Mediation role of body mass index in the relationship between food-specific serum immunoglobulin G reactivity and colorectal adenomas in a Chinese population: a cross-sectional study

Background: Colorectal adenomas (CAs) represent a significant global health issue, particularly in China, where lifestyle modifications have contributed to their increased prevalence. These adenomas are precursors to colorectal cancer. While high-fiber diets have been shown to decrease risk, the implications of food-specific serum immunoglobulin G reactivity (FSsIgGR) on CAs remain uncertain and warrant further investigation. Objectives: To investigate the association between FSsIgGR and the occurrence of CAs in the Chinese population, assess the mediating influence of body mass index (BMI), and offer insights into potential prevention strategies. Design: A retrospective cross-sectional study. Methods: This study is based on 8796 individuals who underwent colonoscopy at the Second Medical Center of Chinese PLA General Hospital from 2017 to 2021. We examined the relationship between FSsIgGR and CAs using logistic regression, controlling for various confounders. Interaction effects were explored through subgroup analysis. We addressed missing data using multiple imputation and confirmed the robustness of our findings through sensitivity analysis. The role of BMI as a mediator was quantified using structural equation modeling. Results: The cohort comprised 2703 patients diagnosed with CAs and 6093 polyp-free controls, with an average age of 50.1 years, of whom 70.1% were male. The analysis revealed a significant inverse association between FSsIgGR and the incidence of CAs (adjusted odds ratio = 0.97; 95% confidence interval: 0.95–0.99; p