Catechins / EGCG

What it is

Catechins are a family of plant polyphenols (a type of antioxidant compound) found abundantly in green tea. The most studied and most abundant is EGCG (epigallocatechin gallate). When people talk about green tea's antioxidant or metabolic effects, they're mostly referring to catechins — and EGCG in particular.

What it does

• Act as antioxidants in laboratory settings, neutralizing reactive molecules.
• May modestly influence metabolism. Catechins (often alongside caffeine) can slightly nudge fat oxidation and energy expenditure — but the effect on body weight in human studies is small and inconsistent.
• Are the marker for standardization. Green tea extract is often standardized to a percentage of EGCG, which is how you gauge its potency.

What it does NOT do

• They are not a proven "fat-burner." Marketing overstates a small, variable effect.
• Antioxidant activity in a test tube doesn't guarantee a clinical benefit, partly because EGCG has low oral bioavailability (much of it isn't absorbed).
• More is not safer. Concentrated EGCG carries a real, dose-related risk — see below.

Forms, doses, and safety

• Present in brewed green tea (generally safe) and, far more concentrated, in green tea extract supplements.
• Safety ceiling: EGCG intakes of 800 mg/day or more from supplements are associated with signs of liver stress; a clearly safe extract dose has not been established. Take extract with food, never on an empty stomach, which raises absorption and risk.
• Compare products by their EGCG content, not just total extract weight.

Sources

1. EFSA. Scientific opinion on the safety of green tea catechins. 2018.
2. Oketch-Rabah HA, et al. USP comprehensive review of the hepatotoxicity of green tea extracts. 2020.