drinking 3 or more cups of black or green tea daily is associated with a reduced risk of developing type 2 diabetes (Huxley, Arch Intern Med 2009).

Weight Loss:
Green tea extracts which include caffeine may be effective, at least short-term, for weight loss. Decaffeinated products have generally not been effective, although one study in obese men given 530 mg of decaffeinated green tea extract in capsules twice daily (providing 432 mg EGCG/day) showed a benefit. One capsule was taken an hour before breakfast and the other was taken an hour before dinner (Brown, Br J Nutr 2011).

How to use
Brewing:
To brew green tea, you only need to steep tea leaves (loose or in a tea ball or tea bag) in recently boiled water for 3 to 5 minutes to get a significant amount of EGCG without creating a bitter-tasting tea.

You can use a microwave oven to brew green tea (and it does not destroy catechins), but this is not very worthwhile. The reason, as demonstrated in a research study (Vuong, J Food Compost Anal 2012, is that microwaving a green tea bag in a cup of room-temperature water for up to 120 seconds releases only 68% of the catechins you'd get from simply brewing in recently boiled water for 3 minutes. A better release of catechins requires first steeping the bag in recently boiled water for 30 seconds and then microwaving for 60 seconds. If this is done, you can release about 29% more catechins and 21% more caffeine than from steeping alone for 3 minutes, but, like steeping for too long, the tea may become bitter. Microwaving only makes sense if you want to extract the maximum amount of catechins in the shortest period of time and you don't mind steeping the tea in boiled water first and drinking bitter tea. (Be aware that tea bags may break open if microwaved for more than 2 minutes.)

Let tea cool to a comfortable temperature before drinking, as there is an increased risk of both esophageal and gastric cancer associated with drinking hot tea. Although pesticides have been reported at trace levels in green tea, they have not been found in amounts that would elicit adverse health effects (see Quality Concerns). However, if this is of concern, pesticide residues in green tea can be reduced by about 10% with minimal loss of EGCG (no more than 5% loss) by first swirling the tea leaves in boiled water for 5 seconds, steeping for 5 to 20 seconds more, and then discarding the water before preparing tea as usual (Gao, J Agric Food Chem 2018).

A study by researchers at Cornell University in Ithaca, New York found that green tea brewed with the local tap water contained only about half the EGCG present in tea brewed with deionized or bottled water (Poland Spring). Tasters found the tap water-brewed tea less bitter (which the researchers attributed to less EGCG), although cloudier, than the others. The tap water had much higher concentrations of calcium and magnesium that the other waters. The researchers concluded "that those seeking greater health benefits should use a more purified water source to brew green tea." (Franks, Nutrients 2019). However, a special microfilter that was used in the study before chemical analysis could potentially have removed EGCG complexed with minerals in the tap water, making it appear that there was less EGCG present. On the other hand, separate research has shown that minerals in tap water may chemically change EGCG, leading to its degradation (Wang, Food Chemistry 2000). More research is needed, but, for now, it seems that your safest bet to maximizing EGCG is to brew with water that is low in minerals ("soft" water) -- but be aware that this can affect flavor.

Be aware that tea bags made from plastic (such as nylon) may release microplastics into water when brewing. A study of four different commercial loose-leaf teas packaged in individual plastic teabags purchased from grocery stores and coffee shops in Canada found that steeping a single plastic teabag at brewing temperature (203 °F) for five minutes released approximately 11.6 billion microplastic particles (100 nm to 5 mm in size) and 3.1 billion nanoplastic particles (<100 nm in size) into a single cup of water. The total amount of plastic was estimated to be about 16 mcg per cup of tea, which is "several orders of magnitude higher than levels previously reported in foods," including the highest level reported in table salt (0.005 mcg/g of salt). The tea bags were made from "food grade" nylon and polyethylene terephthalate (PET), which are used in a small percentage of tea bags (Hernandez, Environ Sci Technol 2019). The health effects of consuming microplastics are not currently known, although evidence from animal studies suggests potential adverse effects. For more information about microplastics, see the CL Answers about microplastics relating to salt and drinking water and water filters. Some tea brands, such as Numi Organic Tea, state on their website that their bags are made from compostable or only plant-based material.

Some evidence suggests that consuming green tea with dinner may have more of blood-sugar lowering effect than when consumed with breakfast (see What It Does for details).

