Two-sample Mendelian randomization analysis evaluates causal associations between dietary habits and rectal polyps

Introduction: rectal polyps are a common precancerous condition, and dietary habits are hypothesized to influence their development. Objective: this study aims to investigate the causal association between genetically predicted dietary habits and the risk of rectal polyps. Methods: we utilized summary data from genome-wide association studies (GWAS) on dietary habits and rectal polyps in individuals of European ancestry, sourced from the latest International Epidemiology (IEU) dataset. A two-sample Mendelian Randomization (MR) approach was employed using the Inverse Variance Weighted (IVW) method, alongside weighted median, weighted mode, and MR-Egger regression methods. Sensitivity analyses were conducted, including MR-Egger, MR-PRESSO, Cochran's Q, and leave-one-out analyses, to assess the robustness of the findings. Results: the IVW method revealed a significant association between processed meat intake and the risk of rectal polyps (IVW: OR = 0.9945, 95 % CI: 0.9892-0.9999, p = 0.045). However, no significant causal associations were observed between the remaining dietary habits and the risk of rectal polyps Sensitivity analyses revealed heterogeneity in the alcohol-rectal polyp association, but no pleiotropy or outliers. Beef intake-rectal polyp association showed a potential pleiotropy signal, but no outliers. Leave one out analysis confirmed robust results. Conclusions: the MR study suggests a potential causal effect of processed meat intake on the risk of rectal polyps, highlighting the importance of dietary factors in the development of this condition. The findings underscore the need for further research to elucidate the biological mechanisms and to confirm these preliminary results.