EGCG (Epigallocatechin Gallate · Metabolic · Antioxidant · Anticancer)

Compound	Epigallocatechin Gallate (EGCG; EGC-3-gallate; (-)-Epigallocatechin-3-O-gallate)
Chemical class	Polyphenol — Flavan-3-ol Gallate (catechin esterified with gallic acid at C-3; dominant green tea catechin)
CAS	989-51-5
Primary source	Camellia sinensis (green tea leaves — 50–70% of total catechin content)
Key applications	Metabolic / thermogenic; antioxidant; anticancer; neuroprotective; antiviral
Claim strength	Moderate
Typical form	EGCG 50% Powder (Green Tea Extract); EGCG ≥95% isolate; Green Tea Catechin Concentrate
Buy from Herbuno	EGCG 50% Powder (Green Tea Extract) | Standardized Camellia sinensis →

Name origin: EGCG stands for Epigallocatechin-3-Gallate — epigallocatechin (EGC; a galloyl B-ring catechin) esterified with gallic acid at the C-3 hydroxyl of the C-ring. The "epi" denotes C-3 stereochemistry; the "gallo" denotes the 3′,4′,5′-trihydroxy (pyrogallol) B-ring; the "-3-gallate" denotes the gallic acid ester. Traditional use: Green tea (Camellia sinensis) has been consumed in China and Japan for over 4,000 years — its medicinal properties attributed to its astringency, cooling nature, and mental clarity effects in traditional systems. Japanese matcha, which provides 3–5-fold higher EGCG than steeped green tea, emerged from Zen Buddhist monastic practice where sustained alertness without intoxication was valued. The specific identification of EGCG as the primary bioactive catechin came through 20th-century isolation chemistry. Research trajectory: EGCG is the most extensively studied single polyphenol in the world — with over 5,000 primary research papers. Key research domains include thermogenesis and weight management (EGCG-caffeine synergy via COMT inhibition), cancer biology (multiple cell line studies, limited clinical trials), cardiovascular protection, and neuroprotection. Despite its extensive preclinical evidence, clinical translation has been complicated by low bioavailability and the necessity of high doses for significant systemic effects. Commercial source: EGCG 50% Powder (standardised Green Tea Extract) is available from Herbuno — the most commercially accessible standardised EGCG preparation, delivering EGCG alongside ECG, EGC, and catechin in the natural green tea catechin distribution.

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Evidence for EGCG Applications

Metabolic / thermogenic: EGCG inhibits catechol-O-methyltransferase (COMT) — the enzyme that degrades norepinephrine — thereby extending norepinephrine's thermogenic beta-adrenergic signalling. In combination with caffeine (which stimulates norepinephrine release), EGCG produces synergistic thermogenesis. A meta-analysis of 11 RCTs (Hursel et al. 2009, Obesity Reviews) demonstrated 1.2–3.5 kg greater weight loss over 12 weeks for green tea catechin-caffeine versus control in overweight individuals. EGCG alone without caffeine shows reduced efficacy. Claim strength: Moderate.

Antioxidant: EGCG's pyrogallol B-ring (3′,4′,5′-trihydroxy) and galloyl ester at C-3 create one of the highest radical scavenging capacities of any dietary polyphenol — ORAC values for EGCG are 25–50-fold higher than vitamin C on a molar basis. Metal chelation (iron, copper) prevents Fenton chemistry. Plasma antioxidant capacity increases measurably within 1–2 hours of EGCG consumption, though absolute bioavailability is low (~1–5% of oral dose reaches systemic circulation). Claim strength: Moderate.

Anticancer research: EGCG inhibits cancer cell growth across virtually every cell line tested — via EGFR/HER2 receptor inhibition, PI3K/Akt/mTOR pathway suppression, proteasome inhibition, and Nrf2 activation. Clinical trials have been conducted for prostate, colorectal, and breast cancer — most showing modest or non-significant effects on primary endpoints, though some phase II trials show prevention activity in high-risk populations (prostate intraepithelial neoplasia, oral leukoplakia). Human evidence remains insufficient for any cancer treatment claim. Claim strength: Emerging (clinical); Moderate (preclinical).

Neuroprotective and antiviral: EGCG inhibits α-synuclein and β-amyloid aggregation in vitro — relevant to Parkinson's and Alzheimer's disease research. Antiviral activity against SARS-CoV-2, influenza, and HSV via spike protein binding and neuraminidase inhibition has been characterised. These remain preclinical findings. Claim strength: Emerging.

