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Green Tea Review: Supplements, Brewable, Matcha, and Bottled
 

Initial Posting: 5/4/18 Last update: 10/16/2018
Green Tea Supplements, Drinks, and Brewable Teas Review
Sections: Jump to a section by clicking on its name.
Summary: What's the Best Way to Get Green Tea Compounds?
  • What is it? 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).
  • What does it do? 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).
  • Best products? Our tests (see What CL Found) found that amounts of EGCG in products vary widely: Supplements provided 46 mg to 500 mg per daily serving. Brewed teas (e.g., bags) provided 27 mg to 79 mg per cup. Matcha powders provided 73 mg to 119 mg per teaspoon (2 grams). Bottled green tea provided 20 mg to 59 mg per cup. (Click on each to see our Top Picks).
  • Problems with products? Four products failed our tests. One contained only 55% of its listed EGCG and three others contained significantly less caffeine than claimed on their labels. Although green tea leaves can accumulate toxic lead, none of the products were found to provide significant amounts of lead.
  • Cautions: Green tea can interfere with a range of drugs. Liver toxicity is a concern with high doses of EGCG from green tea supplements. 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).
Finding the Best Green Tea and Avoiding Dangers with CL Founder, Dr. Tod Cooperman


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 that 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 study of more one hundred thousand men in China followed 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.)

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).

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). In fact, a recent study 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).

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).

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).

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, studies have not been consistent regarding an effect on overall breast cancer risk.

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.

See the Cancer Prevention article in the Encyclopedia on this website for more information about green tea and other approaches to preventing cancer. Other ingredients with potential benefit 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).

Diabetes:
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:
Higher consumption of green tea has been associated with lower prevalence of cognitive impairment in older adults (Kuriyama, Am J Clin Nutr 2006). A study of green tea with added l-theanine, suggested that consumption improves memory and attention in subjects with mild cognitive impairments (Park, J Med Food 2011).

In addition, even "regular" tea consumption, especially of green tea, has been associated with reduced risk of cognitive decline among people with normal cognitive function. 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).

However, a study in Japan suggests 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 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 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).

Some excitement was generated by a Swiss study in 2014 reported by some news sources as showing that green tea 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 is 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).


For more about studies of green tea and its other potential uses, see the Green Tea article in the Encyclopedia on this website.

Quality Concerns and What CL Tested for:
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 and beverages 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 commonly available green tea supplements, bottled drinks, brewable tea products (tea bags, loose tea, and K-Cup), and matcha powders and examined them 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:

Green Tea Supplements:
Among the eight green tea supplements selected by CL for testing, seven passed quality testing as did four additional supplements evaluated through ConsumerLab.com's voluntary Quality Certification Program.

Problem
The one supplement that failed testing was Green Foods™ Organic Matcha Green Tea Drink. Although its label may suggest that this is "matcha," a closer look shows that it is a matcha powder "drink." The word "drink" is a tip-off that, like fruit "drinks" that are not 100% fruit, this product is not 100% matcha. In fact, a careful reading of the label suggests it is only 20% matcha: The suggested 5 gram serving (2 teaspoons) of the powder includes only 1 gram (1,000 mg) of matcha, while "Organic Brown Rice Solids" is the only other listed ingredient. Therefore, rice seems to account for 80% of this matcha product.

A serving is listed as providing 83 mg of EGCG, but ConsumerLab's tests found only 46 mg — just 55.4% of the listed amount. An equal-sized serving of a real (100%) matcha powder would normally provide about 10X the EGCG found in this product. (see matcha results below).

Top Pick
Among the supplements that were Approved, amounts of EGCG per suggested daily serving ranged from about 65 mg to 326 mg -- and as much as 500 mg at the maximum dose of Zhou Green Tea Extract (2 capsules). In comparison, a cup of brewed green tea in the U.S. contains about 20 mg to 80 mg of EGCG, depending on the tea, so most of these supplements provide amounts of EGCG comparable to at least one or two, if not many more, cups of green tea. Amounts of EGCG typically used in clinical trials of green tea extracts tend to range from about 200 mg to 400 mg. Although rare, it is worth noting that cases of liver toxicity have been reported with green tea extracts, particularly those providing hundred 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). It would seem prudent not to exceed serving sizes listed on these products and not take the maximum serving size (2 capsules) of the Zhou product.

Caffeine in the supplements ranged from just 1 mg to 49 mg (see second and fifth columns of the table below). As a point of reference, a cup of brewed green tea contains about 40 mg of caffeine (and somewhat more in matcha), a cup of coffee contains about 100 mg of caffeine and a can of cola contains about 40 mg.

