EFFECT OF A FISH-CONTAINING DIET ON CHEMICALLY-INDUCED COLON CARCINOGENESIS IN RATS

Addition to the diet of high levels of fish oil or n-3 polyunsaturated fatty acids has been reported to decrease the incidence of chemically-induced colon tumors in rats. In the present work, the effect of partially substituting fish meal for meat meal in a standard rat diet was studied on intestinal carcinogenesis induced by 1,2-dimethylhydrazine. The fish-containing diet significantly enhanced the number and size of the colonic tumors. These tumors tended to be more distally located, less differentiated, and more invasive than the corresponding tumors in the group fed the diet without fish. These results suggest that substituting fish for meat in a standard diet does not protect rats against chemically-induced colon carcinoma, but may rather enhance the number and invasiveness of colonic tumors.