In order to examine the risks of cancer of the upper aerodigestive tract (UADC) associated with nutrient intake, a case-control study was conducted in Uruguay in the period of January 1996-December 1997. All patients afflicted with cancer of the oral cavity, pharynx, larynx, and esophagus, were included in the study. Cases were frequency-matched with hospitalized patients on age, sex, residence, and urban/rural status. A strong positive association with protein intake was observed (OR 2.5, 95% CI 1.5-4.4), whereas antioxidants were associated with an inverse association (OR for vitamin C 0.5, 95% CI 0.3-0.8). Non-nutritive substances, like flavonoids displayed a marked reduction in risk of 70%. Possible mechanisms for these findings are discussed.