COLORECTAL-CANCER - CONTROVERSIAL ROLE OF MEAT CONSUMPTION

Diet is supposed to influence the colorectal cancer etiology,, but the precise causative factors, are yet unknown. international ecological studies show a strong correlation between meat consumption and the col orectal cancer incidence. Most case-control studies (22 of 29) show an increased risk to develop a colorectal cancer for those eating higher amounts of meat. In contrast only 2 out of the 5 best prospective coh ort studies have shown this positive association for red meat Two stud ies out of 4 show an association with processed meat. Consumption of w hite meat or of fish is not associated with a high risk, and might eve n reduce the occurrence of colorectal cancer Several plausible hypothe ses concerning the link between meat and colon carcinogenesis have bee n suggested They involve saturated fat, protein, iron, heterocyclic am ines produced by cooking, and N-nitroso compounds. High fat diets may promote cancer because they have a high caloric content or because the y lend to increased levels of bile acids in the colonic lumen. Six exp erimental studies are published on the effect of meat, or meat fractio ns, on the colon tumor incidence in rodents initiated with chemical ca rcinogens. Data from these studies do not support the belief that red meat (beef) has a specific effect on intestinal carcinogenesis. Instea d diets containing beef meat (rooked or raw) decrease carcinogenesis w hen compared to control diets containing similar amounts of fat and pr otein of vegetal origin. However, high fat or high protein diets often increase carcinogenesis when compared to low fat or low protein diets . Thus, one cannot state, nor exclude, that meat promotes colorectal c ancer.