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Green tea extract

A Cochrane review found green tea preparations outside Japan changed weight by 0.04 kg. LDL cholesterol and blood pressure fell by small amounts. EFSA found that 800 mg or more of EGCG a day as a supplement raised liver enzymes in trials. US network data link green tea to 3% of adjudicated liver injury cases, some needing transplant.

Add to Bio HackChecked 2026-11-09
Status
Dietary supplement in the US. The United States Pharmacopeia monograph for powdered decaffeinated green tea extract carries a cautionary liver label.
Also called
EGCG, epigallocatechin gallate, green tea catechins, Camellia sinensis extract, decaffeinated green tea extract, GTE, fat burner
Taken for
fat loss, weight loss, metabolism, fat burning, cholesterol, blood pressure, blood sugar, antioxidant, energy, fibroids

Strong several reviews agree · Moderate one review or consistent trials · Limited one or a few small studies · Untested no study in people, listed with what it rests on

Shown to help5

Reported risks5

What people take it for, and what was found

Shown to help5

Strong

LDL cholesterol

Shown to lower LDL cholesterol slightly, about 2 mg/dL, and total cholesterol about 7 mg/dL in adults, with no HDL change.

The numbers and sources
Effect
Across 14 RCTs (1,136 subjects), green tea beverages or extracts lowered total cholesterol by 7.20 mg/dL (95% CI -8.19 to -6.21) and LDL cholesterol by 2.19 mg/dL (95% CI -3.16 to -1.21). HDL did not change [3]. Across 13 studies, LDL fell by 0.16 mmol/L (95% CI -0.22 to -0.09) [4].
Population
Adults in RCTs [3][4].
Sources
[3], [4]
Caveats
Both reviews pooled beverages with extracts.
Moderate

Blood pressure

Shown to lower blood pressure about 2 mmHg in adults, more with extracts and in those starting at 130 mmHg or higher.

The numbers and sources
Effect
Across 13 studies, green tea lowered systolic pressure by 2.08 mmHg (95% CI -3.06 to -1.05) and diastolic by 1.71 mmHg (95% CI -2.86 to -0.56). Reductions were larger with baseline systolic pressure of 130 mmHg or more and with extracts [4].
Population
Adults in RCTs from 1995 to 2013 [4].
Sources
[4]
Caveats
One meta-analysis.
Moderate

Fat burning during exercise

Shown to raise fat burning slightly during and after exercise. These trials did not measure body fat.

The numbers and sources
Effect
In a 2026 GRADE-assessed meta-analysis of 9 trials, green tea extract raised fat oxidation during exercise by 0.2 g per minute (95% CI 0.04 to 0.36) and after exercise by 0.04 g per minute (95% CI 0.01 to 0.08). Carbohydrate oxidation fell after exercise (-0.16 g per minute) and did not change during it [5].
Population
Participants in 9 randomized trials measuring substrate use around exercise [5].
Sources
[5]
Caveats
One meta-analysis, with certainty rated low to high depending on the outcome [5]. Fat oxidation rate is not fat loss, and these trials did not measure body fat.
Moderate

Blood sugar

Shown to lower fasting glucose, HbA1c and insulin resistance modestly with EGCG supplements in adults, with HbA1c down about 0.18 points.

The numbers and sources
Effect
In a 2025 meta-analysis of 41 RCTs, EGCG supplements lowered fasting glucose, HbA1c and HOMA-IR by modest amounts. HbA1c fell 0.18 percentage points (95% CI -0.35 to -0.02), and fasting insulin did not change significantly (95% CI -1.46 to 0.47) [6].
Population
Adults in 41 RCTs of EGCG [6].
Sources
[6]
Caveats
The authors describe the HbA1c and insulin effects as modest and possibly not clinically meaningful for most people [6].
LimitedStudied in women

Fibroid size and heavy bleeding

One small trial found green tea extract shrank fibroids by about a third over 4 months in women with symptomatic fibroids. An uncontrolled study found no size change.

Compared with placebo capsules of brown rice [13]; before treatment, in the same women [14][15]

The numbers and sources
Effect
In a placebo-controlled trial, 800 mg a day of green tea extract (45% EGCG) for 4 months reduced total fibroid volume by 32.6%, while volume rose 24.3% on placebo (P 0.0001). Fibroid symptom severity fell 32.4% and quality of life rose 18.53% against placebo. In the green tea group, hemoglobin rose 0.7 g/dL (P 0.02) and average blood loss fell from 71 to 45 mL a month (P 0.001). No adverse effects or endometrial changes were seen in either group [13]. In 25 women who took green tea extract capsules for 6 months with no control group, fibroid size, symptom scores and laboratory values did not change, while the physical score of a quality of life questionnaire rose [14]. In 16 premenopausal women over 40 given 300 mg of EGCG with vitamin D and vitamin B6 for 90 days, mean fibroid size fell 17.8% and bleeding lasted 0.9 days less, with no change in flow intensity [15].
Population
39 women aged 18 to 50 with symptomatic fibroids, 33 of them analyzed [13]; 25 women, median age 45, with few or no fibroid symptoms [14]; 16 women over 40 with fibroids [15].
Sources
[13], [14], [15]
Caveats
One small trial, with 11 women finishing on placebo [13]. The hemoglobin and blood loss changes are reported within the green tea group, not as differences from placebo [13]. [14] and [15] had no control group, and [15] combined EGCG with vitamin D and vitamin B6. The trial dose supplies about 360 mg of EGCG a day [13], within the 140 to about 1,000 mg range in liver injury case reports [8].

