Table 1.
High-FODMAP Categories, Mechanism of Action, and Major Food Sources to Avoid. a
| Categories | Mechanism of action | Major food sources |
|---|---|---|
| Oligosaccharides | ||
| Fructans (oligo-fructose, inulin, fructo-oligosaccharides) | The fructans cannot hydrolyze the fructose bond food in the small intestine. It enters the colon causing fermentation by colonic bacteria and causes IBS symptoms | Wheat, onion, garlic |
| Galacto-oligosaccharides | The galactose-galactose molecules in the small intestine also cannot be hydrolyzed in the small intestine and cause similar symptoms as fructans | Chickpeas (including hummus), lentils, pulses (red kidney beans) |
| Inulin-type fructans and galacto-oligosaccharides | These offer prebiotic function and, therefore, provide health benefits | |
| Disaccharides | ||
| Lactose | Lactose is a disaccharide of glucose and galactose. It is absorbed in the brush border of the proximal small intestine. When there is no function or reduced activity of the lactase enzymes, lactose is not broken down to glucose and galactose. The lactose remains malabsorbed, causing increased production of short-chain fatty acids, methane, and hydrogen, leading to increased gas production, flatulence, and distension of both the small and large intestines | Milk, milk products |
| Monosaccharides | ||
| Fructose (in high concentrations or excess of glucose) | Fructose, in the presence of glucose is readily absorbed from the small intestine. However, more fructose content in the diet can lead to malabsorption causing pain, abdominal distension, and bloating in patients with visceral hypersensitivity and IBS | Large volumes of fruit juice (watermelon, pineapple, pears, apple), high-fructose corn syrup; mango, fig, honey (contains excess of glucose) |
| Polyols | ||
| Sorbitol and mannitol | Polyols are reduced-calorie carbohydrate sweeteners or sugar alcohols. These polyols are slowly absorbed from the small intestine, but when they reach the large intestine, they induce an osmotic effect (drawing water content into the bowel). Can cause laxative effect in addition to gut bacteria fermentation and gas production | Prunes, mushrooms, avocado, cauliflower, and apples; the substance added to sugar-free foods such as pudding and gelatin |
| Xylitol, isomalt | Same action as sorbitol and mannitol | Artificial sweetener added in some sugar-free chewing gums, mints, and sweets |