The effect of haem in red and processed meat on the endogenous formation of N-nitroso compounds in the upper gastrointestinal tract.

TitleThe effect of haem in red and processed meat on the endogenous formation of N-nitroso compounds in the upper gastrointestinal tract.
Publication TypeJournal Article
Year of Publication2007
AuthorsLunn, JC, Kuhnle, G, Mai, V, Frankenfeld, C, Shuker, DEG, Glen, RC, Goodman, JM, Pollock, JRA, Bingham, SA
JournalCarcinogenesis
Volume28
Issue3
Pagination685-90
Date Published2007 Mar
ISSN0143-3334
KeywordsAnimals, Ascorbic Acid, Gastric Mucosa, Heme, Humans, Ileostomy, Ileum, Kinetics, Meat, Meat Products, Nitroso Compounds, Vitamin E
Abstract

Red and processed meat (PM) consumption increases the risk of large bowel cancer and it has been demonstrated that haem in red meat (RM) stimulates the endogenous production of N-nitroso compounds (NOCs) within the human intestine. To investigate whether N-nitrosation occurs in the upper gastrointestinal tract, 27 ileostomists were fed diets containing no meat, or 240 g RM or 240 g PM in a randomly assigned crossover intervention design carried out in a volunteer suite. Endogenous NOC were assessed as apparent total N-nitroso compounds (ATNC) in the ileostomy output. ATNC concentration in the diets was 22 microg ATNC/kg (RM) and 37 microg ATNC/kg (PM), and 9 microg ATNC/kg in the no meat diet. Levels significantly increased to 1175 microg ATNC/kg SEM = 226 microg ATNC/kg) following the RM (P=0.001) and 1832 microg ATNC/kg (SEM=294 microg ATNC/kg) following PM (P<0.001) compared to the no meat diet (283 microg ATNC/kg, SEM=74 microg ATNC/kg). ATNC concentrations in the ileal output were equivalent to those measured in faeces in similarly designed feeding studies. Supplementation with either 1 g ascorbic acid or 400 IU alpha-tocopherol had no effect on the concentration of ATNC detected in the ileal output. In in vitro experiments, N-nitrosomorpholine (NMor) was formed in the presence of nitrosated haemoglobin, at pH 6.8 but not in the absence of nitrosated haemoglobin. These findings demonstrate that haem may facilitate the formation of NOC in the absence of colonic flora in the upper human gastrointestinal tract.

DOI10.1093/carcin/bgl192
Alternate JournalCarcinogenesis
Citation Key10.1093/carcin/bgl192
PubMed ID17052997
Grant ListMC_U105630924 / / Medical Research Council / United Kingdom