Comparing the cost of obtaining EGCG from the supplements as shown in the last column of the Results table (based on getting 200 mg of EGCG) shows the lowest cost to be Vitacost Green Tea Extract: For just 6 cents per capsule, it provides 250 mg of EGCG, and a relatively small amount (7 mg) of caffeine, making it our Top Pick. Close behind is NOW EGCg Green Tea Extract, which provides 200 mg of EGCG (and just 2 mg of caffeine) for 7 cents per capsule.

Brewable Green Tea — Tea bags, Loose tea, K-cup:
There were no problems found with any of the eight brewable green tea products selected for review. However, they ranged considerably in EGCG strength. As shown in the graph below, the amount of EGCG in one cup of brewed tea ranged from little as 30.2 mg (Salada Decaffeinated Green Tea) to as much as 79 mg (Lipton Pure Green Tea). It is interesting to note that Salada (which also had the lowest amount of catechins), was the blandest tea tasted.

It is also interesting to note that the tea bag that produced a tea with the greenest in color, Kirkland Signature [Costco] Green Tea (a blend of sencha and matcha green tea), provided a relatively small amount of EGCG (26.9 mg) per cup, although a relatively high amount of total catechins, helping to explain its somewhat stronger flavor and astringency.

Top Picks
In addition to having the largest amount of EGCG per cup, Lipton had the largest amount of total catechins. A tea bag of Lipton cost just 11 cents — less than half the price of some other brands, and had a pleasant, mild green tea flavor. All these factors make Lipton Pure Green Tea our Top Pick among brewable green teas.

Note that Lipton contained 36.7 mg of caffeine. If you are trying to avoid caffeine, our Top Pick among brewable decaffeinated green teas is Trader Joe's Specialty Teas Decaffeinated Green Tea, which is also 11 cents per bag, provides 70.3 mg of EGCG with just 6.4 mg of caffeine, and, like Lipton, has a mild green tea flavor. Some websites suggest that decaffeinated green tea contains lower amounts of EGCG and catechins. Our findings don't support this.

By far the most expensive way to get EGCG from a brewable tea was Celestial Seasonings Green Tea K-cups. This product is actually a combination of green tea and white tea, explaining why a K-cup was found to provide only 32.4mg of EGCG despite containing about twice as much tea leaf (3.4 grams) as most tea bags (usually less than 2 grams). When we compared the cost to get a dose of 200 mg of EGCG from each product, Celestial came in at a whopping $3.60, compared to as little as 26 cents from Lipton.

None of the brewed teas contained a significant amount of lead. However, be aware tea leaves themselves can contain small amounts of lead and they are not intended to be directly consumed.

Matcha Green Tea:
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. 

From a dietary standpoint, what sets matcha apart from brewed green tea is that you are consuming the leaf as opposed to discarding it. So what are you getting by, essentially, eating the leaf? More antioxidants? More contaminants? We purchased several matcha products to find out, including four matcha powders and two products in tea bags which include matcha. We tested matcha powders using the same method we use with herbal supplements, such as the green tea supplements above, but we tested the matcha-containing tea bag products by seeping them in hot water, per their instructions, and testing the liquid tea.

As shown in the graph below, matcha powders (based on a 2 gram serving — about 1 teaspoon) provided the largest amounts of catechins of any type of green tea, other than supplements. In most cases, they also provided the most EGCG. However, the amount of EGCG ranged widely: Kiss Me Organics Organic Matcha had the least at 59.8 mg, while Organic Kenko Tea Matcha had double that amount at 118.8 mg! [Note: This version of Kenko is promoted online by its distributor as "Ceremonial Grade," although it is not stated on the label]. 

Matcha is the only type of green tea meant to be directly consumed and, fortunately, contamination with lead and other heavy metals (cadmium and arsenic) was not found to be a problem with the tested products. This is consistent with tests in earlier years by ConsumerLab.com and the fact that all the matcha powders were identified as coming from Japan.

Problem
Although not a major problem, two matcha powders could not be Approved because they did not contain the amounts of caffeine listed on their labels. Jade Leaf Organic Japanese Matcha claimed that a 1 gram serving provided 34 mg of caffeine, but it was found to contain about half that amount (18.9 mg). Kiss Me Organics Organic Matcha claimed that a 3 gram serving provided 90 mg of caffeine, but it was found to contain only 70% of that amount (63 mg).

Top Pick
Kenko provided, by far, the greatest concentration of EGCG (118.9 mg per 2 grams) among the matcha powders. It also had the highest ratio of EGCG to total catechins of any of the products (other than supplements) tested. However, it was also, by far, the most expensive matcha. A small, 1 oz (30 gram) container cost $27.97, as compared, for example, to Superfoods by MRM Raw Matcha Green Tea which cost only $14.06 for a 6 oz (170 gram) pouch and had the 2nd highest concentration of EGCG (91.8 mg per 2 grams). On an EGCG basis, Kenko is about 9 times as expensive as Superfoods.

