New findings add to mounting evidence suggesting that tea consumption may lower the risk of developing prostate cancer (PCa).

The findings are based on a population-based case-control study conducted in King County, Washington. The study, by Milan S. Geybels, MSc, of the Department of Epidemiology, Maastricht University, Maastricht, The Netherlands, and colleagues examined associations between PCa risk and tea and coffee consumption. The tea-related analysis focused on 863 PCa cases and 863 controls; the coffee-related analysis included 894 cases and 860 controls.

In adjusted analyses, men who consumed two or more cups of tea per day had a significant 37% decreased risk of PCa compared with men who consumed one cup of tea or less per week, investigators reported online ahead of print in Cancer Causes and Control. Geybels’ group found no association between coffee consumption and PCa risk.

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The authors explained that tea and coffee contain biologically active compounds that may have anti-cancer effects. The biological properties of tea are mostly attributable to its polyphenol content, whereas coffee is a complex mixture of many potentially chemopreventive compounds, they pointed out.

The potential anticancer activities of polyphenols, the researchers explained, may be related to their antioxidant activities, anti-inflammatory effects, effects on enzyme activities, and inhibition of angiogenesis.

Animal studies and research involving cell lines have shown that extracts of green and black tea decrease PCa growth, they noted. Most of these studies have used polyphenolic fractions isolated from green tea or purified epigallocatechin-3-gallate, a catechin found almost exclusively in tea, the investigators observed.

Geybels and her colleagues cited a previous study published in Cancer Research (2006;66:1234-1240) in which 60 men with high-grade prostate intraepithelial neoplasia—which is thought to be a precursor to PCa—were assigned to receive either three 200 mg green tea catechins capsules per day or placebo. After one year, only one tumor was detected among the 30 men in the treatment group, whereas nine tumors were found among the 30 placebo recipients.