In vivo and in vitro effects of fish-containing diets on colon tumour cells in rats.

Polyunsaturated n-3 fatty acids, abundant in sea fish, can inhibit the growth of chemoinduced or transplanted mammary tumours in the rat. Since mammary and colonic cancers have both been linked to a high fat consumption, we studied the effect of 2 diets moderately (7% fish meal) or strongly (9% fish oil) enriched in fish fatty acids on the growth of colon cancer cells subcutaneously inoculated into syngeneic rats. The diets had no effect on the in vivo tumor growth and on the in vitro tumouricidal activity of peritoneal macrophages or splenic lymphocytes.