Green tea extract (EGCG)
Summary
Green tea extract concentrates the catechins in tea, chiefly EGCG. Pooled trials show small drops in total and LDL cholesterol, but no meaningful weight loss in trials outside Japan. In a year-long trial of high-dose extract, liver enzymes rose and about 5% of women developed liver-test abnormalities. NCCIH reports no safety concerns for green tea drunk as a beverage by adults.
Key facts
- A concentrate of green tea catechins, typically standardized to EGCG; many extracts also contain caffeine[1]
- About 7 mg/dL lower total and 2 mg/dL lower LDL cholesterol in 14 trials (1,136 adults); HDL unchanged[2]
- No meaningful weight loss in 6 trials outside Japan (532 adults); Japanese trials could not be pooled[3]
- About 2 mm Hg lower systolic pressure across 13 trials[4]
- Case reports link extract EGCG intakes of 140 to about 1,000 mg/day to liver injury; USP requires a take-with-food caution on extract monographs[6]
- 3 graded human outcomes on this page
- October 11, 2026
How it works
ProposedEGCG and other catechins are polyphenols; proposed effects on lipids include reduced intestinal cholesterol absorption. Fasting bolus doses raise EGCG exposure, which is linked to liver toxicity in animal and human reports.[6][2]
What the human research says
Human trials only, one row per outcome. The form column shows what each trial actually tested. Grades follow our evidence-grading policy.
At a glance: strongest evidence per outcome
| Outcome | Grade | Effect | Strongest evidence | Rows |
|---|---|---|---|---|
| Cholesterol | Grade B | Improved | Meta-analysis of 14 trials · n = 1,136 · 2011 | 1 row |
| Liver safety | Grade B | Worsened | RCT · n = 1,021 · 2017 | 1 row |
| Weight | No effect | No effect | Systematic review of 6 trials · n = 532 · 2012 | 1 row |
Every graded row
| Outcome | Effect | Grade | Best evidence | PMID |
|---|---|---|---|---|
| Total and LDL cholesterol | Improved | Grade B | Meta-analysis · n = 1,136 · 2011 Adults in 14 randomized trials of green tea beverages or extracts Form: Green tea beverage or extract · Dose: Varied across trials · Duration: Varied across trials Total cholesterol fell 7.2 mg/dL and LDL 2.2 mg/dL versus control; HDL did not change. | 21715508 (opens PubMed)Source [2] |
| Liver enzyme elevation (harm) | Worsened | Grade B | RCT · n = 1,021 · 2017 Postmenopausal women with normal baseline liver enzymes (Minnesota Green Tea Trial) Form: Decaffeinated green tea extract capsules · Dose: High-dose extract daily providing 843 mg EGCG/day · Duration: 12 months ALT rose 5.4 U/L more than placebo; 5.1% of women on extract developed moderate or worse liver-test abnormalities (odds ratio 7.0), which resolved on stopping and recurred on rechallenge. | 28765194 (opens PubMed)Source [5] |
| Body weight in overweight or obese adults | No effect | No effect | Systematic review · n = 532 · 2012 Overweight or obese adults in 6 trials conducted outside Japan Form: Green tea preparations · Dose: Varied across trials · Duration: 12–13 weeks Weight change versus control was −0.04 kg (95% CI −0.5 to 0.4); Japanese trials (1,030 adults) showed −0.2 to −3.5 kg but could not be pooled. | 23235664 (opens PubMed)Source [3] |
Forms
| Form | Elemental % | Absorption (human data) | GI tolerance | Studied for |
|---|---|---|---|---|
| Green tea extract standardized to EGCG | Varies | Taking bolus doses while fasting raises EGCG exposure compared with taking it with food.[6] | Nausea, constipation, abdominal discomfort and raised blood pressure are reported; rare liver injury.[1] | Cholesterol, weight and liver-safety trials |
| Brewed green tea | Varies | No head-to-head human absorption data in the sources cited here. | No safety concerns reported for adults drinking green tea, apart from its caffeine.[1] | Pooled with extracts in cholesterol trials |
Studied doses
Doses studied in human trials ranged from cups of brewed tea to extracts providing 843 mg of EGCG per day for 12 months; liver case reports involve 140 to about 1,000 mg of EGCG per day from extracts.[7][5][6][2]
Interactions
Published interactions only: each row cites a source. No row means none was found in our sources, not that a combination is safe.
