High-FODMAP Foods and Ulcerative Colitis

FODMAP is an acronym for four families of carbohydrate. Oligosaccharides are the fructans in wheat, onion, and garlic and the GOS in beans, lentils, and hummus. The disaccharide is lactose, which has its own page. The monosaccharide is fructose in excess of glucose, as in apples, pears, mango, honey, watermelon, and apple juice. Polyols are sugar alcohols: sorbitol in apples, pears, and cherries, mannitol in mushrooms. All are poorly absorbed in the small intestine, so they pull water in and arrive in the colon ready to ferment, and the resulting gas and distension hurt more in an inflamed or hypersensitive colon.

The evidence here is better than for most diet ideas in UC. Randomized trials of the low-FODMAP diet in IBD patients in remission with lingering gut symptoms found improvements in symptoms and quality of life, with no change in inflammation markers. The food-by-food numbers come from laboratory testing programs, which is why portion matters on this page: sweet corn tests moderate at half a cob and high at a full one, and a small serving of lentils tests low. The diet also reduces some beneficial bacteria, the main reason it is meant to be temporary.

The full protocol has three phases: restrict for two to six weeks, reintroduce one family at a time, then keep only the restrictions that earned their place. A cheaper solo version is to drop the family you eat most, usually fructans from onion, garlic, and wheat, for two weeks and see what changes. Doing it during a flare muddies everything; it is a remission tool.

Avoid rows on this page: apple, apple juice, cherries, corn, dried fruit, garlic, kombucha, onions, sugar-free gum. The caution rows are mostly dose-dependent: beans, lentils, hummus, honey, mango, pears, watermelon, mushrooms, oat milk, spinach in large portions, and bell peppers, where red tests high and green low. Applesauce is usually-OK because a serving carries only a little sorbitol.