Diet and carcinogenesis: historical perspectives

Some 40-50 years ago, experiments with animals began to provide conclusive evidence that diet can significantly influence carcinogenesis. Underfeeding or severe restriction of caloric intake to between one-half and two-thirds of normal had a general inhibitory effect on development of tumors of various types. On the other hand, high fat diets were found to enhance tumor yields relative to low fat diets. The effect of dietary fat was shown to be independent of caloric intake and was more selective for certain types of tumors. Both dietary fat and caloric restriction appear to exert their effects mainly at the promotional stage of carcinogenesis, although the exact mechanisms are not known. Interest in the role of diet in carcinogenesis has been revived in recent years by epidemiologic data that show correlations between certain dietary constituents, such as dietary fat, and cancer incidence at particular sites in the body and mortality. These epidemiologic observations have, in turn, led to an increase in research on effects of diet on carcinogenesis in animal models.