Red and processed meat consumption is associated with the risk of
colorectal cancer. Three hypotheses are proposed to explain this association, via
heme-induced oxidation of fat, heterocyclic
amines, or N-
nitroso compounds. Rats have often been used to study these hypotheses, but the lack of enterosalivary cycle of
nitrate in rats casts doubt on the relevance of this animal model to predict nitroso- and
heme-associated human colon
carcinogenesis. The present study was thus designed to clarify whether a
nitrite intake that mimics the enterosalivary cycle can modulate
heme-induced nitrosation and fat peroxidation. This study shows that, in contrast with the starting hypothesis,
drinking water added with
nitrite to mimic the salivary
nitrite content did not change the effect of
hemoglobin on
biochemical markers linked to colon
carcinogenesis, notably lipid peroxidation and cytotoxic activity in the colon of rat. However, ingested
sodium nitrite increased fecal
nitroso-compounds level, but their fecal concentration and their nature (
iron-nitrosyl) would probably not be associated with an increased risk of
cancer. We thus suggest that the rat model could be relevant for study the effect of red meat on colon
carcinogenesis, in spite of the lack of
nitrite in the saliva of rats.