GradedHealth

Is green tea good for your health? What matcha and green tea trials show

Pooled trials show small drops in weight and blood pressure with green tea. Concentrated extracts may raise liver enzymes. We found no matcha trials.

Published October 2026

Short answer

Small effects on weight and blood pressure; the health-outcome evidence is observational; concentrated extracts may raise liver enzymes. Evidence grade C (Limited). Umbrella review and trial meta-analyses show small effects; death-risk data are observational and mixed; liver and iron findings are indirect (extracts, black tea), so downgraded for indirectness and inconsistency.

Key takeaways

  • An umbrella review of 13 meta-analyses found green tea lowered weight by about 0.9 kg and waist size by about 1 cm [1].
  • Adding green tea to exercise gave a small extra weight loss over exercise alone, which the authors call minimal [2].
  • Blood pressure fell by about 1 mmHg in the same umbrella review, while a meta-analysis of camellia and herbal tea trials found no effect on total cholesterol [1][3].
  • Observational cohorts link green tea drinking to lower death rates, but the results differ by cause and sex, and cohorts cannot prove cause [4][5].
  • In one trial, a high-dose extract raised liver enzymes more in postmenopausal women with one gene variant, and case reports link liver injury to EGCG intakes from 140 mg to about 1,000 mg a day [6][7].

The short version

Pooled trials of green tea show small drops in weight and blood pressure [1]. Adding it to exercise gave a small extra weight loss in overweight adults [2]. Studies linking green tea to lower death rates are observational and cannot show cause [4][5]. In one trial, a high-dose extract raised liver enzymes more in women with a certain gene variant [6].

What the studies show

Weight. An umbrella review, which pools other meta-analyses, combined 13 meta-analyses and found green tea lowered weight by about 0.9 kg and waist size by about 1 cm [1]. In a 2024 meta-analysis of 10 randomised trials in overweight or obese adults, green tea with exercise lowered weight and body fat more than exercise with placebo, but added no benefit to cholesterol [2].

In a placebo-controlled trial of 102 women with central obesity, about 857 mg of EGCG a day for 12 weeks was followed by a weight fall from 76.8 kg to 75.7 kg within the treatment group [8]. The abstract reports that within-group change and does not give the difference from placebo [8]. In an 8-week trial of 30 overweight women, 500 mg a day of green tea extract added to endurance training cut body weight and body fat more than training with placebo [9].

Blood pressure. The umbrella review found systolic and diastolic blood pressure each fell by about 1 mmHg [1]. The authors say the effects depend on how much is drunk, health status and lifestyle [1].

Cholesterol. The umbrella review found total and LDL cholesterol lower in pooled analysis [1]. A 2022 meta-analysis of camellia and herbal tea trials in people with type 2 diabetes found no effect on total cholesterol [3]. The two results do not agree.

Death. Two Shanghai cohorts with 6,517 deaths linked green tea drinking to lower cardiovascular death (hazard ratio 0.86) but not to lower all-cause death (hazard ratio 0.95, not statistically significant) [4]. Cancer death was not linked to green tea [4]. A Vietnamese cohort of 42,146 people found lower all-cause death with more green tea, per standard-deviation rise in intake (hazard ratio 0.93), seen in men but not in women [5]. In the UK Biobank, where black tea is the main type, two or more cups of tea a day were linked to lower all-cause death [10].

The nuances

Forms. The trials we read used concentrated extracts, not brewed tea [8][9]. We found no matcha trial. A 2017 systematic review found that daily green tea with 100 to 460 mg of EGCG a day gave the greater reductions in body fat and body weight in trials of 12 weeks or more [11].

Caffeine. Green tea contains caffeine, and researchers are concerned about excess caffeine among heavy green tea drinkers [5]. A 2017 systematic review found that up to 400 mg of caffeine a day is generally not linked to overt adverse effects in healthy adults [12].

Iron. Tea with meals can reduce iron absorption. The study we found tested black tea, not green tea: in 20 young Indian women, one or two cups of black tea with a rice meal cut iron absorption by 49% to 67% [13]. We found no green tea study of iron.

