Coffee and tea consumption in relation to the risk of large bowel cancer: a review of epidemiologic studies.

Most of the few epidemiologic investigations of the relation of methylxanthine ingestion to risk of large bowel cancer have concerned coffee consumption. A slightly increased risk in coffee drinkers was suggested by one study, no association by another and an inverse association by four, but there was a statistically significant trend across levels of consumption in only one of the latter studies. Based on the data on hand, there is little reason for concern that coffee consumption increases the risk. Although some evidence suggests an inverse association, the data are not compelling and a biologic mechanism is not established. There is even less information on tea consumption and the relation of consumption of this beverage to risk of large bowel cancer is unknown.