Nutritional composition of diets for inducing and maintaining remission in inflammatory bowel diseases: from bedside...

There is growing interest in the role of dietary therapies in the management of inflammatory bowel diseases (IBDs), including Crohn's disease (CD) and ulcerative colitis (UC). This narrative review synthesizes current evidence on the nutritional composition and clinical implications of diets evaluated for IBD across different disease stages and phenotypes. In active CD, dietary strategies commonly focus on the exclusion of specific components believed to promote inflammation, such as food additives and ultra processed foods. This is in contrast to exclusive enteral nutrition or Crohn's disease exclusion diet (CDED) + partial enteral nutrition (PEN), which, despite containing food additives such as emulsifiers, remains the main established and efficacious dietary therapies for active CD. Some diets also restrict gluten and lactose during their initial phases. In active UC, dietary approaches emphasize the modulation of microbial metabolism, particularly by reducing colonic sulfide production and enhancing the production of short-chain fatty acids through reduced intake of animal-based foods and increased consumption of fermentable fibers and resistant starch. For maintenance of remission in both CD and UC, data supporting specific dietary approaches are currently limited. However, the emphasis shifts toward sustainability, favoring flexible, plant-based, minimally processed dietary patterns, such as the Mediterranean diet (MED). Future well-designed, adequately powered clinical trials are required to confirm efficacy, clarify long-term outcomes, and establish disease-specific dietary recommendations. Personalized dietary counseling by trained IBD dietitians, as part of the multidisciplinary team, remains central to integrating these approaches into care, optimizing adherence, and ensuring nutritional adequacy and optimal quality of life.