Inhibition of dietary fat-promoted colon carcinogenesis in rats by supplemental calcium or vitamin D3.

A 2 X 2 X 2 factorial experimental design was used to investigate the effects of supplemental calcium (Ca) (0.5% versus 1.0% of diet as Ca gluconate) and vitamin D3 (D) (1000 IU/kg diet versus 2000 IU/kg diet) on 1,2-dimethylhydrazine-induced colon carcinogenesis in male F344 rats promoted with a 20% corn oil diet. Animals on the high-fat (HF) diet had an increased tumor incidence compared to the low-fat (LF) control diet (86% versus 53%, P less than 0.05) and supplemental Ca or D reduced this to or below the LF incidence (HF + Ca: 53%, HF + D: 47%). However, supplemental Ca or D had no inhibitory effect with LF diets (LF + Ca: 67%, LF + D: 60%). The results of this study indicate a possible role for supplemental Ca or D in the prevention of colon cancer, effective only in HF diets.