Are Catechins, Polyphenols in Tea, Good for Your Health?

Tea together with coffee is the most consumed beverage in the world and contains large amounts of catechins, one kind of polyphenols. Experiments in vitro have shown that catechins have various beneficial activities such as chemopreventive one for cardiovascular disease and cancer. Catechins also exhibit cytotoxic effects by damaging the membrane of cells and/or the production of hydrogen peroxide (H2O2). The development of preventive methods for the production of H2O2 in green tea was summarized. Effects of green tea on human health are contradictory in epidemiological studies, possibly due to the difficulty in their uptake into the body and their cytotoxicity. Beverages without sugar are recommended for water intake and mental relaxation, since no noxious side effects of such beverages have been reported in the epidemiological research up to now.