S1684 Adherence to a Mediterranean Diet Is Not Associated With Reduced Risk of Development of Microscopic Colitis

Introduction: The pathogenesis of microscopic colitis (MC) has been attributed to an immune response to changes in the gut microenvironment. Diet is the single largest contributor to the gut microenvironment through its influence on microbiome composition/function and epithelial barrier function. Following a Mediterranean diet has been shown to alter gut microbiome composition, reduce inflammatory mediators, and positively impact intestinal epithelial permeability. Nevertheless, the impact of following a Mediterranean diet on risk of MC development has never been studied. In 2 nationwide prospective cohorts we analyzed the association between Mediterranean diet adherence and risk of developing MC. Methods: We performed a prospective cohort study including 169,343 women without a baseline diagnosis of MC in the Nurses’ Health Study (NHS) and NHS II. Through validated semiquantitative food frequency questionnaires ascertained every 4 years beginning in 1990 in NHS and 1991 in NHSII, we derived alternate Mediterranean diet (aMED) scores based on intake of vegetables, fruit, nuts, whole grains, legumes, fish, red/processed meat, alcohol, and monosaturated-to-saturated-fat ratio. Higher scores indicated increased Mediterranean diet adherence. MC diagnoses were confirmed through review of histopathology. Using Cox proportional hazards modeling, we estimated the multivariable-adjusted hazard ratios (aHR) and their respective 95% confidence intervals (CI) for development of MC according to quartiles of aMED score while adjusting for potential confounders. Results: Between 1990 and 2015, we confirmed 213 incident MC cases over 2,959,527 person-years. There was no association between aMED score and risk of developing MC. The aHR of MC was 1.23 (95% CI 0.85-1.78) in the highest quartile of aMED score as compared to the lowest (ptrend = 0.21). The results did not vary based on MC subtype (pheterogeneity = 0.83). We also analyzed the association between the individual aMED components and risk of MC. A positive association was identified between alcohol intake and risk of MC with an aHR of MC of 1.30 (95% CI 1.13-1.49) for each drink of alcohol consumed per day. Conclusion: In 2 large prospective cohorts of US women, there was no association between Mediterranean diet adherence and risk of development of MC. Alcohol intake is associated with MC development. Further studies should address the role of alcohol avoidance in mitigating MC.