Environmental risk factors of inflammatory bowel disease: toward a strategy of preventative health

The pathogenesis of inflammatory bowel disease (IBD) involves a complex interplay between genetic, environmental, and microbial factors. Many of these environmental determinants are modifiable, offering opportunities to prevent disease or delay its onset. Advances in the study of preclinical IBD cohorts offer the potential to identify biomarkers that predict individuals at high risk of developing IBD, enabling targeted environmental interventions aimed at reducing IBD incidence. This review summarizes findings from 79 meta-analyses on modifiable environmental factors associated with the development of IBD. Identified risk factors include smoking, Western diets, ultra-processed foods, and early life antibiotic use, while protective factors include breastfeeding, Mediterranean diets rich in fiber, plant-based foods, and fish, along with an active physical lifestyle. Despite the promise shown by observational data, interventional or randomized controlled studies evaluating the efficacy of modifying environmental risk factors remain limited and mostly focus on dietary intervention. This review aims to inform the design of higher quality interventional and randomized controlled studies for disease prevention while providing actionable guidance to healthcare providers on reducing the risk of developing IBD through environmental modifications.