Should you add milk?
Proteins in milk and soy can bind to and decrease the bioavailability of green tea catechins, including EGCG, so you may not want to add milk to green tea. A small study among women who drank a brewed decaffeinated tea containing a high-flavanol green tea extract (providing 445 mg of total catechins and 260 mg of EGCG — equivalent to 4 to 5 regular cups of green tea) found that replacing 20% of the water in the beverage with skim milk (1% fat, providing 2.7 grams of protein) decreased blood levels of catechins and EGCG by 87% and 68%, respectively, compared to the same tea beverage without milk. Similar reductions occurred when adding soy protein or casein (a milk protein) to the tea (Egert, Eur J Nutr 2013). This reduced bioavailability may diminish the some of the benefits of drinking tea. For example, consuming milk protein with a green tea extract supplement reduced the diet-induced thermogenic effects of the supplement (Hursel, Nutrients 2011). On the other hand, if you are prone to kidney stones and less interested in catechins, adding milk to tea will reduce your absorption of stone-forming oxalates from tea (see Concerns and Cautions).

Don't take with iron
A study in mice indicated that iron can bind to the EGCG in green tea, causing EGCG it to lose its anti-oxidant activity (Yeoh, Am J Path 2016, related news release). To avoid this problem, the researchers suggested that people should not consume green tea around the time of consuming iron-rich foods, such as red meat and dark leafy greens like kale and spinach, or with iron-containing supplements.

Conversely, just one cup of tea can significantly reduce iron absorption, so it's best to separate your consumption of tea and iron (from a supplement or food) by at least one hour. One study showed that drinking a large cup of green tea (10 oz., containing 492 mg total polyphenols) with a small meal (wheat bread with 6 mg of iron, honey and butter) reduced iron absorption by about 80% compared to drinking mineral water with the meal (Lazrak, J Nutr 2021).

Storage and shelf life:
Most brewable green tea has a "best by" date on the package. Provided the tea has been stored in appropriate conditions (i.e., in the dark, at room temperature and low moisture), it would still likely be safe to use past the "best by" date, although the flavor might not be optimal. Once a package is opened, for optimal freshness and quality, it is generally recommended that brewable green tea be used within 6 to 12 months if properly stored, for even if properly stored, a study found that EGCG in eight commercial tea leaves degraded by an average of 28% over 6 months (Friedman, J Food Sci 2009).

From supplements:
Although uncommon, there is a risk of liver injury when taking large doses of green tea extract. This risk may be somewhat reduced by taking green tea extract with food, rather than on an empty stomach.

Concerns and Cautions:

Green tea contains a significant amount of caffeine. Consequently, it can cause caffeine-related side effects and interfere with drugs that are MAO inhibitors. Even products listed as "decaffeinated" may contain up to 2% caffeine, and "caffeine free" products can contain small amounts. To help those sensitive to caffeine, we measured caffeine in the products and the results are shown in the results tables above.

Green tea and, to a slightly lesser extent, black tea, contain small amounts of fluoride. Excess fluoride can cause teeth and bones to become brittle (a condition called "fluorosis"). This is unlikely to occur with consumption of just a few cups of tea daily, but has occurred in people habitually consuming very large amounts of tea, providing approximately 20 mg or more of fluoride daily, which is above the established upper tolerable intake level (UL) for fluoride, which is 10 mg per day (IOM, 1997). A case was reported of a woman who consumed a pitcher of tea daily made with 100 to 150 tea bags. Because of brittleness, all her teeth were extracted and she experienced pain in her lower back, arms, legs and hips. Symptoms improved after discontinuing tea consumption (Kakumanu, NEJM 2013). Similar cases have been reported, including that of a women who consumed one or more pitchers of tea daily (each pitcher made with 7 double tea bags) and two cases of women consuming one to two gallons daily of instant tea (Izuora, JCEM 2011). An analysis of 47 brewable teas sold in 13 countries including the U.S, Canada, China and India found that, when brewed, green teas contained about 1.2 mg of fluoride per 6 oz. serving, while oolong and black teas contained about 1 mg and herbal teas contained just 0.1 mg (Das, Environ Pollut 2017). Average daily fluoride intake by adults in areas where water is fluoridated has been shown to range from 1.4 to 3.4 mg. Consequently, it would seem safe for a healthy adult to consume up to 5 cups of green tea or 6 cups of black tea daily without risk of fluorosis. (Note: Although green tea extract supplements are concentrated forms of green tea, there are no published reports of fluorosis from green tea supplements, likely because the common extraction process (using alcohol) would not concentrate fluoride. A water-based extraction method could, however, concentrate fluoride.)

Cancer patients taking proteasome inhibitors such as bortezomib (BZM), which is used to treat multiple myeloma, should be aware that EGCG and other polyphenols in green tea may block the action of these drugs and negate their therapeutic efficacy. Green tea should not be used when taking boronic acid-based proteasome inhibitors such as BZM, MG-262, and PS-IX (Golden, Blood 2009).

