Colon cancer: dietary modifications required for a balanced protective diet

There is increasing support of the view that our diet is too calorie dense, with its high animal fat, sugar, and alcohol content. Food processing has helped to create this situation as well as the desire to eat sugar- and fat-rich foods. By examining the influence of these dietary effects on colon cancer, experimental animal studies can help dissect the influences not readily assessable by epidemiological means.

The Sprague Dawley rat model of colon cancer induced by dimethylhydrazine provides a means of assessing dietary influences with the use of a semipurified diet and varying a single factor at a time. We have examined the influence of Ca vitamin E, protein type, and cereal dietary fiber sources on tumor burden and incidence in rats on a standardized experimental protocol.

A significant interactive effect has been seen with high Ca and low vitamin E intake in protecting rats from tumors. When comparing differing protein sources, whey protein concentrate was found to be very protective relative to red meat and other protein sources. Spent barley grain was also shown to be very protective relative to wheat bran and commercial barley bran.

There are several potentially useful strategies for protection from colon cancer by varying diet composition. Protein sources such as whey protein concentrate, insoluble dietary fiber from barley grain, and high calcium intake seem to be very promising. These need further detailed examination as to whether they can combine to reduce risk further and to understand better the mechanisms responsible for protection. They may provide greater potential than attempts to lower the fat in the human diet.