Colorectal cancer and the consumption of foods: a case-control study in Belgium.

A case-control study on 453 cases with colon cancer, 365 with rectal cancer, and 2,851 population controls was carried out in two Belgian provinces known to differ in certain dietary habits, particularly with regard to the use of butter. All raw vegetables had a clear protective effect for both colon and rectal cancer; bread was also protective for colon cancer. Starchy foods and foods rich in oligosaccharides (sugar) caused an increased risk for both colon and rectal cancer. No other foods were found to have a systematic effect in both sexes and in both provinces, either in one direction or in the other, except for maize, soybean, and sunflower oils, which were clearly protective in all cases. Among the foods contributing to the intake of fats, there was no effect either for butter, margarine, or fatty meats; the only clear-cut protective effect was that of the oils having a high polyunsaturated-to-saturated ratio. These findings are consistent with our previous findings on the role nutrients play in the relationship with colon and rectal cancers.