Helping a Patient Manage IBS and Diarrhea

When IBS is diarrhea-predominant, a doctor may prescribe an antimotility agent to assist patients with symptoms (1). He or she may also prescribe an antibiotic if the IBS is a result of small intestinal bacterial overgrowth (1).

As a dietary aid for patients, a nutritionist may suggest soluble fiber such as from oats because it can help act against symptoms such as diarrhea by helping bind fat and slow emptying of food from the stomach into the small intestine (2).

The soluble fiber can include prebiotics such as fructo-oligosaccharides or resistant maltodextrin, which support growth of healthy intestinal bacteria. The prebiotics taken in conjunction with probiotics particularly after antibiotic therpay may help with promoting the growth of the good bacteria. This integrative therapy can help to alleviate symptoms by promoting competition against small intestinal bacterial growth (3).

Nutrionists should recommend suspending intake of insoluble fiber such as from wheat and cereal grains and limiting poorly-digested carbohydrates and sugar alcohols as these can worsen symptoms (4). Patients may find benefit from following an exclusion diet whereas trigger foods are eliminated and then, if thought advisable, reintroduced gradually (4).


1. Kohlstadt I. Food and Nutrients in Disease Management. Boca Raton, FL: CRC Press, 2009.
2. Bijkerk CJ, de Wit NJ, Muris JWM, Whorwell PJ, Knottnerus JA, Hoes AW. Soluble or insoluble fibre in irratble bowel syndrome in primary care? Randomized placebo controlled trial. Brit Med Jour 2009;339:b3154. Available at Accessed on March 31, 2010.
3. American College of Gastroenterology (2008, October 10). How Effective Are Probiotics In Irritable Bowel Syndrome?. ScienceDaily. Available at­ /releases/2008/10/081006092656.htm. Accessed on March 31, 2010.
4. Heizer WD, Southern S, McGovern S. The role of diet in symptoms of irritable bowel syndrome in adults: a narrative view. J Am Diet Assoc. 2009 Jul;109(7):1204-1.

Published by David Despain, MS, CFS

David is a science and health writer living on Long Island, New York. He's written for a variety of publications including Scientific American, Outside Online, the American Society for Nutrition's (ASN) Nutrition Notes Daily, and Institute of Food Technologists' (IFT) Food Technology magazine and Live! blog. He's also covered new findings reported at scientific meetings including Experimental Biology, AAAS, AOCS, CASW, Sigma Xi, IFT, and others on his personal blog "Evolving Health." David is also an active member of organizations including the National Association of Science Writers (NASW), the American Association for the Advancement of Science (AAAS), the American Society for Nutrition, the Institute of Food Technologists, and the National Audubon Society. David has a master's degree in human nutrition from the University of Bridgeport, and a bachelor's degree in English from University of Illinois at Springfield. He also earned his Certified Food Scientist credential from the Institute of Food Technologists.

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