Liver. The main green tea catechin is EGCG [6]. In the Minnesota Green Tea Trial of 1,075 postmenopausal women, 400 took 843 mg of EGCG a day for 12 months. In that group, ALT, a liver enzyme, rose by about 78% at six months in women with one gene variant, against about 28% in women with the other [6]. The authors say the variant may be an important risk factor for clinically relevant rises in liver enzymes. The abstract gives no placebo comparison for these figures [6]. Case reports link liver injury to EGCG intakes from 140 mg to about 1,000 mg a day [7]. The U.S. Pharmacopeia review that reports this discloses that some authors work for supplement and ingredient companies [7].

Medicines. A 2014 review found a clinical drug study showed a small rise in levels only for drugs cleared by CYP3A4, which it judged clinically irrelevant. It also concluded that the published case reports give no clinical evidence that green tea extract raises the risk of drug-induced liver injury, and that only a few of those cases involved other drugs [14].

What this means for you

The studies describe small effects on weight and blood pressure, so green tea should not replace a treatment a doctor has advised. If you have a liver problem, the U.S. Pharmacopeia label for powdered green tea extract advises not to use it, and to speak to a healthcare practitioner if you notice symptoms of liver trouble such as dark urine or jaundice. The same label advises taking it with food, not on an empty stomach [7]. Talk to a doctor before taking extracts if you take medicines or are pregnant. We found no studies of green tea itself in pregnancy. For caffeine, a 2017 review found up to 300 mg a day generally not linked to adverse reproductive effects in pregnant women [12]. The 102-woman trial reported no side effects or adverse events over 12 weeks [8]. We found no studies of green tea in kidney disease or breastfeeding.

Go deeper

  • Green Tea — Small drops in weight and blood pressure in trials, with a small extra weight loss when combined with exercise.

References

  1. A comprehensive overview on the effects of green tea on anthropometric measures, blood pressure, glycemic and lipidemic status: An umbrella review and meta meta-analysis study.. Nutr Metab Cardiovasc Dis, 2022.
  2. Does green tea catechin enhance weight-loss effect of exercise training in overweight and obese individuals? a systematic review and meta-analysis of randomized trials.. J Int Soc Sports Nutr, 2024.
  3. Effects of Camellia tea and herbal tea on cardiometabolic risk in patients with type 2 diabetes mellitus: A systematic review and meta-analysis of randomized controlled trials.. Phytother Res, 2022.
  4. Green tea consumption and cause-specific mortality: Results from two prospective cohort studies in China.. J Epidemiol, 2017.
  5. Green Tea Consumption and Risk of All-Cause Mortality: Findings from a Prospective Cohort Study.. Nutrients, 2026.
  6. Hepatotoxicity with High-Dose Green Tea Extract: Effect of Catechol-O-Methyltransferase and Uridine 5'-Diphospho-glucuronosyltransferase 1A4 Genotypes.. J Diet Suppl, 2023.
  7. United States Pharmacopeia (USP) comprehensive review of the hepatotoxicity of green tea extracts.. Toxicol Rep, 2020.
  8. Therapeutic effect of high-dose green tea extract on weight reduction: A randomized, double-blind, placebo-controlled clinical trial.. Clin Nutr, 2016.
  9. Does green tea extract enhance the anti-inflammatory effects of exercise on fat loss?. Br J Clin Pharmacol, 2020.
  10. Tea Consumption and All-Cause and Cause-Specific Mortality in the UK Biobank : A Prospective Cohort Study.. Ann Intern Med, 2022.
  11. [Effects of green tea and its epigallocatechin (EGCG) content on body weight and fat mass in humans: a systematic review].. Nutr Hosp, 2017.
  12. Systematic review of the potential adverse effects of caffeine consumption in healthy adults, pregnant women, adolescents, and children.. Food Chem Toxicol, 2017.
  13. Iron absorption in young Indian women: the interaction of iron status with the influence of tea and ascorbic acid.. Am J Clin Nutr, 2008.
  14. Green tea extract and the risk of drug-induced liver injury.. Expert Opin Drug Metab Toxicol, 2014.