Diet and nutrition in the etiology of oral cancer.

Epidemiological studies worldwide have implicated dietary and nutritional factors in the development of oral and pharyngeal cancer. Dietary information in these case-control studies generally was collected through food-frequency questionnaires. Consistently, these studies observed a protective effect of a diet high in fruit intake, reflected in a 20-80% reduction in oral cancer risk. A high intake of foods considered to be dietary staples in particular cultural groups, possibly indicating a generally impoverished diet, has been linked to excess risk. Indigenous dietary practices that in single studies were found to increase risk include a high intake of chili powder and wood stove cooking. Supplementation with various vitamins has been protective in a few studies. Chemoprevention trials generally have found that chemopreventive agents reduce the size of oral leukoplakia lesions or the frequency of second primary oral cancers. The most consistent dietary findings across multiple cultural settings are a protective effect of high fruit consumption and the carcinogenic effect of high alcohol intake.