Mechanisms of pro-cancer effect of meat consumption: a review

Recent meta-analyses of epidemiological studies show that high consumers of red meat, either fresh or processed, are at increased risk of colorectal cancer. The risk increase is significant but modest (+25%) and the French national cancer institute recommends since 2009 to eat less than 500g red meat per week and to limit as much as possible the intake of high-fat or salty deli meats. Also, experimental studies have proved that beef meat and cured pork meat promote colon carcinogenesis in rats. Some compounds present in meat such as heme iron, the curing-agent nitrite, heat-induced mutagens (heterocyclic aromatic amines) or fat in excess could be considered as colorectal cancer promoters. Heme iron amplifies not only lipid peroxidation and cytotoxic alkenal production, but also formation of carcinogenic N-nitroso-compounds, in synergy with nitrites from cured meat. The carcinogenic effect of heterocyclic aromatic amines is mostly seen in specific genotypes with a high metabolic capacity. Finally, fatty meat may non-specifically promote cancer due to caloric excess.