title: Heme iron from meat and risk of colorectal cancer: a meta-analysis and a review of the mechanisms involved.
abstract: Red meat and processed meat intake is associated with a risk of colorectal cancer, a major cause of death in affluent countries. Epidemiological and experimental evidence supports the hypothesis that heme iron present in meat promotes colorectal cancer. This meta-analysis of prospective cohort studies of colon cancer reporting heme intake included 566,607 individuals and 4,734 cases of colon cancer. The relative risk of colon cancer was 1.18 (95% CI: 1.06-1.32) for subjects in the highest category of heme iron intake compared with those in the lowest category. Epidemiological data thus show a suggestive association between dietary heme and risk of colon cancer. The analysis of experimental studies in rats with chemically-induced colon cancer showed that dietary hemoglobin and red meat consistently promote aberrant crypt foci, a putative precancer lesion. The mechanism is not known, but heme iron has a catalytic effect on (i) the endogenous formation of carcinogenic N-nitroso compounds and (ii) the formation of cytotoxic and genotoxic aldehydes by lipoperoxidation. A review of evidence supporting these hypotheses suggests that both pathways are involved in heme iron toxicity.
authors.affiliation: INRA TOXALIM (Research Centre in Food Toxicology), Université de Toulouse; INP ENVT, Toulouse, France.
authors.forename: Nadia M
authors.initials: NM
authors.lastname: Bastide
authors.forename: Fabrice H F
authors.initials: FH
authors.lastname: Pierre
authors.forename: Denis E
authors.initials: DE
authors.lastname: Corpet
mesh_terms: D000818:Animals; D015179:Colorectal Neoplasms / Q000209:etiology*; D006418:Heme / Q000009:adverse effects*; D006801:Humans; D019266:Iron, Dietary / Q000009:adverse effects*; D008461:Meat Products / Q000009:adverse effects*; D051381:Rats; D012196:Review Literature as Topic
chemical_list: D019266:Iron, Dietary; D006418:Heme