Sixty men with high-grade prostate intraepithelial neoplasia (the main pre-malignant lesion that leads to prostate cancer) were randomly assigned to receive, in double-blind fashion, 600 mg/day of green tea catechins (a type of polyphenols) or placebo for one year. After one year, prostate cancer had developed in 3.3% of the patients in the active-treatment group and in 30% of those in the placebo group (p < 0.01).

Comment: These results suggest that supplementing with green tea polyphenols can prevent the progression of high-grade prostate intraepithelial neoplasia to prostate cancer. The results of this study and of the study cited above are consistent with are large body of animal research and in vitro data that demonstrated an anticancer effect of green tea. While green tea and black tea are both derived from the same plant leaves (Camellia sinensis), the former contains a higher concentration of the polyphenols that are believed to inhibit cancer development. Other research suggests that green tea consumption can help prevent cardiovascular disease and dental caries.

Bettuzzi S, et al. Chemoprevention of human prostate cancer by oral administration of green tea catechins in volunteers with high-grade prostate intraepithelial neoplasia: a preliminary report from a one-year proof-of-principle study. Cancer Res. 2006;66:1234-1240.