RESEARCH MONOGRAPH · KDC-MN-196

EGCG (Epigallocatechin Gallate)

May 9, 2026 Kodiac biolabs Research Revised May 30, 2026 2 min read

Our opinion on this compound

73/100

The catechin everyone studies. Real effects in vitro, modest effects in humans, real liver risk at high doses

EGCG is the dominant catechin in green tea and probably the single most-studied polyphenol in the world. The literature is genuinely large, the mechanisms are interesting, and the human translation has been an exercise in disappointment for almost everyone who's gone in expecting miracles.

What's real: EGCG is a legitimate mitochondrial modulator and AMPK activator at achievable plasma concentrations, it has reasonable evidence for modest reductions in LDL cholesterol and blood pressure in meta-analyses, and the green tea extract preparations consistently produce small but reproducible metabolic effects in human trials. Body composition signal is real but small (a few percent at most over months). Cancer chemoprevention claims are mostly built on cell culture work at concentrations that humans can't achieve orally.

The mechanism story is interesting because EGCG genuinely is a promiscuous binder. It hits the proteasome, modulates several kinases, chelates iron, interferes with amyloid aggregation in vitro, and shows up as a positive hit in basically every screen because of its phenolic-rich structure. That's both a feature and a problem: pleiotropic effects are useful for chronic-disease research but make it hard to attribute any specific outcome to a specific mechanism.

Bioavailability is the persistent disappointment. Oral EGCG is around 0.1-2 percent bioavailable depending on formulation and timing, plasma half-life is 3-5 hours, and food coingestion significantly reduces absorption. Most positive trials use 300-800 mg/day green tea extract for 8-12 weeks. Below that you're probably just dosing astringency.

Where we get cautious: hepatotoxicity. High-dose green tea extract has produced real, idiosyncratic liver injury cases (the EFSA review in 2018 set 800 mg/day as the upper bound for concern), and EGCG appears to be the primary driver. This isn't a rare-anecdote issue, it's been documented in case series across multiple countries. Fasting state dosing seems to increase risk. Thats not the kind of thing you want to ignore for a polyphenol.

Sourcing-wise EGCG is heavily commoditized but adulteration with caffeine, other catechins, or just leaf powder is common at the low end. HPLC validation matters here more than for most polyphenols because purity claims of 98 percent are routinely false. Worth studying, just spec carefully and dont assume safety from the supplement positioning.

Evidence: 75
Mechanism: 78
Reliability: 68
Safety: 70
Sourcing: 70
Value: 75
Signal: 70
Staying power: 75

Plain-language summary Intrigue 60 / 100

EGCG is the principal catechin polyphenol in green tea. It has been studied extensively for cancer prevention, longevity, and metabolic effects. High-dose isolated EGCG carries some hepatotoxicity risk that whole green tea does not. Not stocked by Kodiac. This monograph is provided for research and educational reference.

Intrigue 0–100 blends mechanism novelty, evidence strength, and translational potential. Kodiac editorial, not peer-reviewed.

Tea catechin polyphenol

The principal catechin polyphenol of green tea with broad antioxidant and anti-inflammatory activity.

Abstract

EGCG (epigallocatechin-3-gallate; CAS 989-51-5; molecular formula C22H18O11; molecular weight 458.37) is the principal catechin polyphenol of green tea, accounting for 50 to 80 percent of total catechin content in unfermented tea. The compound has broad pharmacological activity: direct antioxidant, anti-inflammatory through NF-kB inhibition, modulation of multiple cancer-related pathways, and modest cardiovascular and metabolic effects. Bioavailability is poor; plasma EGCG concentrations after oral administration are low. Reported research dose ranges in the literature are described in the source publications. Hepatotoxicity has been reported with concentrated EGCG products at high doses (typically over 800 mg on an empty stomach), prompting EFSA dosing limits.

Mechanism of action

Direct antioxidant; NF-kB inhibition; multiple cancer-related pathway effects.

Reported research dose ranges

Reported research dose ranges in the literature.

References

Mereles D, Hunstein W. Epigallocatechin-3-gallate (EGCG) for clinical trials: more pitfalls than promises? Int J Mol Sci 2011.

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KDC-MN-196

The full reference document is provided strictly for research use only. It reports research dose ranges from the published literature, not instructions for use in humans or animals.

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FOR RESEARCH USE ONLY. Not for medical, diagnostic, or therapeutic purposes. Not for human consumption. All information is provided for research and educational purposes only.

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EGCG (Epigallocatechin Gallate)

Abstract

Mechanism of action

Reported research dose ranges

References

Read the full monograph

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Abstract

Mechanism of action

Reported research dose ranges

References

Read the full monograph

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