Taking cost as well as EGCG levels into consideration, our Top Pick among matcha powders is SuperFoods. However, if cost is not much of an issue for you and you want the highest concentration of EGCG per cup of matcha, Kenko is the best choice. It also has a milder flavor than Superfoods, which has a stronger, more astringent taste likely due to its greater concentration of total catechins (248.9 mg) compared to Kenko's 188.8 mg in a 2 gram serving.

Bottle Green Tea:
None of the four bottled green tea products selected for testing listed amounts of EGCG or catechins. Testing found that, based on a serving of 8 fl oz (one cup), Harney & Sons Organic Green had the most EGCG at 59.3 mg. Honest Tea Organic Honey Green Tea has the second most, 45.6 mg — making both highly comparable to real brewed green tea, as shown in the graph below. The other two bottled teas contained substantially lower amounts of EGCG , below what one would expect from a cup of brewed tea: Pure Leaf Unsweetened Green Tea provided 22.6 mg per cup and Ito En Oi Ocha Unsweetened Green Tea provided just 19.8 mg.

Cost-wise, the bottled teas were the most expensive ways to get EGCG among the products reviewed. To get a 200 mg of EGCG would cost $6.69 from Ito En, and even the least expensive option, Pure Leaf, would cost $2.39.

Heavy metal contamination was not found to be a problem with any bottled green teas.

Problem
As with some of the matchas, Honest Tea Organic Green Tea did not contain the amount of caffeine listed on its label. Per 16.9 fl oz bottle it claimed 94 mg of caffeine (this works out to 44.5 mg per 8 fl oz cup). However, our tests found it contained only 30.5 mg of caffeine per cup. This is not out of line with what one would expect from brewed green tea, but is only 68.6% of what was claimed.

Top Pick
As none of the bottled green teas made a claim regarding their EGCG green tea content, they received no overall approval rating from ConsumerLab. Our favorite tasting bottled green tea was Pure Leaf, which is unsweetened and had a mild green tea flavor with a hint of peach from added "natural flavors." It is also inexpensive — just $2 for a 64 fl oz bottle. Unfortunately, Pure Leaf, like Ito En (which is also unsweetened), is, from an EGCG perspective, like a diluted cup of brewed green tea, so neither would be a Top Pick.

Among sweetened green teas we preferred Honest Tea Organic Honey Green Tea, which is slightly sweet with a light, green tea taste, to Harney & Son, which has a more complex (although not more appealing) flavor due to a variety of other ingredients (including Ginkgo biloba leaves and lemongrass). Honest Tea is also a bit less expensive than Harney & Son.

Although Honest Tea was a bit dishonest about its caffeine content, it provides a good amount of EGCG per cup and, for those who don't mind a few unnecessary Calories (about 30 per cup), it is our Top Pick among bottled green teas.



Test Results by Product:
Listed below are the test results for 30 products: 12 supplements, 10 brewable green teas, four matcha powders, and four bottled green tea beverages. ConsumerLab.com selected 26 of the products. Four 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 (shown in the second column of the supplements table). Products listed as "Approved" met their label claims and ConsumerLab.com's quality criteria (see Passing Score). Approval did not apply to bottled teas.

The full list of ingredients (including special dietary designations) is available for each supplement and beverage product by clicking on the word "Ingredients" in the first column.

RESULTS OF CONSUMERLAB.COM TESTING OF GREEN TEA SUPPLEMENTS
Click on beneath a product name to find a vendor that sells it.
Product Name, Listed Amount of Green Tea Per Unit, Serving Size, and Suggested Daily Serving on Label

Click on "Ingredients" for Full Listing
Claimed Amount of EGCG and Other Components Per Daily Serving

(M) = Minimum Expected1
—TEST RESULTS—

(See How Products Were Evaluated)
Cost For Daily Suggested Serving On Label

[Cost per 200 mg EGCG]

Other Notable Features4

Price Paid
OVERALL RESULTS:

APPROVED or
NOT APPROVED
Contained Expected Amounts of EGCG and Total Catechins Per Serving (as Listed in Second Column) Contained Claimed Amount of Caffeine Per Daily Serving2 Did Not Exceed Contamin-ation Limits for Lead, Cadmium and Arsenic3
GNC Herbal Plus® Green Tea Complex 500 mg (total of 500 mg from two extracts)5 per capsule; 1 capsule, once daily)

Dist. by General Nutrition Corporation
Ingredients
500 mg extract5

125 mg EGCG5

Large capsule
APPROVED
Found 131.4 mg EGCG and 211.3 mg catechins per daily serving
Found 17.2 mg caffeine per daily serving NA $0.20

[$0.32 based on amount claimed]
[$0.30 based on amount found]

No wheat, gluten free, yeast free

$19.99/100 capsules
Green Foods™ Organic Matcha Green Tea Drink (1,000 mg matcha powder per 2 tsp; 2 tsp, no daily servings specified)
NOTE: 2 tsp of powder is 5 grams, of which only 1,000 mg is matcha green tea. The majority may be rice powder.

