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The Low FODMAPs Diet Theory for IBS

Why It Might Be Of Help


Updated March 24, 2014

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

A group of researchers based in Australia has proposed a theory regarding the use of a low FODMAP diet for IBS. The theory does not take on the question of what causes IBS, rather it looks at the role that certain 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.

FODMAP researchers have identified that short-chain carbohydrates, which are components of many foods, may be poorly absorbed by the small intestine and thus 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). These carbohydrates were given the acronym FODMAPs and refer to Fermentable Oligo-, Di- and Mono-saccharides, and Polyols.

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 FODMAP 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 FODMAP foods.

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

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 a 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.

Essential Reading from Dr. Bolen, Your IBS Guide:


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. et.al. "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

DISCLAIMER: The information contained on this site is for educational purposes only and should not be used as a substitute for diagnosis or treatment rendered by a licensed physician. It is essential that you discuss with your doctor any symptoms or medical problems that you may be experiencing.

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