Using the Low-FODMAP Diet for IBS

Why the Low-FODMAP Diet Might Be Of Help for IBS

Woman eating cereal
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Researchers based in Australia have come up with a novel dietary approach for managing the symptoms of IBS. This approach involves the restriction of foods that contain certain carbohydrates, known as FODMAPS, that are found in common foods. The theory behind the low-FODMAP diet does not take on the question of what causes IBS, rather it looks at the role that FODMAP-containing foods play in triggering digestive symptoms in people who suffer from visceral hypersensitivity and motility dysfunction.

The FODMAP theory has been applied to both IBS and the inflammatory bowel diseases.

Why Do FODMAPs Cause Symptoms?

The acronym FODMAPs refers to Fermentable Oligo-, Di- and Mono-saccharides, and Polyols. FODMAP researchers have found that these short-chain carbohydrates and sugar alcohols are poorly absorbed by the small intestine and thus are rapidly set upon and fermented by bacteria within the digestive system, specifically the small intestine and the upper parts of the large intestine (proximal colon). 

Researchers in this area theorize that the rapid fermentation of these carbohydrates contributes to GI symptoms by creating a distention of the intestines in two ways - through a higher volume of liquid due to osmosis, and an increase in gas production. The researchers have been conducting ongoing studies to support their theory. They have been looking at the volume of liquid produced by high FODMAPs foods (measured in individuals with ileostomies) and gas produced (measured by hydrogen breath testing) and have then been comparing these results to liquid and gas production of low FODMAPs foods.

This increase in intestinal distension brought about by high FODMAPs foods is thought to be a contributing factor in various IBS symptoms:

How Does the Diet Help?

The FODMAP theory suggests that limiting the amount of high FODMAP foods should result in a decrease in these unpleasant digestive systems.

FODMAP researchers are consistently finding that the low-FODMAP diet is effective in reducing symptoms in approximately three quarters of IBS patients. Ongoing research is being conducted as to the accuracy of the components of this theory and the effectiveness of a low FODMAP diet in reducing digestive distress.


Gibson, P. & Shepherd, S. "Evidence-based dietary management of functional gastrointestinal symptoms: The FODMAP approach" Journal of Gastroenterology and Hepatology 2010 25:252-258.

Ong, D. "Manipulation of dietary short chain carbohydrates alters the pattern of gas production and genesis of symptoms in irritable bowel syndrome" Journal of Gastroenterology and Hepatology 2010 25:1366-1373

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