Dist. by Green Foods Corp.
Ingredients
1,000 mg6 organic matcha green tea

83 mg6 EGCG

179 mg6 catechins

62 mg6 epigallocatechin

16 mg6 epicatechin gallate

12 mg6 epicatechin

25 mg6 theine (tea caffeine)

Powder in container
NOT
APPROVED
Found only 46 mg6 EGCG (55.4% of listed amount) and 142 mg6 catechins (79.3% of listed amount) per daily serving
Found 20.1 mg caffeine per daily serving6
$0.326

[$0.77 based on amount claimed]
[$1.39 based on amount found]

Organic brown rice solids, vitamin C (3 mg6), vitamin A (beta carotene) (215 mcg6), tannin (137 mg6), ORAC score (1,774 units6), total amino acids (16 mg6); Certified Vegan Vegan.com Seal; USDA Organic Seal

Suitable for vegans, non-GMO, organic, gluten free

$19.82/11 oz [312 g] container (approx. 62 servings)
HerbaSway® HerbaGreen (100 mg extract per 1 full dropper [1 ml]; 1 full dropped, three times or more daily7)

Dist. by Herbasway® Laboratoris, LLC
Ingredients
300 mg8 extract

150 mg8 EGCG

Caffeine free

Liquid from bottle
APPROVED
Found claimed amounts of EGCG

Found 246 mg8 catechins per daily serving

Found 1 mg8 caffeine per serving
NA $0.848

[$1.13]

Proprietary blend of Lo Han extract and Stevia extract (75 mg8), Lotus extract (75 mg8), Kudzu extract (30 mg8), deglycyrrhizinated licorice extract (6 mg8)

$16.89/2 fl oz [60 ml] bottle (approx. 60 servings)
Kroger® Green Tea (500 mg extract per capsule; 1 capsule, once daily) 

Dist. by The Kroger Co.
Ingredients
500 mg extract

175 mg EGCG

350 mg catechins

40 mg caffeine

Large capsule
APPROVED
Found claimed amounts of EGCG
and total catechins
NA $0.15

[$0.17]

Gluten free

$7.49/50 capsules
Life Extension® Mega Green Tea Extract (725 mg extract per vegetarian capsule; 1 vegetarian capsule, once daily)  

Dist. by Quality Supplements and Vitamins, Inc.
Ingredients
725 mg

326.25 mg EGCG

Approximately 25 mg caffeine

Large vegetarian capsule
APPROVED
Found claimed amounts of EGCG

Found 548.5 mg catechins per daily serving

Found 17.2 mg caffeine per daily serving
NA $0.24

[$0.14]

Non-GMO

$23.63/100 vegetarian capsule
NOW® EGCG (400 mg extract and 50 mg leaf powder per veg capsule; 1 veg capsule, once daily)  

Dist. by NOW Foods
Ingredients
400 mg extract

50 mg decaffeinated leaf powder

200 mg9 EGCG

322 mg catechins10 (M)

Up to 4 mg10 caffeine

Large veg capsule
APPROVED
Found 245.6 mg EGCG and 374.9 mg catechins per daily serving

Found 1.7 mg caffeine per daily serving
$0.07

[$0.07 based on amount claimed]
[$0.06 based on amount found]

Not manufactured with wheat, gluten and yeast

$12.98/180 veg capsules
Solgar® Green Tea Leaf Extract (400 mg extract and 100 mg leaf powder per vegetable capsule; 1 vegetable capsule, once daily) 

Mfd. by Solgar, Inc
Ingredients
400 mg extract

100 mg leaf powder

Approximately 32 mg caffeine

Large vegetable capsule
APPROVED
Found 65.7 mg EGCG and 137.2 mg catechins per daily serving

Found 47.5 mg caffeine per daily serving
$0.22

[$0.67 based on amount found]

Kosher, suitable for vegetarians, free of wheat, gluten and yeast

$13.28/60 vegetable capsules
Spring Valley™ [Walmart] Green Tea (315 mg extract per capsule; 2 capsules, three times daily) 

Dist. by Wal-Mart Stores, Inc.
Ingredients
1,890 mg extract

189 mg catechins (M)

Large capsule
APPROVED
Found 66.7 mg EGCG and 240.8 mg catechins per daily serving
Found 41.4 mg caffeine per daily serving $0.42

[$1.26]

Hoodia (75 mg)

