Summary
What is green tea?
Green tea is made by lightly steaming freshly cut leaves of Camellia sinensis. It is higher in antioxidant catechins (polyphenols) such as EGCG than black tea. It is sold in many forms such as tea bags, loose leaf 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 (only about 9 mg per serving) in two products, which were, therefore, Not Approved for quality by ConsumerLab. All other products had higher levels (29 mg to 118 mg per serving). Supplements (sold as capsules) provided an enormous range of EGCG — from just 40 mg to 470 mg per serving.
Our tests for caffeine found 1 to 8 mg in decaffeinated teas and 17 mg to 56 mg in other teas made from about 2 grams of tea leaf.
Which is the best green tea?
We chose Top Picks in several categories. Our Top Picks among green tea in tea bags stood out for having great flavor and high amounts of EGCG at modest cost. Our Top Pick for ceremonial matcha powder costs just 1/3 the price of another matcha powder and provides the same high-dose of EGCG. We tested and Approved two loose leaf teas but we don't consider either a Top Pick. We chose moderate-strength and high-strength Top Picks among green tea supplements.
Heavy metals in green tea?
Green tea leaves can accumulate toxic lead and arsenic, but most products had little to none. Even those containing the highest amounts are unlikely to pose a health risk to adults, but pregnant women may wish to avoid them.
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. Green tea contains a small amount of fluoride and regularly consuming very large amounts of green tea can cause fluorosis, a condition that makes bones and teeth brittle. Avoid excessive green tea when pregnant. Don't drink very hot tea, as this has been associated with higher risk of gastric cancer (see Concerns and Cautions). Be aware that plastic (nylon) tea bags may release microplastics as well as reduce levels of EGCG in tea, and some tea bags are heat sealed with plastic — we identified which tea bags, by brand, contain plastic and which do not (See ConsumerTips).
