FODMAP

Absorption

Some FODMAPs, such as fructose, are readily absorbed in the small intestine of humans via GLUT receptors. Absorption thus depends on the appropriate expression and delivery of these receptors in the intestinal enterocyte to both the apical surface, contacting the lumen of the intestine (e.g., GLUT5), and to the basal membrane, contacting the blood (e.g., GLUT2). Improper absorption of these FODMAPs in the small intestine leaves them available for absorption by gut flora. The resultant metabolism by the gut flora leads to the production of gas and potentially results in bloating and flatulence.

Although FODMAPs can cause certain digestive discomfort in some people, not only do they not cause intestinal inflammation, but they help prevent it because they produce beneficial alterations in the intestinal flora that contribute to maintaining good colon health.

FODMAPs are not the cause of irritable bowel syndrome or other functional gastrointestinal disorders, but rather a person develops symptoms when the underlying bowel response is exaggerated or abnormal.

Fructose malabsorption and lactose intolerance may produce IBS symptoms through the same mechanism, but unlike other FODMAPs, poor absorption of fructose is found in only a minority of people. Lactose intolerance is found in most adults, except for specific geographic populations, notably those of European descent. Many who benefit from a low FODMAP diet need not restrict fructose or lactose. It is possible to identify these two conditions with hydrogen and methane breath testing, thus eliminating the necessity for dietary compliance.

Sources in the diet

The significance of sources of FODMAPs varies through differences in dietary groups such as geography, ethnicity, and other factors. Commonly used FODMAPs comprise the following:

• oligosaccharides, including fructans and galactooligosaccharides
• disaccharides, including lactose
• monosaccharides, including fructose
• polyols, including sorbitol, xylitol, and mannitol

Fructans, galactans, and polyols

Sources of fructans

Sources of fructans include wheat, rye, barley, onion, garlic, Jerusalem and globe artichoke, beetroot, dandelion leaves, the white part of leeks, the white part of spring onion, brussels sprouts, savoy cabbage, and prebiotics such as fructooligosaccharides (FOS), oligofructose and inulin. Asparagus, fennel, red cabbage, and radicchio contain moderate amounts but may be eaten if the advised portion size is observed.

Sources of galactans

Pulses and beans are the main dietary sources (although green beans, canned lentils, sprouted mung beans, tofu (not silken), and tempeh contain comparatively low amounts). Supplements of the enzyme alpha-galactosidase may reduce symptoms, assuming the enzyme product does not contain other FODMAPs, such as polyol artificial sweeteners.

Sources of polyols

Polyols are found naturally in mushrooms, some fruit (particularly stone fruits), including apples, apricots, avocados, blackberries, cherries, lychees, nectarines, peaches, pears, plums, prunes, watermelon, and in some vegetables, including cauliflower, snow peas, and mange-tout peas. Cabbage, chicory, and fennel contain moderate amounts, but may be eaten in a low-FODMAP diet if the advised portion size is observed.

Polyols, specifically sugar alcohols, used as artificial sweeteners in commercially prepared food, beverages, and chewing gum, include isomalt, maltitol, mannitol, sorbitol, and xylitol.

Fructose and lactose

People following a low-FODMAP diet may be able to tolerate moderate amounts of fructose and lactose, particularly if they have lactase persistence.

Sources of fructose

Main article: Fructose malabsorption#Foods with high fructose content

Sources of lactose

Main article: Lactose intolerance#Dietary avoidance

Low-FODMAP diet

Main article: Low-FODMAP diet

A low-FODMAP diet consists of the global restriction of all fermentable carbohydrates (FODMAPs), and is recommended only for a short time. A low-FODMAP diet is recommended for managing patients with irritable bowel syndrome (IBS) and can reduce digestive symptoms of IBS, including bloating and flatulence.

Several studies have found a low-FODMAP diet to improve digestive symptoms in adults with irritable bowel syndrome, but its long-term use can have negative effects, because it has a detrimental impact on the gut microbiota and metabolome. It should only be used for short periods and under the advice of a specialist. More study is needed to evaluate its effectiveness in children with irritable bowel syndrome. Small studies (which are susceptible to bias) show little evidence of its effectiveness in treating functional symptoms of inflammatory bowel disease (IBD). More study is needed to assess the true impact of this diet on health.

Role in non-celiac gluten sensitivity

FODMAPs present in gluten-containing grains are a possible cause of gastrointestinal symptoms in people with non-celiac gluten sensitivity, either by themselves, or in combination effect with gluten and other proteins in gluten-containing cereals, such as amylase-trypsin inhibitors (ATIs). They are only minor sources of FODMAPs when eaten in common dietary amounts. Wheat and rye may comprise a major source of fructans when consumed in large amounts.

