Malnutrition is most common in which form of inflammatory bowel disease?

• A. Ulcerative colitis
• B. Crohn's disease
• C. Microscopic colitis
• D. Collagenous colitis

Answer: (B)

Malnutrition in inflammatory bowel disease is driven by where the disease sits and how much of the absorptive surface is affected. Crohn's disease often involves the small intestine, especially the terminal ileum, where most nutrient absorption occurs. Inflammation there leads to malabsorption of fats and fat-soluble vitamins, iron, and B12, and can be compounded by strictures or fistulas that reduce absorptive surface. The resulting nutrient losses, plus decreased intake during flares and a heightened catabolic state, make malnutrition more likely. Ulcerative colitis affects the colon, where absorption is less critical for overall nutrition, so malnutrition is less common, though severe disease can still cause problems. Microscopic and collagenous colitis mainly cause diarrhea without substantial malabsorption. That combination makes Crohn's disease the form most associated with malnutrition.