Green tea has been shown to reduce the absorption of the beta-blocker nadolol (Corgard). The effect on nadolol was demonstrated in a study of young Japanese adults who consumed 700 mL (equal to 3 cups) of a green tea drink daily (providing a total of 322 mg of EGCG). After two weeks of consuming the green tea drink, they were given a dose of nadolol (30 mg) along with the drink and, 30 minutes later, a second large cup of the drink. This resulted in blood plasma levels of nadolol 85% lower than when the same two-week experiment was conducted with just water instead of green tea (Misaka, Clin Pharm & Therapeut 2014), and the effect of nadolol on systolic blood pressure was also significantly reduced. This may be due to an inhibitory effect of green tea catechins, such as EGCG, on the OATP1A2 drug transporter in the small intestine, which is also known to be inhibited by certain fruit juices, such as grapefruit juice. This is the explanation also put forward by researchers in Korea who found that giving rosuvastatin along with 300 mg of EGCG resulted in blood levels of the drug which were 19% lower than when the drug was given alone. They speculated that a lower amount of EGCG, as found in a cup of green tea, would also reduce absorption. Interestingly, however, giving EGCG for 10 days and then giving rosuvastatin/EGCG resulted in no significant difference in the level of the drug in the body, possibly because EGCG also inhibits the elimination of the drug by inhibiting uptake of the drug into liver cells (Kim, Drug Des Devel Ther 2017).

Green tea can affect the absorption of certain statin medications, depending on the dose of green tea, the type of statin medication, and individual differences. For example, researchers in Korea found that giving rosuvastatin (Crestor) along with 300 mg of EGCG resulted in blood levels of the drug which were 19% lower than when the drug was given alone. They speculated that a lower amount of EGCG, as found in a cup of green tea, would also reduce absorption. Interestingly, however, giving EGCG for 10 days and then giving rosuvastatin/EGCG resulted in no significant difference in the level of the drug in the body, possibly because EGCG also inhibits the elimination of the drug by inhibiting uptake of the drug into liver cells (Kim, Drug Des Devel Ther 2017).

Green tea can modestly increase blood levels of the statin drug simvastatin (Zocor), possibly by inhibiting a liver enzyme (CYP3A4) which helps to break down this drug. Potentially, green tea could also increase blood levels of other statin drugs metabolized by CYP3A4 including atorvastatin (Lipitor) and lovastatin (Mevacor, Altocor). However, this effect appears to be mostly likely when consuming higher doses of green tea (> 600 mg total catechins and 300 mg EGCG per day), and in a certain subset of individuals who appear to be more susceptible to this interaction (Werba, J Food Drug Anal 2018). For example, a small study found that in people taking a 20 mg dose of simvastatin, drinking three cups of tea per day (335 mg total catechins including 173 mg EGCG daily) did not significantly increase blood levels of the drug, except that in about one-fourth of participants, blood levels increased two-fold (Werba, Curr Pharm Des 2015). This research was triggered by an earlier case in which a man taking 20 mg of simvastatin experienced statin-related muscle pain when consuming 3 cups of green tea per day. This improved when he stopped consuming the tea; laboratory tests showed his blood levels of the drug increased two-fold when he drank a single cup of green tea (Werba, Ann Intern Med 2008). Neither green tea extract (containing 150 mg of EGCG) nor brewed green tea (about 2 cups of tea containing 78 mg EGCG) taken along with a single 20 mg dose of fluvastatin (Lescol) were found to affect blood levels of that drug (Misaka, Eur J Clin Pharmacol 2018).

Overall, it appears that modest daily intake of green tea is not problematic for most people taking statins, but be aware that certain individuals may be more sensitive.

In animal studies, high doses of green tea extract and green tea catechins have been found to impair thyroid function by decreasing levels of thyroid hormones T3 and T4, increasing levels of TSH (thyroid stimulating hormone) (Bajaj, J Clin Diagn Res 2016). Like coffee, green tea naturally contains caffeine and coffee has been shown to reduce the absorption of thyroid medication in people, although it's not known if caffeine or another component of coffee is responsible for this effect. To be safe, it may be best to consume green tea at least one hour apart from thyroid medication such as levothyroxine (Synthroid).

Green tea may increase blood levels of the immunosuppressant tacrolimus (FK-506, Protopic, Prograf, Hecoria), which is also metabolized, in part, by the CYP3A4 liver enzyme (Werba, J Food Drug Anal 2018).

