Tea polyphenols in preventing cardiovascular diseases.

Epidemiological observations suggesting an inverse correlation between tea consumption and the incidence of cardiovascular diseases have been well established [1–4]. The review by Stangl et al. gives an overview of the effects of polyphenolic compounds in tea on the function of the cardiovascular system, especially on various signal transduction pathways in cardiovascular cells [5]. The underlying mechanisms of tea polyphenols in preventing cardiovascular disease, however, are yet to be well understood. It is widely known, but still open to question, why the incidence of coronary events (death definitely or probably due to coronary heart disease or non-fatal myocardial infarction) in Japanese is substantially lower than in Western populations [6]. In Japan, as well as in other Asian countries, tea consumption is very high, and green tea, in particular, is favored by Japanese. Green tea is made by steaming, not fermenting, freshly harvested tea leaves and therefore contains more antioxidants and vitamins than fermented teas such as oolong or black tea. The major polyphenols of green tea are catechins, which constitute about one third of green tea's total dry weight. The major catechin is (−)-epigallocatechin-3-gallate (EGCG). The biological effects of tea polyphenols are mainly focused on the effects of EGCG, including the prevention of LDL oxidation, reduction of platelet aggregation, lipid regulation, and inhibition of proliferation andmigration of smoothmuscle cells [7].Anyof these factors might be promising in reducing cardiovascular diseases. Recently, in Japan, a large population-based cohort study of 40,530 subjects showed green tea consumption to be inversely associatedwithmortality due to cardiovascular disease [8]. In another study that enrolled 203 patients who underwent coronary angiography, the observation that green tea consump-