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Dosage & Formulator Specification

Clinical studies demonstrating metabolic and cardiovascular effects have used 200–800 mg/day EGCG (as standardised green tea extract providing equivalent EGCG). For thermogenesis, the EGCG-caffeine combination (270–300 mg EGCG + 80–150 mg caffeine per serving) is the evidence-based specification. For standalone EGCG without caffeine, higher doses (400–800 mg/day) are needed for equivalent metabolic effect. Cancer prevention studies have used 400–800 mg EGCG twice daily (800–1600 mg/day total).

EGCG 50% Green Tea Extract from Herbuno delivers 500 mg EGCG per gram of extract. A typical serving of 400 mg extract provides 200 mg EGCG alongside ~60 mg ECG, ~40 mg EGC, and ~20 mg catechin. For high-dose applications requiring ≥400 mg EGCG per serving, EGCG ≥95% isolate is available from specialty green tea fractionation suppliers.

Bioavailability is EGCG's critical limitation: oral bioavailability averages 1–5%, with large inter-individual variability. Strategies to improve absorption: fasting-state administration (food reduces Cmax by ~60–70%); milk-free ingestion (milk proteins form complexes with catechins reducing absorption); phospholipid complexation (Green Tea Phytosome — 5-fold bioavailability improvement demonstrated in pharmacokinetic studies); piperine co-administration (modest improvement via P-gp inhibition). Enteric-coated preparations reduce GI side effects at high doses.

High-dose EGCG (>800 mg/day) has been associated with hepatotoxicity in rare case reports and in isolated clinical trial participants — attributed to catechin-induced oxidative stress in susceptible individuals, particularly on empty stomach. EU botanical safety guidance recommends ≤800 mg EGCG/day from supplements with food. Formulators should include appropriate cautionary labelling for high-dose single-catechin products.

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Frequently Asked Questions — EGCG

Why is EGCG the dominant catechin in green tea but not oolong or black tea?
EGCG is enzymatically oxidised during tea fermentation. Green tea is unfermented (leaves immediately steamed or pan-fired after harvest), preserving EGCG content (50–70% of total catechins). Oolong tea is partially fermented, converting some EGCG to theaflavins and thearubigins. Black tea is fully fermented, converting most EGCG to theaflavins (dimers) and thearubigins (polymers). The theaflavins and thearubigins have their own bioactivity profiles but are structurally and pharmacologically distinct from EGCG.

What is COMT and why is its inhibition by EGCG important for thermogenesis?
Catechol-O-methyltransferase (COMT) is an enzyme that methylates and inactivates catecholamines including norepinephrine (NE). In brown adipose tissue and skeletal muscle, NE activates beta-3 adrenoceptors to increase thermogenesis and lipolysis. Caffeine stimulates NE release; EGCG inhibits COMT, prolonging NE's effect. This synergy explains why green tea extract (EGCG + caffeine) is consistently more effective for thermogenesis than decaffeinated EGCG preparations in clinical comparisons.

Is EGCG effective for weight loss as a standalone supplement without caffeine?
Without caffeine, EGCG's thermogenic efficacy is substantially reduced. Meta-analyses comparing caffeine-containing versus caffeine-free green tea catechin preparations consistently show greater weight loss for the combined preparation. Decaffeinated EGCG supplements at standard doses produce modest-to-no significant weight reduction in most RCTs. For weight management positioning, the full catechin-caffeine green tea matrix or explicit EGCG + caffeine co-formulation is the evidence-based approach.

What hepatotoxicity risk should formulators account for with high-dose EGCG?
Case reports of liver injury associated with concentrated green tea extract supplements exist — primarily with products providing >700–1000 mg EGCG/day, often taken fasted. The European Food Safety Authority (EFSA) 2018 opinion concluded that EGCG from food supplements can cause hepatotoxic effects, particularly above 800 mg/day, and recommended caution. Regulatory guidance (EU, Australia) now requires appropriate risk communication on products delivering high-dose isolated EGCG. At standard supplement doses (200–400 mg EGCG/day with food), the risk is considered low for healthy adults.

Related compounds: Epicatechin, Catechin, Epicatechin Gallate, Gallocatechin

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Claim-strength scale – High = multiple human RCTs; Moderate = limited trials or strong preclinical convergence; Emerging = early-stage lab or animal data.

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