Women who are attempting to conceive or are in their first trimester of pregnancy should avoid large amounts of green tea. Preliminary evidence suggests that increasing maternal tea consumption is associated with increased risk of spina bifida in infants (Correa, Ann Epidemiol 2000). Catechins in tea may inhibit the conversion of folic acid into its active folate form, which is needed for normal spinal cord development. Women who are nursing should also avoid large amounts of green tea in order to limit caffeine exposure to infants.

Drinking tea, including green tea, may inhibit the absorption of iron from food. To avoid this, delay tea for at least one hour after an iron-containing meal. (For more information, see "Don't take with iron?" above and the ConsumerTips™ section of the Iron Review).

People who are prone to kidney stones are sometimes advised to avoid tea because it contains oxalate (a substance which can bind with calcium to form calcium oxalate kidney stones — the most common type of kidney stone) (Massey, J Am Diet Assoc 1993). However, this does not appear to be a concern with green tea because green tea contains significantly lower amounts of oxalate than black tea — an average of 0.68 mg/g of green tea versus 1.5 to 6.9 mg/g of black tea (Charrier, Asia Pacific J Clin Nutr 2002). [Note: Adding milk to black tea may reduce the amount of oxalate that is absorbed. In fact, some experts have concluded that, overall, consuming either green tea or black tea with milk may be helpful for people with a history of kidney stones (Charrier, Asia Pacific J Clin Nutr 2002). In addition, keeping steeping time to a minimum (3 to 5 minutes) and avoiding vigorous stirring may also reduce the amount of oxalate coming from brewed black tea (McKay, J Am Diet Assoc 1995; Mahdavi, Urolithiasis 2013)]. Furthermore, there is some evidence that green tea may actually inhibit the formation of oxalate crystals: In animal studies, green tea, and in particular, EGCG from green tea, has been shown to reduce kidney stone formation (Chen, CrystEngComm 2010; Itoh, J Urol 2005; Jeong, J Endourol 2006). Interestingly, observational studies have reported a decreased risk of kidney stone formation of 8% and 14%, respectively, in women and men without a history of kidney stones who drink 2 to 3 cups of tea (the type of tea, i.e., black or green, and use of milk in tea not reported) per day (Curhan, Ann Intern Med 1998; Curhan, Am J Epidemiol 1996).

Liver toxicity has been associated with green tea extract supplements. There are reports of several cases of toxicity beginning from five days to four months after beginning use. Liver function returned to normal in most cases after discontinuation. However, one patient required a liver transplant; the specific extract taken in this case (Exolise from Arkopharma) is reported to have been removed from the market. It is possible that certain extraction processes used in the production of green tea extracts and supplements, such as ethanolic extraction, may contribute toxic compounds to these products. It is also possible that the green tea catechins themselves are a cause of toxicity as there appears to be an association of liver injury with higher daily intakes of green tea extract (LiverTox, NIH, 2013). A case of acute liver failure reported in 2013 involved a 16-year-old male using Applied Nutrition Green Tea Fat Burner. He took 2 pills daily providing a high dose of EGCG (400 mg), although he was also using a protein powder, a high-dose multivitamin, and a cactus supplement (World J Gastroent 2013).

One case of acute hepatitis associated with drinking 3 cups of a Chinese brewable green tea (sold as tea bags) daily for 3 months has been reported (Lugg, BMJ Case Rep 2015). A small number of cases of toxicity have been reported with drinking green tea "infusions."

Several U.S. government agencies sponsored a study of the safety of green tea extract given to over 1,000 postmenopausal women at risk for breast cancer. Twice a day for a year, women in the study took 2 capsules with both morning and evening meals, providing a total of 1,315 mg of catechins, of which 843 mg was EGCG (equivalent to about 4 cups of green tea), or a placebo. There was no statistically significant difference in the overall incidence of adverse events between the two groups, but women in the extract group were more likely to experience nausea and skin rashes/allergies and less likely to report diarrhea. In addition, 6.7% of the extract group, but only 0.7% of placebo group, experienced elevations in liver enzymes — a sign of liver injury — and these elevations tended to be greater in the extract group. Enzyme levels returned to normal with discontinuation of the extract in all but one person. The researchers noted that "Though green tea has typically been associated with antioxidant effects, recent evidence has demonstrated a strong pro-oxidant effect of green tea catechins (especially EGCG) that can cause hepatotoxicity when administered in high doses." (Dostal, Food Chem Tox 2015).

The American College of Gastroenterology's clinical guideline for diagnosing and treating drug-induced liver injury, published in 2014, lists green tea extract as one of the most common dietary supplements linked to liver injury and stresses the importance of patients experiencing symptoms of liver dysfunction to inform their doctors of any supplements they may be taking (see the LiverTox Database to search for medications and supplements that may cause liver injury). One of the authors of the guidelines noted that levels of catechins can be over 700 mg in some green tea extract pills and, "This can be particularly dangerous when the pills are taken multiple times a day."

