Dietary Nitrosamines from Processed Meat Intake as Drivers of the Fecal Excretion of Nitrosocompounds

Diet is one of the main exogenous sources of potentially carcinogenic nitrosamines (NAs) along with tobacco and cosmetics. Several factors can affect endogenous N-nitroso compounds (NOCs) formation and therefore the potential damage of the intestinal mucosa at initial colorectal cancer stages. To address this issue, 49 volunteers were recruited and classified according to histopathological analyses. Lifestyle and dietary information were registered after colonoscopy. The mutagenicity of fecal supernatants was assayed by a modified Ames test. Fecal heme-derived NOCs and total NOC concentrations were determined by selective denitrosation and chemiluminescence-based detection. Results revealed processed meats as the main source of dietary nitrites and NAs, identifying some of them as predictors of the fecal concentration of heme-derived and total NOCs. Furthermore, increased fecal NOC concentrations were found as the severity of colonic mucosal damage increased from the control to the adenocarcinoma group, these concentrations being strongly correlated with the intake of the NAs N-nitrosodimethylamine, N-nitrosopiperidine, and N-nitrosopyrrolidine. Higher fecal NOC concentrations were also noted in higher fecal mutagenicity samples. These results could contribute to a better understanding of the importance of modulating dietary derived xenobiotics as related with their impact on the intestinal environment and colonic mucosa damage.