Mixed results1

Moderate

Weight loss

Mixed results: trials outside Japan found no weight change, while Japanese trials and an earlier review found losses of about 0.2 to 3.5 kg.

The numbers and sources
Effect
In 6 studies outside Japan (532 participants), weight change differed from control by -0.04 kg (95% CI -0.5 to 0.4). Eight Japanese studies (1,030 participants) could not be pooled and ranged from -0.2 to -3.5 kg [1]. An earlier meta-analysis of 11 articles found catechins lowered body weight by 1.31 kg, with -0.82 kg in Caucasian and -1.51 kg in Asian participants [2].
Population
Overweight or obese adults in trials of 12 to 13 weeks [1]; weight loss and maintenance studies [2].
Sources
[1], [2]
Caveats
The two reviews disagree. The Cochrane review required at least 12 weeks and analyzed Japanese and non-Japanese trials separately [1].

Doses studied

Supplements provide 5 to 1,000 mg of EGCG a day, while green tea infusions supply a mean 90 to 300 mg a day and up to 866 mg in high-level drinkers in the EU [7]. Liver injury case reports involve 140 mg to about 1,000 mg of EGCG a day [8].

Risks

Reported risks5

ModerateHow often is not known

Raised liver enzymes at high EGCG doses

EFSA's panel concluded that trials show 800 mg or more of EGCG a day as a supplement raises liver enzymes compared with control.

The numbers and sources
How common
How often is not known: the sources give no rate.
Effect
EFSA's panel concluded that interventional trials show 800 mg or more of EGCG a day taken as a supplement produced a statistically significant rise in serum transaminases compared with control [7]. A systematic review of 34 RCTs found liver-related adverse events in 7 people on green tea extract and 1 on control (OR 2.1, 95% CI 0.5 to 9.8), mostly mild enzyme rises [9].
Population
Adults in green tea extract trials [7][9].
Sources
[7], [9]
Caveats
Trial-based rates are small and imprecise. The trial review searched to December 2013 [9].
ModerateHow often is not known

Liver injury

Linked to 3% of US registry liver injury cases, 35% of them severe, with 3 needing transplants. USP linked injury to 140 to about 1,000 mg EGCG a day.

The numbers and sources
How common
How often is not known: the sources give no rate.
Effect
Of 1,414 adjudicated cases in the US Drug-Induced Liver Injury Network, 40 (3%) were attributed to green tea. Injury was hepatocellular in 95%, 83% were jaundiced, 35% were severe, and 3 (8%) needed a liver transplant. Injury recurred in 3 people on re-exposure. HLA-B*35:01 was found in 72% of green tea cases versus 11% of population controls [10]. A USP review found hepatotoxicity associated with 140 to about 1,000 mg of EGCG a day, higher catechin bioavailability with bolus doses taken fasting, and no evidence that contaminants caused the injury [8].
Population
US registry cases [10]; systematic review of case reports, animal and human data [8].
Sources
[8], [10]
Caveats
Green tea is a frequent component of implicated multi-ingredient products [10]. EFSA also notes rare liver injury after traditional green tea infusions [7].
LimitedHow often is not known

Pancreatitis with suspected liver injury

Case reports: a woman taking only water and green tea catechin supplements for 2 weeks developed severe pancreatitis and suspected toxic hepatitis.

The numbers and sources
How common
How often is not known: the sources give no rate.
Effect
A 36-year-old woman who took only water and green tea catechin supplements for 2 weeks developed severe acute pancreatitis with highly raised liver and pancreatic enzymes and suspected toxic hepatitis. She recovered and left hospital after 15 days [11].
Population
One case report [11].
Sources
[11]
Caveats
One case. She had eaten no food for the 2 weeks, and the abstract does not name the product or dose [11].
LimitedHow often is not known

Interaction with nadolol

One small study found brewed green tea cut blood levels of the beta-blocker nadolol by about 85% in healthy adults.

The numbers and sources
How common
How often is not known: the sources give no rate.
Effect
In 10 healthy volunteers, 14 days of green tea at 700 mL a day lowered the peak concentration and AUC of the beta-blocker nadolol by 85.3% and 85.0% and reduced its effect on systolic blood pressure [12].
Population
10 healthy adults [12].
Sources
[12]
Caveats
Brewed green tea, not extract. Other drugs were not tested.
LimitedHow often is not known

Labeling requirement

USP's monograph label warns not to take it on an empty stomach or with a liver problem, and to stop with symptoms such as dark urine or jaundice.

