Dose-dependent effect of dietary meat on endogenous colonic N-nitrosation.

TitleDose-dependent effect of dietary meat on endogenous colonic N-nitrosation.
Publication TypeJournal Article
Year of Publication2001
AuthorsHughes, R, Cross, AJ, Pollock, JR, Bingham, S
Date Published2001 Jan
KeywordsAdult, Animals, Cattle, Colon, Cross-Over Studies, Diet, Feces, Humans, Male, Meat, Middle Aged, Nitrites, Nitrogen, Nitroso Compounds, Swine

Human male volunteers were studied in a metabolic facility whilst they were fed randomized controlled diets. In eight volunteers there was a significant increase in faecal apparent total N:-nitroso compounds (ATNC) and nitrite excretion (P < 0.0001 and P = 0.046, respectively) when randomized doses of meat were increased from 0 to 60, 240 and 420 g/day over 10 day periods. Mean (+/- SE) faecal ATNC levels were 54 +/- 7 microg/day when the diets contained no meat, 52 +/- 11 microg/day when the diets contained 60 g meat/day, 159 +/- 33 microg/day with 240 g meat and 199 +/- 36 microg/day with 420 g meat. Higher concentrations of NOC were associated with longer times of transit in the gut (r = 0.55, P = 0.001) and low faecal weight (r = -0.51, P = 0.004). There was no significant decline in levels in individuals fed 420 g meat for 40 days. The exposures found on the higher meat diets were comparable with other sources of N:-nitroso compounds (NOC), such as tobacco smoke. Many NOC are known large bowel initiators and promotors in colon cancer, inducing G-->A transitions in codons 12 and 13 of K-ras. Endogenous NOC formation, combined with prolonged transit times in the gut, may explain the epidemiological associations between high meat/low fibre diets and colorectal cancer risk.

Alternate JournalCarcinogenesis
Citation Key10.1093/carcin/22.1.199
PubMed ID11159760