No wheat, gluten and yeast

$4.91/70 capsules
Swanson® Superior Herbs Green Tea Extract (500 mg extract and 50 mg leaf powder per capsule; 1 capsule, once to twice daily)  

Dist. by Swanson Health Products
Ingredients
500 mg to 1,000 mg extract

50 mg to 100 mg leaf powder

52 mg to 104 mg catechins (M)

Large capsule
APPROVED
Found 73.6 mg to 147.2 mg EGCG and 179.4 mg to 358.7 mg catechins per daily serving
Found 24.8 mg to 49.6 mg caffeine per daily serving $0.12-$0.24

[$0.33 based on amount found]

$7.29/60 capsules
Vitacost Green Tea Extract (500 mg extract per capsule; 1 capsule, once daily)

Dist. by Vitacost.com®
Ingredients
500 mg extract

250 mg EGCG

400 mg catechins

Large capsule
APPROVED
Found claimed amounts of EGCG and total catechins
Found 7.2 mg caffeine per daily serving NA $0.06

[$0.05]
Lowest cost for EGCG from any product

Free of gluten

$5.75/100 capsules
Whole Foods Market™ Green Tea (250 mg extract and 200 mg leaf powder; 1 vegan capsule, once to twice daily)  

Dist. by Whole Foods Market
Ingredients
250 mg to 500 mg extract

200 to 400 organic leaf powder

125 to 250 mg EGCG9

Large vegan capsule
APPROVED
Found 148.8 to 297.5 mg EGCG and 225.8 mg to 451.5 mg catechins per daily serving
Found 5.8 mg to 11.7 mg caffeine per daily serving $0.11-$0.22

[$0.18 based on amount claimed]
[$0.15 based on amount found]

Kosher, suitable for vegans

$10.99/100 vegan capsules
Zhou Green Tea Extract (500 extract per veggie capsule; 1 veggie capsule, once to twice daily)

Mfd. by Zhou Nutrition®
Ingredients
500 mg to 1,000 mg extract

250 mg to 500 mg EGCG

400 mg to 800 mg catechins

Large veggie capsule
APPROVED
Found claimed amounts of EGCG and total catechins
Found 2.8 mg to 5.7 mg caffeine per daily serving NA $0.15-$0.30

[$0.12]

Non-GMO, zero wheat and gluten

$17.85/120 veggie capsules
Tested through CL's Quality Certification Program prior to, or after initial posting of this Product Review.

1 Minimum amount of total catechins expected is 10% of green tea extract by weight and 4% of green tea herb (non-extract) by weight.
2 Allowed 100%-120% of claimed amount of caffeine. If product claimed less than 50 mg caffeine per serving, it is allowed to have +/- 10 mg per serving of claimed amount. For products that claim to be "decaffeinated" or "caffeine free", it must contain less than 0.1% (w/w) caffeine.
3 Products were only tested for lead, cadmium and arsenic if they contain any whole herbs and/or 250 mg or more minerals daily.
4 Not tested but claimed on label.
5 Product contains 250 mg of each of two extracts: one is standardized to 14% polyphenols and the other to 75% polyphenols as well as 50% EGCG.  
6 Based on 1 serving daily.
7 Label states "Mix one full dropper in hot or cold water. For maximum benefits drink 3 times or more daily."
8 Based on 3 servings daily.
9 Claimed just from extract.
10 Total expected catechins is calculated using the listed amount of catechins from extract and minimum amount expected (4%) of leaf powder.
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, 2018. 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 BREWABLE GREEN TEA AND MATCHA
Click on beneath a product name to find a vendor that sells it.
Product Name and Suggested Serving Size on Label

Click on "Ingredients" for Full Listing
Amount of Tea Leaf or Matcha Per serving

Claimed Amount of EGCG and Other Components Per Daily Serving

Brewing Directions

Color and Taste of Tea Produced
—TEST RESULTS—

(See How Products Were Evaluated)
Cost For Daily Suggested Serving On Label

[Cost per 200 mg EGCG]

Other Notable Features2

Price Paid
OVERALL RESULTS:

APPROVED or
NOT APPROVED
Amounts of EGCG and Total Catechins Per Brewed Tea or Matcha Amount of Caffeine Per Brewed Tea or Matcha1 Did Not Exceed Contamin-ation Limits for Lead, Cadmium and Arsenic
Green Tea From Tea Bag:
Bigelow® Green Tea - Decaffeinated (1 tea bag)  

Dist. by RC Bigelow, Inc.
Ingredients
1.5 g

Decaffeinated

"Start with fresh cold water and bring to a rolling boil. Pour over teabag, steep for 4 minutes (or whatever time you like), remove bag"

Color & Taste:
Amber/green; mild green tea flavor
APPROVED Found 37 mg EGCG and 95.4 mg catechins in brewed 8 fl oz
Found 4.4 mg caffeine in brewed 8 fl oz
$0.10

[$0.52]

USDA Organic Seal; Quality Assurance International Certified Organic

Kosher, organic, gluten-free

$3.82/40 tea bags
Lipton™ Pure Green Tea (1 tea bag)  

Dist. by Unilever Foods Solution
Ingredients
2 g

"Boil fresh water and allow to cool for 30 second. Pour water over a tea bag and brew 1-1½ minutes."  

