Unraveling the mystery of green tea and cancer

Abstract

Green tea has recently been the topic of much attention in the health and scientific communities. Anecdotal evidence pointing to the health benefits of green tea directed researchers to investigate this beverage's pharmacological activities. Epidemiological studies, although somewhat inconclusive, suggested that consumption of green tea had health-promoting effects, particularly in the prevention of cancer. Studies with laboratory animal studies further supported this observation by providing evidence that the administration of green tea extract reduced the occurrence and progression of chemical-induced carcinogenesis. The polyphenolic components of green tea were identified as the anticarcinogenic agents. In vitro studies with human cells in culture, conducted to understand the molecular and cellular bases for the chemopreventive potencies of green tea, showed that green tea polyphenols exhibited greater cytotoxicity to cancer cells than to normal cells. In the Laboratory of In Vitro Toxicology at Stem College for Women, I evaluated the cytotoxicity of catechin gallate (CG), a little-studied polyphenol present in green tea. Polyphenols are known act both as both antioxidants and prooxidants, in addition to displaying other modes of activity. My studies showed that in cell culture medium, CG acted as a prooxidant, generating hydrogen peroxide, and was preferentially cytotoxic to cancer, than to normal, cells isolated from the human oral cavity. Although in vitro studies, in general, have elucidated some of the mechanisms by which the polyphenolic constituents of green tea protect against cancer, the healthpromoting properties of this popular beverage still remain somewhat of a mystery. More research is necessary to understand the role of green tea in cancer prevention.