A Very Low Dose of Green Tea Polyphenols in Drinking Water Prevents N‐Methyl‐N‐nitrosourea‐induced Colon Carcinogenesis in F344 Rats

The effect of tea polyphenols, major constituents of tea, on colon carcinogenesis was investigated. A total of 129 female F344 rats were given an intrarectal instillation of 2 mg of N‐methyl‐N‐nitrosourea 3 times a week for 2 weeks, and received a water solution of green tea extract (GTE) as drinking water throughout the experiment. Autopsies at week 35 revealed significantly lower incidence of colon carcinomas in rats ingesting 0.05%, 0.01% or 0.002% GTE solution than in controls ingesting 0% GTE solution: 43%, 40% and 33% vs. 67%. The data suggest that GTE, even at a very low dose (0.002% solution), has a potent inhibitory effect on colon carcinogenesis.