Dietary (−)-Epigallocatechin Gallate (EGCG): State-of-the-Art Advances in Bioactivities, Bioavailability Enhancement Strategies, and Applications in Nutrition and Health

(-)-Epigallocatechin gallate (EGCG), a major polyphenolic compound in tea leaves, exhibits potent antioxidant, anti-inflammatory, and anticancer properties. Despite its therapeutic potential, poor bioavailability limits clinical efficacy. This review comprehensively examines the sources, and multifunctional bioactivities of EGCG, including its antioxidant, anti-inflammatory, anticancer, cardiovascular protective, metabolic regulatory, neuroprotective, gut microbiota-modulating, and antimicrobial properties. Traditional and emerging applications of EGCG are summarized from different perspectives. Strategies to enhance bioavailability such as nanotechnology, chemical modification, and combination drug regimens are highlighted. Based on existing human clinical trials, recommendations for effective and safe dosage ranges of EGCG intake are provided. By analyzing the current situation, providing reasonable opinions and making outlooks, the clinical value of EGCG will be fully released, which will ultimately promote human health.