Nutrition and Health: Nutritional and Health-Promoting Properties of Dairy Products: Colon Cancer Prevention

Some epidemiological studies have identified fermented and nonfermented dairy foods as providing significant protection against colon cancer. Though the interpretation of such data is complicated by the presence of many confounding factors, the effect of milk intake on distal colon cancer has been consistent. Though calcium, which in most diets is largely derived from milk and which is present in milk in a highly bioavailable form, has usually been considered the milk constituent most likely to confer this benefit, recent data point to the effect of milk and milk products independent of calcium.Even though no data from intervention studies are available for milk and milk products per se, two intervention studies in adenoma-prone populations in Europe and the United States have shown that calcium supplements in excess of 1g day^-1 produced a significant, though modest, reduction in adenomatous polyp recurrence rates.Other components of dairy foods that have been shown to reduce mutagenicity or genotoxicity or diminish colon tumor formation in animal models of the disease include whey proteins, vitamin D, conjugated linoleic acid, sphingolipids, lactulose, and butyrate. It is not possible currently to prioritize these components in terms of their potential contribution, to evaluate adequately their effects in combination, or to confirm their relevance in humans, but the fact that they occur together in dairy foods is supportive of their potential value as part of a cancer-preventing diet.A number of possible mechanisms could be operating in cancer prevention, and this is a very productive area for ongoing research. It should in time help to confirm desirable dietary strategies, as well as to predict any modifications to dairy foods that are likely to be of additional benefit in this respect.