Haem, not protein or inorganic iron, is responsible for endogenous intestinal N-nitrosation arising from red meat

Cancer Res. 2003 May 15;63(10):2358-60.


Many N-nitroso compounds (NOC) are carcinogens. In this controlled study of 21 healthy male volunteers, levels of NOC on a high (420 grams) red meat diet were significantly greater (P = 0.001) than on a low (60 grams) meat diet but not significantly greater when an equivalent amount of vegetable protein was fed. An 8-mg supplement of haem iron also increased fecal NOC (P = 0.006) compared with the low meat diet, but 35-mg ferrous iron had no effect. Endogenous N-nitrosation, arising from ingestion of haem but not inorganic iron or protein, may account for the increased risk associated with red meat consumption in colorectal cancer.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial

MeSH terms

  • Adult
  • Aged
  • Animals
  • Cattle
  • Cross-Over Studies
  • Dietary Supplements
  • Feces / chemistry
  • Heme / pharmacology*
  • Humans
  • Intestine, Large / drug effects
  • Intestine, Large / metabolism*
  • Iron, Dietary / pharmacology*
  • Male
  • Meat / adverse effects*
  • Middle Aged
  • Nitrites / metabolism
  • Nitroso Compounds / metabolism*


  • Iron, Dietary
  • Nitrites
  • Nitroso Compounds
  • Heme