Color & Taste:
Amber/green; mild green tea flavor
APPROVED Found 79 mg EGCG and 150.7 mg catechins in brewed 8 fl oz Found 36.7 mg caffeine in brewed 8 fl oz $0.11

[$0.26]
Lowest cost for EGCG from tea bag

$10.57/100 tea bags
Numi® Organic Tea Gunpowder Green (1 tea bag)  

Dist. by Numi, Inc.
Ingredients
2 g

"Steep in freshly boiled water for 2-3 minutes."

Color & Taste:
Amber; More oxidized green tea flavor
APPROVED Found 52.6 mg EGCG and 94.4 mg catechins in brewed 8 fl oz Found 41.3 mg caffeine in brewed 8 fl oz $0.25

[$0.95]

USDA Organic Seal

Non-GMO, organic, gluten-free

$13.50/3 boxes 18 tea bags each box (54 tea bags total)
Salada® Decaffeinated Green Tea (1 tea bag)  

Dist. by Redco Foods, Inc.
Ingredients
1.5 g

Decaffeinated

"Use 1 tea bag for each cup of tea. Allow fresh cold water to come to a boil. Remove from heat and let cool for 1 minute. Pour water over tea bag and steep 2-3 minutes."

Color & Taste:
Amber; Bland — little green tea flavor  
APPROVED Found 30.2 mg EGCG and 60.8 mg catechins in brewed 8 fl oz
Found 3 mg caffeine in brewed 8 fl oz
$0.17

[$1.10]

Gluten-free

$13.25/2 boxes 40 tea bags each box (80 tea bags total)
Trader Joe's® Specialty Teas Decaffeinated Green Tea (1 tea bag)  

Dist. by Trader Joe's
Ingredients
1.9 g

Decaffeinated

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

Color & Taste:
Amber; Mild green tea flavor
APPROVED Found 70.3 mg EGCG and 141.5 mg catechins in brewed 8 fl oz
Found 6.4 mg caffeine in brewed 8 fl oz
$0.11

[$0.33]

$2.29/20 tea bags
Twinings® 100% Organic Pure Green (1 tea bag)  

Dist. by Twinings North America, Inc.
Ingredients
1.7 g

"Steep Time: 2 Minutes"

Color & Taste:
Amber/green: Mild green tea flavor
APPROVED Found 57.6 mg EGCG and 125.7 mg catechins in brewed 8 fl oz Found 31.4 mg caffeine in brewed 8 fl oz $0.27

[$0.94]

USDA Organic Seal

Organic

$32.50/6 boxes 20 tea bags each box (120 tea bags total)
Green Tea From Loose Tea:
Davidson's Organics Gunpowder Green (1-2 tsp)

Dist. by Davidson's Organic Teas, Herbs, Cocoa & Spices
Ingredients
2.3 g - 4.6 g

"2-3 mins. With water under boiling point."

Color & Taste:
Amber/green; More oxidized green tea flavor
APPROVED Found 43.7 mg to 87.4 mg EGCG and 83.4 mg to 166.8 mg catechins in brewed 8 fl oz Found 45.1 mg to 90.2 mg caffeine in brewed 8 fl oz $0.05-$0.10

[$0.23]
Lowest cost for EGCG from any brewed tea

USDA Organic Seal.

Kosher, organic

$9.99/1 lb pouch (approx. 197 servings3)
Green Tea From K-Cup:
Celestial Seasonings® Green Tea (1 K-Cup)  

Dist. by Celestial Seasonings, Innc. The Hain Celestial Group, Inc.
Ingredients
3.4 g

"For use in all Keurig® K-Cup® brewers."  

Color & Taste:
Amber; More oxidized green tea flavor
APPROVED Found 32.4 mg EGCG and 126.7 mg catechins in brewed 8 fl oz Found 42.7 mg caffeine in brewed 8 fl oz $0.58

[$3.60]

$13.99/24 K-Cups
Matcha Powder:
Jade Leaf Organic Japanese Matcha (1/2 tsp)

Dist. by Jade Leaf Organics, LLC
Ingredients
1 g

34 mg caffeine

"Start with a standard serving ½ teaspoon (1 gram), and add more as desired."  

