A new study from Japan, published in the Journal of Epidemiology, shows that drinking five cups of green tea daily can cut your chances of developing prostate cancer by nearly 50%.
Researchers from Japan's National Cancer Center were quick to point out that the benefits of green tea may be limited to prevention of advanced prostate cancer; the team saw no effects on localized cancer in patients who already had the disease.
Of course, this news simply adds to a growing list of benefits that links tea and tea extracts to a great variety of benefits, ranging from lowered risk of cancers and obesity, to protection against Alzheimer's. All of these benefits seem to be linked to the polyphenol content of the tea.
Green tea contains between 30 and 40 per cent of water-extractable polyphenols, while black tea (which starts as green tea and is then changed via fermentation) contains between 3 and 10 per cent. Just as red wine seems to be the most powerful in the wine world, the green teas show a considerable head-and-shoulders improvement in health benefits over their fermented cousins.
The four primary polyphenols found in fresh tea are epigallocatechin gallate (EGCG), epigallocatechin, epicatechin gallate, and epicatechin. EGCG is now seen in a variety of products in the dietary supplement marketplace.
This study, known as the "Japan Public Health Center-based Prospective Study" reviewed 49,920 Japanese men aged at their prime for prostate cancer (from 40 to 69). Each participant completed a questionnaire at the start of the study to identify dietary intake, including habitual green tea consumption. The men were followed from 1990 through 2004, and 404 cases of prostate cancer were diagnosed in this time. Of these cases, 114 were advanced cases, 271 were localized, and 19 were undetermined.
Increased intake of green tea was shown to be linked to reduced risk. Drinking five or more cups a day was associated with a 48 per cent reduction in advanced prostate cancer risk, compared to drinking less than one cup per day.
Over half a million new cases of prostate cancer are diagnosed every year worldwide, and the cancer is the direct cause of over 200,000 deaths. The incidence of the disease is increasing with a rise of 1.7 per cent over the last 15 years. In short, this disease is becoming more and more of a worry for health officials and the public all over the world.