The numbers and sources
How common
How often is not known: the sources give no rate.
Effect
Based on its review, USP added a cautionary label to its powdered decaffeinated green tea extract monograph: do not take on an empty stomach, take with food, do not use with a liver problem, and stop and consult a practitioner with symptoms such as abdominal pain, dark urine or jaundice [8].
Population
Products that follow the USP monograph [8].
Sources
[8]
Caveats
USP is a standards body, not a regulator.

Claims tested and not found

  1. That green tea extract produces weight loss in trials outside Japan. Weight differed from control by -0.04 kg (95% CI -0.5 to 0.4) [1].
  2. That green tea raises HDL cholesterol. HDL did not change across 14 RCTs [3].

Sources

  1. Jurgens TM, Whelan AM, Killian L, et al. Green tea for weight loss and weight maintenance in overweight or obese adults. Cochrane Database of Systematic Reviews. 2012. https://doi.org/10.1002/14651858.CD008650.pub2
  2. Hursel R, Viechtbauer W, Westerterp-Plantenga MS. The effects of green tea on weight loss and weight maintenance: a meta-analysis. International Journal of Obesity. 2009. https://doi.org/10.1038/ijo.2009.135
  3. Zheng XX, Xu YL, Li SH, et al. Green tea intake lowers fasting serum total and LDL cholesterol in adults: a meta-analysis of 14 randomized controlled trials. American Journal of Clinical Nutrition. 2011. https://doi.org/10.3945/ajcn.110.010926
  4. Khalesi S, Sun J, Buys N, et al. Green tea catechins and blood pressure: a systematic review and meta-analysis of randomised controlled trials. European Journal of Nutrition. 2014. https://doi.org/10.1007/s00394-014-0720-1
  5. Khalilkhaneh AH, Bidsheki MV, Zebari SMS, et al. Effect of Green Tea Extract Supplementation on Substrate Utilization: A GRADE-Assessed Systematic Review and Dose-Response Meta Analysis of Randomized Controlled Trials. Nutrition Reviews. 2026. https://doi.org/10.1093/nutrit/nuag025
  6. Saadh MJ, Gataa IS, Hussam AS, et al. Effect of Epigallocatechin Gallate on Glycemic Index: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Clinical Therapeutics. 2025. https://doi.org/10.1016/j.clinthera.2025.07.015
  7. EFSA Panel on Food Additives and Nutrient Sources added to Food (ANS), Younes M, Aggett P, et al. Scientific opinion on the safety of green tea catechins. EFSA Journal. 2018. https://doi.org/10.2903/j.efsa.2018.5239
  8. Oketch-Rabah HA, Roe AL, Rider CV, et al. United States Pharmacopeia (USP) comprehensive review of the hepatotoxicity of green tea extracts. Toxicology Reports. 2020. https://doi.org/10.1016/j.toxrep.2020.02.008
  9. Isomura T, Suzuki S, Origasa H, et al. Liver-related safety assessment of green tea extracts in humans: a systematic review of randomized controlled trials. European Journal of Clinical Nutrition. 2016. https://doi.org/10.1038/ejcn.2016.78
  10. Hoofnagle JH, Bonkovsky HL, Phillips EJ, et al. HLA-B35:01 and Green Tea-Induced Liver Injury. Hepatology*. 2021. https://doi.org/10.1002/hep.31538
  11. Kim Y, Nho WY. Severe acute pancreatitis and toxic hepatitis after solitary dietary supplement ingestion: A case report. Medicine. 2026. https://doi.org/10.1097/MD.0000000000050060
  12. Misaka S, Yatabe J, Müller F, et al. Green Tea Ingestion Greatly Reduces Plasma Concentrations of Nadolol in Healthy Subjects. Clinical Pharmacology & Therapeutics. 2014. https://doi.org/10.1038/clpt.2013.241
  13. Roshdy E, Rajaratnam V, Maitra S, et al. Treatment of symptomatic uterine fibroids with green tea extract: a pilot randomized controlled clinical study. International Journal of Women's Health. 2013. https://doi.org/10.2147/ijwh.s41021
  14. Biro R, Richter R, Ortiz M, Sehouli J, David M. Effects of epigallocatechin gallate-enriched green tea extract capsules in uterine myomas: results of an observational study. Archives of Gynecology and Obstetrics. 2021. https://doi.org/10.1007/s00404-020-05907-6
  15. Grandi G, Del Savio MC, Melotti C, et al. Vitamin D and green tea extracts for the treatment of uterine fibroids in late reproductive life: a pilot, prospective, daily-diary based study. Gynecological Endocrinology. 2022. https://doi.org/10.1080/09513590.2021.1991909

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