The effects of partial replacement of red and processed meat with legumes on the concentration of fecal N-nitroso compounds in healthy Finnish men – 6-week randomized clinical trial

Background: Endogenous formation of possibly carcinogenic N-nitroso compounds may partly explain the association between red and processed meat and colorectal cancer. The aim of this study was to examine the effects of partial replacement of red and processed meat with legumes on the fecal total and heme-originated N-nitroso compounds (NOC) in healthy working-aged Finnish men.
Methods: The study was a 6-wk parallel design randomized clinical trial with two groups following either a diet supplemented with red and processed meat or a diet supplemented with legumes and red and processed meat. Total and heme-originated NOCs were analyzed from fecal homogenates using Ecomedics CLD 88. Statistical analyses were conducted using IBM SPSS Statistics 27. Independent samples t-test and Chi-Square test were used to assess the differences between the intervention groups at the baseline. Differences in total and heme-originated NOCs between the intervention groups at the endpoint were analyzed using ANCOVA (adjusted for baseline values). For correlations, Pearson correlation was used.
Results: 102 men completed the study. No significant differences between the groups were reported at the baseline. At the endpoint, fecal concentrations of total NOC (p < 0.0001) and heme-originated NOC (p < 0.0001) were lower in the legume and red meat group than in the red meat group. A moderate negative correlation between stool volume and NOC concentrations was observed.
Conclusions: The results indicate that even a partial replacement of red and processed meat with legume products can significantly reduce the total and heme-originated NOC concentrations in feces and potentially reduce the risk for the development of CRC.