Modulating effects of calcium in animal models of colon carcinogenesis and short-term studies in subjects at increased risk for colon cancer.

A substantive amount of evidence from animal models supports the hypothesis that dietary fat is an etiological factor in colon cancer. Although various theories account for possible mechanisms, it is clear that under the influence of a basic colonic pH, fatty acids and bile acids may become highly surfactant in the colon, causing cell loss and compensatory hyperproliferation. Calcium likely reduces lipid damage in the colon by complexing with fat to form mineral-fat complexes or soaps. It has been shown in an increasing number of animal experiments that calcium has the ability to inhibit colon cancer. In limited studies in man, the colonic hyperproliferation associated with increased risk for colon cancer has been reversed for short periods by administration of supplemental dietary calcium. Taken together the available evidence suggests that increases in the daily intake of calcium in the diet may provide a means of colorectal-cancer control.