Color & Taste:
Light green: Moderate green tea flavor
NOT
APPROVED
Found 36.5 mg EGCG and 120 mg catechins per ½ tsp   Found only 18.9 mg caffeine per ½ tsp (55.6% of listed amount) $0.33

[$1.82]

USDA Organic Seal

Suitable for vegans, organic, gluten free

$9.95/1 oz [30 g] pouch (approx. 30 servings)
Kiss Me Organics® Organic Matcha (1 tsp)  

Dist. by Kiss Me Organics LLC
Ingredients
3 g

122 mg epigallocatechin

90 mg caffeine

"Add 1 teaspoons of Matcha to your favorite smoothie recipes."

Color & Taste:
Light green: Moderate green tea flavor
NOT
APPROVED
Found 89.7 mg EGCG and 337.6 mg catechins per 1 tsp Found only 63 mg caffeine per 1 tsp (70% of listed amount) $0.68

[$1.51]

USDA Organic Seal

Suitable for vegans, non-GMO, organic

$25.00/4 oz [113 g] pouch (approx. 37 servings)
Organic Kenko Tea Matcha (1/2 tsp) [Note: Although not stated on label, this product is described online as "Ceremonial Grade"]  

Dist. by Kenko Tea
Ingredients
1.5 g

"Stir ½ tsp Matcha into a bowl, add 75 ml/2.5 fl oz of hot water and whisk until frothy."  

Color & Taste:
Bright green: Mild green tea flavor (also more "clumpy" than others when mixing with water)
APPROVED Found 89.1 mg EGCG and 141.6 mg catechins per ½ tsp   Found 48.2 mg caffeine per ½ tsp   $1.40

[$3.14]

USDA Organic Seal

Suitable for vegans, non-GMO, organic

$27.97/1 oz [30 g] container (approx. 20 servings)
Superfoods by MRM® Raw Matcha Green Tea Powder (2 tsp)  

Dist. by MRM®
Ingredients
4 g

65 mg caffeine

No directions listed

Color & Taste:
Yellowish light green: Strong (bitter) green tea flavor
APPROVED Found 183.6 mg EGCG and 497.7 mg catechins per 2 tsp $0.33

[$0.36]
Lowest cost for EGCG from matcha powder

Certified Vegan Vegan.com Seal

Suitable for vegans, does not contain gluten

$14.06/6 oz [170 g] pouch (approx. 42 servings)
Matcha From Tea Bag:
Kirkland Signature™ [Costco] Green Tea A blend of Sencha & Matcha (1 tea bag)  

Dist. by Costco Wholesale Corporation
Ingredients
1.6 g

"Place the tea bag into your cup and pour in hot water (176°F or 80°C). After just 20 to 30 seconds shake the tea bag in the hot water 3 to 4 times, remove and enjoy. Empty remaining Matcha from outer envelope to surface of tea."  

Color & Taste:
Green; Moderate green tea flavor
APPROVED Found 26.9 mg EGCG and 145 mg catechins in brewed 8 fl oz Found 24.7 mg caffeine in brewed 8 fl oz $0.13

[$0.97]

$12.99/100 tea bags
Organic Matcha DNA® (1 tea bag)  

Dist. by Accelerated Intelligence Inc.
Ingredients
1.5 g

"Place tea bag in a cup. Pour hot water (176F / 80C) into the cup and steep for 30 to 40 seconds. Shake and remove the tea bag. Empty remaining Matcha powder from inside the envelope into the cup"

Color & Taste:
Amber/green; Mild green tea flavor
APPROVED Found 42.7 mg EGCG and 92.1 mg catechins in brewed 8 fl oz Found 23.6 mg caffeine in brewed 8 fl oz $0.20

[$0.93]

USDA Organic Seal

Kosher

$19.92/100 bags
1 Allowed 100%-120% of claimed amount of caffeine. If product claimed less than 50 mg caffeine per serving, it is allowed to have +/- 10 mg per serving of claimed amount. For products that claim to be "decaffeinated" or "caffeine free", it must contain less than 0.1% (w/w) caffeine.
2 Not tested but claimed on label.
3 Based on 1 tablespoon per serving.
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, 2018. 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 BEVERAGES
Click on beneath a product name to find a vendor that sells it.
Product Name and Suggested Serving Size on Label

Click on "Ingredients" for Full Listing
Claimed Amount of Green Tea Components Per Serving

Calories Per Serving

Sweeteners

Color and Taste
—TEST RESULTS—

(See How Products Were Evaluated)
Cost Per Serving

[Cost per 200 mg EGCG]

Other Notable Features2

Price Paid
Contained Expected Amounts of EGCG and Total Catechins Per Serving (as Listed in Second Column) Contained Claimed Amount of Caffeine Per Serving Did Not Exceed Contamin-ation Limits for Lead, Cadmium and Arsenic1
Harney & Son Organic Green (8 fl oz)

