Tea and cancer: a review of the epidemiological evidence.

Numerous recent reports of inhibition of carcinogenesis in experimental animals by tea or tea compounds raise the possibility that tea drinking may lower cancer risk in humans. Thus, studies around the world were reviewed to evaluate whether there is a consensus of epidemiologic evidence on the relation of tea drinking to cancer overall or to specific cancers. Ecological data suggest at most a modest benefit, since there is considerable international variation in tea consumption but generally small differences in cancer rates. More relevant case-control and cohort studies show mixed results. Detailed data from these studies on cancer risks according to amount and duration of tea intake are quite limited, and consistent dose-related patterns. have yet to emerge. Nevertheless, several investigations point to the possibility of lowered risks of digestive tract cancers among tea drinkers, especially those consuming green tea. Further research, particularly in population with wide ranges of tea consumption, is needed before definitive conclusions on tea's impact upon cancer risk can be reached.