herb · for weight & body composition
EGCG
Proposed to raise how much energy you burn — an effect that seems to need caffeine present too.
Say that in clinical terms
Catechins, especially EGCG, are proposed to increase energy expenditure and fat oxidation, partly by inhibiting the enzyme that breaks down noradrenaline - an effect that appears to depend on caffeine being present alongside the catechins.
How strong is the research?
Mixed evidence
A year of 400 mg a day in men: absorbed fine, tolerated fine, and no meaningful change.
3 papers read, 2 supporting, 1 against.
Tested as: green tea extract standardized to EGCG, 400-857 mg EGCG/day for 12 weeks to 1 year; the positive pooled effect in meta-analysis depended on catechins being combined with caffeine
How much to take
400–857 mg
Before you take it
- EFSA (2018) Scientific Opinion found that EGCG doses ≥800 mg/day from food supplements produce statistically significant increases in serum transaminases; EU Regulation 2022/2340 restricts single-portion EGCG content to <800 mg. No NIH/IOM Tolerable Upper Intake Level (UL) has been established for EGCG as a supplement; EFSA's 800 mg/day threshold is the most specific regulatory benchmark available.
- Drug-induced liver injury (DILI): EFSA reviewed 78+ case reports of liver injury linked to green tea extract supplements; risk is elevated with fasted intake and at high doses. UK Committee on Toxicity (COT) has independently reviewed and corroborated this evidence.
- CYP3A4 and P-glycoprotein inhibition: EGCG may elevate plasma concentrations of statins (atorvastatin, simvastatin), calcineurin inhibitors (cyclosporine, tacrolimus), and some calcium channel blockers.
- Non-heme iron absorption inhibition: EGCG significantly reduces non-heme iron absorption; caution is warranted in iron-deficient individuals and those with anemia.
- Antibiotic interaction: EGCG chelates fluoroquinolones and may reduce beta-lactam and tetracycline absorption; doses should be separated by at least 2h before or 4-6h after antibiotic administration per NIH ODS guidance.
- Mild antiplatelet activity: additive bleeding risk with warfarin or direct oral anticoagulants (DOACs).
- Contraindicated at supplemental doses during pregnancy: high-dose EGCG inhibits dihydrofolate reductase, impairing folate metabolism.
- Variable caffeine content: many green tea extracts retain caffeine; may exacerbate anxiety, hypertension, or arrhythmia in sensitive individuals.