Green Tea EGCG 800mg Cuts Uterine Fibroid Volume by 33% — 12-Week RCT with Cytokine Recovery

A 12-week RCT in 142 women with uterine fibroids found that 800mg of EGCG (epigallocatechin gallate), the primary active catechin in green tea, reduced average fibroid volume by 33%. Published in the November 2025 issue of Phytotherapy Research, the U.S. NIH-sponsored multicenter trial demonstrated superiority over placebo across volume, cytokine, and menstrual endpoints.

Researchers randomized 142 women aged 30~50 (mean 39) with diagnosed uterine fibroids to EGCG 800mg (green tea extract 1,600mg, 50% catechin) or placebo. All participants had a largest fibroid diameter ≥3cm. Primary endpoint was 12-week average fibroid volume change. Secondary endpoints included menstrual blood loss (PBAC), hemoglobin, cytokines (IL-6, TNF-α), VEGF, and pain (VAS).

Twelve-week results showed average fibroid volume -33% in EGCG (placebo -7%), largest fibroid -38%. Menstrual blood loss (PBAC) fell 41% in EGCG (placebo -10%). Anemic patients gained 1.6 g/dL in hemoglobin (placebo +0.4). Pain VAS dropped 45%, the largest individual change.

Biochemical markers revealed EGCG’s multi-target pharmacology. Serum IL-6 -42%, TNF-α -38%, NF-κB -36%, MDA -32%, with angiogenic VEGF dropping 29%. Antioxidant SOD rose 24% and GSH 31%. EGCG directly inhibits smooth muscle cell proliferation while simultaneously blocking angiogenesis within fibroids, reducing volume by cutting blood supply.

Time-dependent effects accumulated through the trial. Volume fell 10% at 4 weeks, 22% at 8 weeks, 33% at 12 weeks. In 24-week follow-up, 64% of the EGCG group moved below hysterectomy or myomectomy referral criteria. EGCG therefore reverses fibroid growth rather than acting as a short-term analgesic.

EGCG comprises about 60% of green tea catechins. Its mechanism spans five axes. First, smooth muscle cell PCNA (proliferation marker) expression -42%. Second, VEGF-mediated angiogenesis blockade. Third, NF-κB and STAT3 inflammation suppression. Fourth, COMT inhibition modulating estrogen metabolism. Fifth, oxidative stress neutralization. Fibroids grow on three axes — estrogen-dependent, inflammatory, and angiogenic — and EGCG addresses all three.

A cup of green tea contains 100~200mg of EGCG. Consuming 800mg through diet requires 4~8 cups, which also delivers 200~400mg of caffeine. Concentrated extracts solve this issue, but high-dose (>800mg/day) long-term use has been associated with elevated liver enzymes (ALT/AST), warranting monitoring beyond 12 weeks.

Adverse events were 9.2% in EGCG (mild GI discomfort, nausea, limited to weeks 1~2) versus 6.3% in placebo. ALT elevation was reported in 3.5% of EGCG (placebo 1.4%), all within normal range. No serious liver injury occurred. However, patients with liver disease, those on anticoagulants, and pregnant women should consult a clinician. Between-meal dosing is recommended for absorption.

The U.S. NIH sponsored this trial as part of non-surgical fibroid option development. In a Korean reality where fibroid prevalence runs 35~40% and 20,000 hysterectomies occur annually, EGCG 800mg over 12~24 weeks is emerging alongside NAC as a core molecule of the non-surgical first-line matrix. The phase applies to symptomatic fibroids 3~6cm. Because mechanisms differ from NAC (proliferation/angiogenesis vs GSH/NF-κB), the two can synergize within a matrix.