Medicines
- NadololNIH fact sheetHigh intake of green tea lowered blood levels of this beta-blocker, which can reduce its effect.[1]
- AtorvastatinNIH fact sheetGreen tea extract can reduce blood levels of atorvastatin.[1]
- RaloxifeneNIH fact sheetCo-consuming green tea lowered raloxifene exposure in an NCCIH-funded study.[1]
Who should be careful
- Liver disease
- USP-required label wording: do not use with a liver problem, and stop if signs such as dark urine, abdominal pain or yellow skin appear.[6]
- Taking extract on an empty stomach
- Fasting bolus doses raise EGCG exposure; USP labels say to take with food.[6]
- Pregnancy and breastfeeding
- Green tea is a caffeine source; caffeine intake in pregnancy should stay moderate.[1]
- People on interacting medicines
- Nadolol, atorvastatin and raloxifene levels can fall with green tea.[1]
Talk to your pharmacist or clinician before starting a supplement, especially if you take prescription medicines.
Liver injury from extracts
- How often
- In a 1-year trial, about 1 in 20 women on high-dose extract developed liver-test abnormalities.[5]
Where to buy Green tea extract (EGCG)
Products from brands we partner with that contain Green tea extract (EGCG). Listing a product is not a claim that it works; check the amount per serving against the doses studied above, and the label for other ingredients.
- SupersmartPaid linkEGCG2 capsules: 455 mg EGCG (green tea extract standardized to 70% EGCG); 30 servings. This is about half the 843 mg/day that raised liver enzymes in a year-long trial but inside the 140–1,000 mg/day range seen in liver case reports; take with food and not with a liver condition.Shop at Supersmart (opens in new tab)Price and label checked 2026-10-11 on the brand’s site.
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Frequently asked questions
Does green tea extract help weight loss?
Not meaningfully outside Japan: a Cochrane review found −0.04 kg versus control in 6 trials of 532 adults.[3]
Does green tea lower cholesterol?
Slightly: about 7 mg/dL lower total cholesterol and 2 mg/dL lower LDL across 14 trials.[2]
Is green tea extract bad for the liver?
High-dose extract raised liver enzymes in a 1-year trial, and case reports link extracts to liver injury; brewed tea has no reported safety concerns in adults.[5][1]
How much EGCG is in a cup of tea versus a capsule?
Capsules are concentrated: liver case reports involve 140 to about 1,000 mg EGCG a day from extracts, far more than typical tea drinking.[6]
Does green tea extract interact with medicines?
Yes: it can lower blood levels of nadolol, atorvastatin and raloxifene.[1]
Sources
- [1]Green Tea: Usefulness and Safety (last updated February 2025). National Center for Complementary and Integrative Health, 2025. fact-sheet
- [2]Green tea intake lowers fasting serum total and LDL cholesterol in adults: a meta-analysis of 14 randomized controlled trials. Am J Clin Nutr, 2011. meta-analysis
- [3]Green tea for weight loss and weight maintenance in overweight or obese adults. Cochrane Database Syst Rev, 2012. systematic-review
- [4]Green tea catechins and blood pressure: a systematic review and meta-analysis of randomised controlled trials. Eur J Nutr, 2014. meta-analysis
- [5]Effect of Green Tea Supplements on Liver Enzyme Elevation: Results from a Randomized Intervention Study in the United States. Cancer Prev Res (Phila), 2017. RCT
- [6]United States Pharmacopeia (USP) comprehensive review of the hepatotoxicity of green tea extracts. Toxicol Rep, 2020. review
- [7]The safety of green tea extract supplementation in postmenopausal women at risk for breast cancer: results of the Minnesota Green Tea Trial. Food Chem Toxicol, 2015. RCT
What changed
- New monograph: definition, key facts, evidence table, studied doses, safety and FAQ written from the cited abstracts and fact sheets.
- Review: brewed-tea safety sentence reworded to match the NCCIH fact sheet.