How do FODMAPs work?

Abstract

Disclosures: RS has received research funding from Lesaffre and Ironwood. He has also acted on advisory boards for Allergan, Commonwealth Diagnostics International, Danone, Ipsen, and Yuhan, and received speakers' fees from Menarini. AbstractMany patients report symptoms come on after eating, and experience with exclusion diets suggests that certainly poorly absorbed but rapidly fermentable carbohydrates may be responsible. While monomeric and short chain carbohydrate polymers exert osmotic forces and trap water in the small bowel with acceleration of transit, the longer polymer polymers such as inulin pass through the small bowel unaltered but are fermented in the colon where they may cause distension and symptoms. Recent developments in magnetic resonance imaging confirm the importance of fructose in stimulating small bowel water secretion and its negation by the presence of glucose. Fructans have no impact on the small intestine but cause colonic distension and symptoms including bloating.

Content of Poorly Absorbed Short‐Chain Carbohydrates (FODMAP) in Enteral Homemade Diets

“…When poorly absorbed, lactose may be detected by hydrogen testing, tolerance to lactose testing, or lactase activity associated to the biopsy of the small intestine or magnetic resonance imaging. In this situation, lactose should be considered a FODMAP for these individuals, because it promotes distension of the small intestine caused by the secretion of water into the intestinal lumen and the consequent bacterial fermentation of this disaccharide in the colon …”

“…Because the small intestine lacks hydrolases capable of breaking fructose–fructose bonds, and fructans cannot be transported by the epithelium, they are not absorbed. Consequently, the fructans ingested have no impact on the small intestine but are available for fermentation by intestinal bacteria and may trigger physiological symptoms similar to the ones of fructose in the intestinal lumen due to distension of the colon …”

“…In this situation, lactose should be considered a FODMAP for these individuals, because it promotes distension of the small intestine caused by the secretion of water into the intestinal lumen and the consequent bacterial fermentation of this disaccharide in the colon. 14,18,40 Studies show that fructose substantially increases the amount of water in the intestinal lumen, as well as increases the production of intestinal gases that contribute to abdominal distension. 19,40 Fruit juices naturally contain a high content of fructose, as well as apple, mango, pear, watermelon, honey, and corn syrup.…”

“…14,18,40 Studies show that fructose substantially increases the amount of water in the intestinal lumen, as well as increases the production of intestinal gases that contribute to abdominal distension. 19,40 Fruit juices naturally contain a high content of fructose, as well as apple, mango, pear, watermelon, honey, and corn syrup. 15,41 Fructose is absorbed through the epithelium of the small intestine by 2 mechanisms.…”

“…Consequently, the fructans ingested have no impact on the small intestine but are available for fermentation by intestinal bacteria and may trigger physiological symptoms similar to the ones of fructose in the intestinal lumen due to distension of the colon. 15,40 Legumes such as lentils, chickpeas and red beans, soy, and walnuts are dietary sources of significant galactans, such as raffinose and stachyose. 35,41 The importance of polyols as FODMAP is underestimated, but polyols are widely found in food.…”