Green Tea Extract (EGCG)
- Effective dose
- 338 mg
- Evidence
- 2/5· Emerging
Last updated June 1, 2026
What it is
Green tea extract is a concentrated source of catechins, chiefly epigallocatechin gallate (EGCG), the polyphenol behind most of green tea's antioxidant activity. Concentrated bolus doses behave very differently from brewed tea, especially for liver safety.
Benefits
Green tea catechins provide antioxidant activity and modest, inconsistent effects on metabolic markers; a safe intake derived by USP for solid bolus products is up to 338 mg EGCG/day.
When to take it
Take with food, never on an empty stomach — fasting dramatically increases catechin absorption and liver-injury risk. Stop and seek care if symptoms of liver trouble (jaundice, dark urine, abdominal pain) appear.
Side effects
Concentrated extracts can cause rare but serious liver injury, with case reports spanning EGCG intakes of 140 mg to about 1,000 mg/day and large individual variability. Risk rises sharply when taken on an empty stomach.
Sources
Products containing Green Tea Extract (EGCG)
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