Diet and Gut Microbiota in Inflammatory Bowel Disease: A Clinical and Nutritional Perspective

Inflammatory bowel diseases, comprising Crohn’s disease and ulcerative colitis, represent chronic inflammatory disorders with rising global incidence, underscoring the pivotal role of modifiable environmental factors in disease pathogenesis. Diet and intestinal microbiota have emerged as critical bidirectional therapeutic targets through complex interactions with host immune responses. Epidemiological evidence demonstrates that healthy and high fiber diets reduce disease risk, while ultra-processed foods and inflammatory dietary patterns increase susceptibility. Therapeutic nutritional interventions, including exclusive enteral nutrition, the Crohn’s Disease Exclusion Diet combined with partial enteral nutrition, and the Mediterranean diet can induce and maintain clinical remission while promoting favorable microbiome modifications characterized by the enrichment of butyrate-producing taxa such as Faecalibacterium prausnitzii and Roseburia species, alongside a reduction in pathogenic Proteobacteria. Micronutrient deficiencies affect up to 78% of patients through malabsorption, chronic blood losses, dietary restrictions, and drug–nutrient interactions. Nutritional status significantly impacts surgical outcomes, with preoperative malnutrition and sarcopenia associated with increased postoperative complications, and it reciprocally influences biologic therapy response. Integration of personalized, microbiome-informed dietary strategies as complementary components of comprehensive treatment plans represents a promising therapeutic frontier, requiring multidisciplinary collaboration, rigorous clinical trials with standardized microbiome analyses, and precision nutrition algorithms accounting for disease phenotype, baseline microbial composition, and individual patient characteristics to optimize outcomes and improve quality of life.