The Different FODMAP Types for IBS Symptoms

FODMAPs are carbohydrates found in ordinary foods that have been associated with contributing to symptoms in people who have IBS. The low-FODMAP diet has strong research for its effectiveness in reducing IBS symptoms when IBS patients restrict foods that are high in FODMAPs from their diet.

Glass of milk with caution tape in front of it
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The Five FODMAP Types

1. Fructans: Fructans are found primarily in wheat, many vegetables, (most notably garlic and onions), and the food additives FOS and inulin. Fructans are non-digestible and thus are available to be acted upon by gut bacteria. The fermentation that results offers some health benefits but can contribute to unwanted symptoms in a person who has IBS.

2. Fructose: Fructose is the sugar found in many fruits, honey, and high fructose corn syrup. Fructose malabsorption is only a problem for some IBS patients.

3. GOS: GOS stands for galactooligosaccharides, which are sometimes called galactans. GOS can be found in legumes, including beans, chickpeas, and lentils. Like fructans, GOS are non-digestible and thus have similar effects on the body and in IBS patients.

4. Lactose: Lactose is the sugar found in milk and other dairy products. Not all IBS patients are lactose intolerant. Foods also vary widely in lactose content, and therefore, some lactose-containing foods are allowed on the low-FODMAP diet.

5. Polyols: Polyols are sugar alcohols with scientific names that typically end in "- ol." They are found naturally in some fruits, such as blackberries, and vegetables, such as cauliflower and mushrooms, and are often used as artificial sweeteners. The researchers from Monash University break down the classification of polyols into mannitol and sorbitol. (Note: not all things ending in "-ol" are polyols.)

People who have IBS are not all reactive to every FODMAP type. Therefore, a key part of the diet is the re-introduction of each of these FODMAP types after an elimination phase. Each type is re-introduced into the diet in a systematic way to assess for tolerance. The ability to pinpoint which FODMAP types are troublesome allows the individual to eat as wide a variety of foods as being tolerable. It is optimal to go through the elimination and challenge phases of the diet under the care of a qualified dietary professional.

The Monash University Low-FODMAP Diet App is an excellent resource for identifying the specific FODMAP content of common foods.

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  1. The Ohio State University Wexner Medical Center. Should you avoid eating fructans? Updated March 22, 2019.

  2. Monash University. Enzyme therapy can help reduce symptoms in IBS patients sensitive to galacto-oligosaccharides (GOS). Updated November 16, 2017.

  3. Xiong L, Wang Y, Gong X, Chen M. Prevalence of lactose intolerance in patients with diarrhea-predominant irritable bowel syndrome: data from a tertiary center in southern ChinaJ Health Popul Nutr. 2017;36(1):38. Published 2017 Nov 21. doi:10.1186/s41043-017-0113-1

  4. Monash University. What are the polyols? Updated April 17, 2016.

  5. Tuck C, Barrett J. Re-challenging FODMAPs: the low FODMAP diet phase twoJ Gastroenterol Hepatol. 2017;32 Suppl 1:11–15. doi:10.1111/jgh.13687