Mfd. by Harney & Sons Hudson
Ingredients
Catechins and caffeine not listed

20 Calories

Organic cane sugar, organic honey

Color & Taste:
Amber-green; Slightly sweet, complex flavors from other ingredients
Found 59.3 mg EGCG per 8 fl oz

Found 105.3 mg catechins per 8 fl oz

High amounts of EGCG and catechins, comparable to brewed green tea
Found 38.2 mg caffeine per 8 fl oz $1.33

[$4.50]

USDA Organic Seal

Kosher, organic

$32.00/12 pack of 16 fl oz bottles (approx. 24 servings)
Honest Tea® Organic Honey Green Tea (1 bottle [16.9 fl oz])  

Dist. by Honest Tea, Inc.
Ingredients
94 mg caffeine per serving (44.5 mg per 8 fl oz)

70 Calories (33.1 Calories per 8 fl oz)

Fair trade organic cane sugar, organic honey

Color & Taste:
Amber-green; Light green tea taste, slightly sweet
Found 45 mg EGCG per 8 fl oz (95 mg per 16.9 fl oz serving)

Found 82.9 mg catechins per 8 fl oz (175.1 mg per 16.9 fl oz serving)

Moderate amounts of EGCG and catechins, comparable to brewed green tea
Found only 30.5 mg caffeine per 8 fl oz (64.5 mg per 16.9 fl oz serving) (68.6% of listed amount) $1.79

[$3.77]

USDA Organic Seal

Kosher, organic

$1.79/16.9 fl oz bottle
Ito En Oi Ocha Unsweetened Green Tea (8 fl oz)

Dist. by Ito En (North America) Inc.
Ingredients
Catechins and caffeine not listed

0 Calories

NL

Color & Taste:
Amber; A more oxidized green tea flavor
Found 19.8 mg EGCG per 8 fl oz

Found 63.5 mg catechins per 8 fl oz

Low amounts of EGCG and catechins
Found 30.7 mg caffeine per 8 fl oz $0.66

[$6.69]

Non GMO Project Verified Seal

Non-GMO

$15.89/12 pack of 16.9 fl oz bottles (approx. 24 servings)
Pure Leaf Unsweetened Green Tea (12 fl oz)

Dist. by Pepsi/Lipton Tea Partnership
Ingredients
Catechins and caffeine not listed

0 Calories

NL

Color & Taste:
Pale amber-green; Mild green tea flavor with a hint of peach
Found 22.5 mg EGCG per 8 fl oz (33.5 mg per 12 fl oz serving)

Found 62.9 mg catechins per 8 fl oz (94.4 mg catechins per 12 fl oz serving)

Low amounts of EGCG and catechins
Found 14.2 mg caffeine per 8 fl oz (21.3 mg per 12 fl oz serving) $0.40

[$2.39]
Lowest cost for EGCG from bottled green tea

Kosher

$2.00/64 fl oz bottle (approx. 5 servings)
1 Allowed 100%-120% of claimed amount of caffeine. If product claimed less than 50 mg caffeine per serving, it is allowed to have +/- 10 mg per serving of claimed amount. For products that claim to be "decaffeinated" or "caffeine free", it must contain less than 0.1% (w/w) caffeine.
2 Not tested but claimed on label.
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, 2018. 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 100 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, provide 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. 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, 2002), i.e., 133 mg per serving. These levels are more consistent with those which we found. 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 claim 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). 

What to Consider When Using:
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).

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. However, the study used a very high ratio of iron to EGCG, which ConsumerLab.com calculates to be equivalent to ingesting 73 mg of iron (as in 12 full steaks or 90 cups of fresh spinach) for every 100 mg of EGCG (as in about 2 cups of green tea). Therefore, it's hard to say if this is a significant problem when eating a normal meal which might, at most, contain about 10 mg of iron. However, just a cup of tea can, conversely, 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.

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 2013), 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.

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, 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, a USP expert committee voted in June 2007 to require the following cautionary statement to appear on the labels for green tea extracts: Caution: Must take with a meal. In rare cases extracts from green tea have been reported to adversely affect the liver. Discontinue use and consult a healthcare practitioner if you have a liver disorder or develop symptoms of liver trouble, such as abdominal pain, dark urine, or jaundice. However, approval of the label requirement was deferred and, in April 2009, the USP announced that the proposed requirement was cancelled. According to a USP spokesperson contacted by ConsumerLab.com, monitoring of adverse event databases from June 2007 through February 2009 showed no additional reports of liver toxicity, but the USP continues to monitor the safety of green tea. However, it may be wise to follow the original proposed guidance to take green tea extract with a meal, as this was given some support from tests on dogs which 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).

Information on this site is provided for informational purposes only. It is not an endorsement of any product nor it 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.


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