References

References

1. (June 2005). "Personal view: food for thought — western lifestyle and susceptibility to Crohn's disease. The FODMAP hypothesis". Alimentary Pharmacology & Therapeutics.
2. (September 2014). "Fermentable oligosaccharides, disaccharides, monosaccharides and polyols: role in irritable bowel syndrome". Expert Review of Gastroenterology & Hepatology.
3. (2016). "A low fermentable oligo-di-mono saccharides and polyols (FODMAP) diet reduced pain and improved daily life in fibromyalgia patients". Scand. J. Pain.
4. (May 2015). "Nonceliac gluten sensitivity". Gastroenterology.
5. (2015). "Assessing of Celiac Disease and Nonceliac Gluten Sensitivity". Gastroenterology Research and Practice.
6. (2018). "The Role of a Low Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyol Diet in Nonceliac Gluten Sensitivity". Gastroenterology Research and Practice.
7. (March 2017). "How to institute the low-FODMAP diet". Journal of Gastroenterology and Hepatology.
8. (August 2018). "Intestinal Absorption of Fructose". Annual Review of Nutrition.
9. (December 2015). "The Overlap between Irritable Bowel Syndrome and Non-Celiac Gluten Sensitivity: A Clinical Dilemma". Nutrients.
10. (2011). "Microbial induction of immunity, inflammation, and cancer". Frontiers in Physiology.
11. (2003). "Role of dietary fiber and short-chain fatty acids in the colon". Current Pharmaceutical Design.
12. (September 7, 2015). "Is fructose malabsorption a cause of irritable bowel syndrome?". Medical Hypotheses.
13. (October 2017). "Country, regional, and global estimates for lactose malabsorption in adults: a systematic review and meta-analysis". The Lancet. Gastroenterology & Hepatology.
14. (February 2010). "Evidence-based dietary management of functional gastrointestinal symptoms: The FODMAP approach". Journal of Gastroenterology and Hepatology.
15. (2014). "Advanced Therapy of Inflammatory Bowel Disease: Ulcerative Colitis". PMPH-USA.
16. (July 2023}}{{cite journal). "Food components and irritable bowel syndrome". Gastroenterology.
17. (2012-12-18). "The Monash University Low FODMAP diet". Monash University.
18. "New research: Enzyme therapy can help reduce symptoms in IBS patients sensitive to galacto-oligosaccharides (GOS) present in legumes, soy milk and nuts".
19. (July 2017). "A Systematic Review of the Effects of Polyols on Gastrointestinal Health and Irritable Bowel Syndrome". Advances in Nutrition.
20. (2016-04-17). "Polyols - A blog by Monash FODMAP {{!}} The experts in IBS - Monash Fodmap".
21. (January 2022). "Lactose Malabsorption and Presumed Related Disorders: A Review of Current Evidence". Nutrients.
22. (2022). "The low-FODMAP diet and the gluten-free diet in the management of functional abdominal bloating and distension". Front Nutr.
23. "What Is a Low-FODMAP Diet". WebMD.
24. (May 2018). "Does a low FODMAPs diet reduce symptoms of functional abdominal pain disorders? A systematic review in adult and paediatric population, on behalf of Italian Society of Pediatrics". Italian Journal of Pediatrics.
25. (April 2014). "Mechanisms and efficacy of dietary FODMAP restriction in IBS". Nature Reviews. Gastroenterology & Hepatology.
26. (April 2016). "Does a diet low in FODMAPs reduce symptoms associated with functional gastrointestinal disorders? A comprehensive systematic review and meta-analysis". European Journal of Nutrition.
27. (June 2015). "Systematic review: dietary fibre and FODMAP-restricted diet in the management of constipation and irritable bowel syndrome". Alimentary Pharmacology & Therapeutics.
28. (May 2016). "A healthy gastrointestinal microbiome is dependent on dietary diversity". Molecular Metabolism.
29. (August 2017). "The low FODMAP diet: recent advances in understanding its mechanisms and efficacy in IBS". Gut.
30. (February 2009). "Reduction of dietary poorly absorbed short-chain carbohydrates (FODMAPs) improves abdominal symptoms in patients with inflammatory bowel disease-a pilot study". Journal of Crohn's & Colitis.
31. (October 2014). "Diet and inflammatory bowel disease: review of patient-targeted recommendations". Clinical Gastroenterology and Hepatology.
32. (2015). "Assessing of Celiac Disease and Nonceliac Gluten Sensitivity". Gastroenterology Research and Practice.
33. (2013). "Non-celiac gluten sensitivity: questions still to be answered despite increasing awareness". Cellular and Molecular Immunology.