A large epidemiological study carried out in Japan has concluded that green tea consumption is associated with reduced mortality from all diseases. A prospective cohort of 12,251 elderly people (65-84 years) completed questionnaires including items about frequency of green tea consumption and were followed up for up to six years.

Green tea consumption was found to be associated with a 55% reduction in mortality from all causes. Particularly notable was the protective effect against cardiovascular disease (CVD) - intake of seven cups of green tea per day reduced the chances of dying from heart disease by 75%. Protection against colorectal cancer was also greatly increased, with the most frequent green tea drinkers displaying a 31% reduction in mortality from the disease. (Green tea consumption and mortality among Japanese elderly people: the prospective Shizuoka elderly cohort. Ann Epidemiol. 2009 Oct;19(10):732-9).