Prevention of coronary heart disease and cancer by tea, a review.

Biomedical research has uncovered the mechanisms whereby tea promotes good health and lowers the risk of major chronic diseases, such as heart disease and many types of cancer. The active components in tea are polyphenols, epigallocatechin gallate in green tea, theaflavins and thearubigins in black tea. Green and black tea and the polyphenols have similar beneficial effects. The mechanisms are categorized into 5 groups. 1) Tea polyphenols are powerful antioxidants. They decrease the oxidation of LDL cholesterol and lower the risk of heart disease, and also inhibit action of reactive oxygen species mediating the oxidation of DNA associated with carcinogenesis 2) Tea polyphenols induce detoxifying enzymes, glucuronosyl transferases, eliminating active forms of carcinogens and other toxicants, accounting for the lower cancer risk. 3) Tea polyphenols lower duplication rates of cancer cells and inhibit the growth of cancer, increase apoptosis and lower angiogenesis. 4) Tea polyphenols alter the intestinal bacterial flora, suppressing undesirable bacteria and favoring growth of beneficial bacteria. 5) Aging phenomena, and diseases associated with the formation of reactive oxygen species (ROS) are inhibited.