Ultra-Processed Foods and Inflammatory Bowel Disease: A Narrative Review of Epidemiology, Mechanisms, and Dietary Implications.

Ultra-processed foods (UPFs), industrial formulations rich in refined substrates and additives, have been increasingly examined as plausible contributors to gut dysbiosis and mucosal inflammation relevant to inflammatory bowel disease (IBD). This narrative review synthesizes epidemiological, mechanistic, and interventional evidence on UPF intake and IBD based on a structured literature search from 2010 to 2025. Large-scale prospective cohorts consistently associate higher UPF intake with increased risk of Crohn's disease (CD), whereas findings for ulcerative colitis (UC) remain weaker or inconsistent. Among individuals with established IBD, observational data suggest that greater UPF consumption correlates with higher disease activity and relapse, although potential confounding and reverse causation must be considered. Preclinical studies demonstrate that specific UPF constituents-including emulsifiers, carrageenan, maltodextrin, microparticles, and excess dietary salt-can disrupt epithelial barrier integrity, alter the gut microbiota, and activate immune pathways, providing biological plausibility while underscoring translational gaps. Interventional evidence, particularly for exclusive enteral nutrition and the Crohn's Disease Exclusion Diet, suggests clinical benefit from reducing UPFs or selected additives, mainly in CD, though data in adults and UC remain limited. Overall, current evidence indicates that dietary strategies to limit UPF exposure may represent a promising and modifiable component of IBD management. Future research should prioritize standardized exposure assessment, mechanism-based human trials, and personalized nutrition approaches to refine clinical applicability.