Asian men are significantly less likely to develop prostate cancer than Western men, and a high level of green tea consumption is likely partly responsible.
A study done at Japan’s Public Health Center monitored 49,920 Asian men, aged 40-69, over a 14-year period (1990-2004). During this time, 404 men developed prostate cancer, 114 of which were advanced cases, 271 were localized cases, and 19 were undetermined.
Advanced prostate cancer is defined in the study as “extraprostatic or metastatic cancer involving lymph nodes or other organs.” Localized prostate cancer is cancer confined solely to the prostate. The study found a correlation between green tea consumption and advanced prostate cancer, but no correlation between green tea consumption and localized prostate cancer.
The study showed that men who drink five or more cups of green tea per day potentially decrease their risk of developing prostate cancer by more than 50%.
The suggested reasons for green tea’s preventative properties against prostate cancer are “antioxidant properties against free radicals, induction of apoptosis, inhibition of cell growth, and the arrest of cell cycle progression.”
There was also a clear designation in the study between green tea and black tea, which are both extracts of the plant “Camellia sinensis.” The main difference is that black tea is fermented, while green tea is not. Black tea was shown in the study to have no direct connection to prostate cancer.
This study does not claim to be conclusive, and does not guarantee that people who drink green tea will reduce their risk for prostate cancer. What the study does provide is a potential explanation of why men in Asia, where there is a high level of green tea consumption, have a much lower rate of advanced prostate cancer than western men.
Source: Defeat Diabetes Foundation: Kurahashi, Norie. Sasazuki, Shizuka. Iwasaki, Motoki. Inoue, Manami. Tsugane, Shoichiro. American Journal of Epidemiology. “Green Tea Consumption and Prostate Cancer Risk in Japanese Men: A Prospective Study.” September 2007.