Diet and esophageal cancer in Calvados (France).

The role of nutrients and food factors in relation to esophageal cancer was observed in a large case-control study in a region having a high incidence of the disease. Several factors that increased or decreased the risk were identified. After adjusting for other covariates, we found that animal proteins and polyunsaturated fats had a significant protective effect. Separating the effects of specific nutrients was difficult because of the intercorrelation between individual intakes of most nutrients. Foods were not so highly intercorrelated. Fresh meat, citrus fruits, and oil were found to be protective. A dietary index combining these foods was used; between the lowest and the highest levels of intake, a nine-fold difference in risk was observed. This effect is added to that of alcohol, which remains the major risk factor. The adequacy of the concepts of nutrients and foods in epidemiological studies is discussed in addition to the theoretical and practical implications of the findings.