Diet in Ulcerative Colitis: A Narrative Review of Its Role in Pathogenesis and Treatment.

Ulcerative colitis (UC) is a chronic inflammatory bowel disease influenced by genetic, immune, microbial, and environmental factors, with diet emerging as a key modifiable element. This narrative review examines how specific macronutrients, food additives, and dietary patterns affect UC pathogenesis, symptom control, and clinical outcomes. High intake of saturated fats, red and processed meats, and ultra-processed foods promotes dysbiosis and mucosal inflammation, while diets rich in fiber, resistant starches, and omega-3 fatty acids support gut barrier integrity and exert anti-inflammatory effects. The Mediterranean diet is associated with reduced disease activity, improved microbial diversity, and a lower incidence of pouchitis. Although the low-FODMAP diet can alleviate functional gastrointestinal symptoms, it lacks evidence for reducing inflammation and may adversely impact beneficial bacteria. Parenteral nutrition remains a valuable intervention in select cases with compromised oral or enteral intake. Micronutrient deficiencies, including iron, vitamin D, zinc, and magnesium, are common and should be routinely monitored. A personalized, dietitian-led approach that incorporates cultural preferences and digital tools may enhance dietary adherence and disease management. Further research is needed to define long-term effects of dietary interventions and integrate nutrition more fully into UC treatment algorithms.