Heme iron from meat and risk of colorectal cancer: a meta-analysis and a review of the mechanisms involved

Cancer Prev Res (Phila). 2011 Feb;4(2):177-84. doi: 10.1158/1940-6207.CAPR-10-0113. Epub 2011 Jan 5.

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.

Publication types

  • Meta-Analysis

MeSH terms

  • Animals
  • Colorectal Neoplasms / etiology*
  • Heme / adverse effects*
  • Humans
  • Iron, Dietary / adverse effects*
  • Meat Products / adverse effects*
  • Rats
  • Review Literature as Topic

Substances

  • Iron, Dietary
  • Heme