In light of potential liver toxicity, the United States Pharmacopeia (USP) added a cautionary labeling requirement in March 2019 for products that claim compliance with USP quality standards for green tea extract, that reads as follows: "Do not take on an empty stomach. Take with food. Do not use if you have a liver problem and discontinue use and consult a healthcare practitioner if you develop symptoms of liver trouble, such as abdominal pain, dark urine, or jaundice (yellowing of the skin or eyes)." The USP panel found no evidence that reports of liver damage associated with green tea were due to solvent residues, pesticides or other potential impurities in green tea, and theorized that, based on preliminary animal studies, genetic factors may play a role in making some people more susceptible to liver injury from green tea (Oketch-Rabah, Toxicol Rep 2020).

The recommendation to take green tea extract with food was given some support from tests on dogs that found that high doses of green tea extract induced lethal toxicity when given without food, but showed no significant toxicity when given with food (Wu, Int J Toxicology 2011).

In 2018 the European Food Safety Authority concluded that green tea catechins doses at or above 800 mg per day may be associated with initial signs of liver injury, while catechins from green tea infusions (brewed tea) and similar drinks are generally safe.

In summary, it may be the rapid ingestion, particularly on an empty stomach, of high amounts of catechins that explains the toxicity reported with green tea supplements. Green tea drinks (such as brewed tea), in contrast, are often spread throughout the day, provide lower amounts of catechins per serving, and are often consumed with food — slowing absorption.

Green tea leaves contain a significant amount of vitamin K (about 20 mcg in 2 grams of tea leaf — roughly the amount used to make 1 cup of tea). Boiling the leaf does not decrease the amount in the leaf by much. However, the liquid portion of brewed green tea contains hardly any vitamin K (about 0.1 mcg per cup) (Booth, JADA 1995). Consequently, matcha green tea (in which the leaf powder is consumed and would contain approximately 20 mcg of vitamin K per cup) can potentially interfere with the effectiveness of the blood-thinning drug warfarin (Coumadin). Only very large quantities of brewed green tea would provide a significant amount of vitamin K. There is one case report of a man taking warfarin (7.5 mg once daily) who had a significantly decreased INR (from 3.79 to 1.37) attributed to the ingestion of one-half to one gallon of green tea daily; his INR increased to 2.55 after he stopped drinking the green tea. On the other hand, there is also evidence that green tea catechins may have anti-clotting and anti-platelet effects, which could potentially enhance the effects of medications such as warfarin, dabigatran (Pradaxa), and clopidogrel (Plavix) (Ge, Evid Based Complement Alternat Med 2014; Tian, Sci Rep 2016). However, a review of the potential interactions between warfarin and green tea concluded that given "the rarity of reports and the massive quantity of green tea that appears to be necessary to cause an effect on anticoagulation, patients who drink moderate amounts of green tea are not at an increased risk for thrombosis and need not be counselled to avoid it." (Nutescu, Expert Opin Drug Safety 2006).

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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 Green Tea Supplements and Drinks

Green Tea for Memory?

9/29/2020

Can a green tea extract supplement improve memory or cognitive function in healthy, older men and women? Find out what a recent study showed in the What It Does section of our Green Tea Review. Also see our Top Picks for green tea supplements and drinks.

Is Expired Green Tea Safe?

8/27/2020

We were asked if it is safe to use green tea past its "best by" date and if its flavor or health benefits would be diminished. See our answer in the How to Use section of our Green Tea Review. Also see our Top Picks for green tea — including tea bags, loose tea, matcha, and green tea supplements.

Getting the Most from Green Tea

6/30/2020

Our Green Tea Review shows that matcha green tea provides higher amounts of healthful catechins than regular green tea. This week, we added information about why this is as well as the results of a new study showing which type of matcha provides the highest levels of polyphenols (i.e., catechins). For details see the What to Consider When Buying section of the review. Also see our Top Picks among green tea products.

Staying Safe With Green Tea

3/10/2020

If you use a green tea extract (alone or as part of a supplement formula), it is important to take it with food according to several reports, as explained in the Concerns and Cautions section of the Green Tea Review. Also see our Top Picks for green tea in bags, loose, as matcha powder, and in other forms.

Tea & Heart Disease

1/14/2020

Another study shows that people who drink tea are less likely to suffer from cardiovascular disease. Find out how much and what type of tea was associated with benefits in the Cardiovascular disease section of the Green Tea Review. Also see our Top Picks for green tea.

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