Ingestion of green tea rapidly decreases prostaglandin E-2 levels in rectal mucosa in humans

The objective of this Phase VII study was to assess the potential for green tea to be used as a colorectal cancer chemopreventive agent. This study me asured the dose-related biological effects of administration of a single do se of green tea on the rectal mucosa of normal volunteers, Volunteers were admitted to the Robert Wood Johnson Medical School Clinical Research Center for 24 h. Baseline blood and rectal biopsy samples were obtained before th e volunteers drank 0.6, 1.2, or 1.8 g of green tea solids dissolved in warm water. Blood samples were taken 2, 4, 8, and 24 h after the tea administra tion. Rectal biopsies were obtained at 4, 8, and 24 h. Prostaglandin E-2 (P GE(2)) levels were analyzed by ELISA. Tea polyphenol levels in the blood, u rine, and rectal tissue were measured by high-performance liquid chromatogr aphy using a Coulochem electrode array detection system. Statistical compar isons were made using ANOVA. Decreased levels of PGE(2) in rectal mucosa we re observed at 4 and 8 h after consumption of green tea. There was no corre lation between inhibition of PGE(2) and tissue or plasma levels of tea poly phenols. Ten of 14 subjects demonstrated a response to green tea, as eviden ced by at least a 50% inhibition of PGE(2) levels at 4 h, We conclude that green tea constituents have biological activity in inhibiting PGE(2) synthe sis. Given the 71% "response rate," we believe these data support the study of green tea as a colorectal chemopreventive agent in more long-term Phase II trials.