Another study, this one out of Japan, talking about the benefits of green tea. The research was done by Japan’s National Cancer Center. The report says that the benefits of drinking 5 cups of green tea a day may be limited to advanced prostate cancer.
Green tea contains between 30 and 40 per cent of polyphenols, while black tea contains between 3 and 10 per cent. Black tea has been fermented which results in the loss of the polyphenols. Oolong tea is semi-fermented tea and the amount of polyphenols is somewhere between the two other types of teas.
The study was commissioned by the Japan Public Health Center-based Prospective Study. It involved 49,920 Japanese men aged from 40 to 69. At the start of the study the men were questioed about their dietary intakes, including how much green tea they drank.
The study, started in 1990, followed until 2004, and 404 men developed cancer. The men who drank five or more cups a day was associated with a 48 per cent reduction in advanced prostate cancer risk, compared to those who only drank less than one cup per day.