EGCG from Green Tea Extract for NAFLD and Metabolic Disorders: A Systematic Review for Therapeutic Efficacy of EGCG

Abstract

Epigallocatechin-3-gallate (EGCG), a prominent antioxidant catechin found in green tea extract (GTE), has gained considerable attention for its potential role in managing nonalcoholic fatty liver disease (NAFLD) and associated metabolic disorders. This systematic review evaluates findings from 120 clinical studies obtained thorough searches of major scientific databases including PubMed, Scopus, Web of Science, the Cochrane Library, Clinical Trials.gov, and Google Scholar. EGCG supplementation, typically delivered in doses between 300 to 800 mg per day over periods ranging from 8 to 24 weeks, was associated with significant improvements in liver biomarkers, insulin resistance, lipid metabolism, and body composition. Improvements were noted in liver enzyme levels (ALT, AST), HOMA-IR indices, body mass index (BMI), and circulating adipokines. EGCG also exhibited strong anti-inflammatory and antioxidant activity and therapeutically influenced gut microbiota, enhancing its metabolic outcomes. Most studies reported good tolerability, some adverse effects such as liver or kidney stress and mild digestive discomfort were observed, particularly with high dose or fasting regimens. These findings support the therapeutic potential of EGCG as a complementary strategy for NAFLD and metabolic syndrome management. Standardized, large scale human trials are needed to establish consistent dosing guidelines and long-term safety. A PRISMA diagram illustrating the study selection process is provided in the review.