Which Diet Works Best for Patients with Irritable Bowel Syndrome?

Irritable Bowel Syndrome (IBS) affects about 10-15% of the population, and accounts for a very high percentage of visits to primary care physicians and GI specialists. The disorder impacts the large intestine – causing symptoms of abdominal pain, constipation, bloating, diarrhea, and gas. Because symptoms fluctuate so often, it is difficult to complete thorough and quality research to determine what type of diets help treat these symptoms best. Researchers find it problematic to enforce a strict routine of any particular diet because there is a greater chance of patients experiencing the placebo effect, meaning patients believe that simply making a small change as opposed to doing nothing at all can have a positive effect on their symptoms.

In recent years, a diet developed in Australia focused on reducing a variety of foods containing “FODMAPS” from patient’s diets. FODMAPS is a term to describe a large group of fermentable short-chain carbohydrates that further aggravate various IBS symptoms. The list includes a variety of food substances containing certain sugars, such as lactose and fructose, that feed gas-producing bacteria, and pull a lot of fluid into the intestine. By significantly reducing FODMAPs foods, such as beans, lactose, corn syrup sweeteners in soda and processed foods, and many others, patients can work with their dietitians to improve their quality of life with IBS.
The diet appeared to have a positive effect on patients with IBS, as many described a decrease in discomfort, abdominal pain, and other related symptoms. But how does this compare to the more “traditional” advice about IBS diet changes: namely, exercising portion control, and eliminating caffeine, gas-producing foods, and insoluble fiber?

Recently, a Swedish group reported a comparison of diets. In a blind study, patients with IBS were randomly assigned to two different diet regimens, and the results were very similar between the two diet approaches. The experiment compared a diet low in FODMAPS vs. a diet high or moderate in FODMAPS. It is unclear if combining certain parts of both diets would produce better results. Moreover, the study brought up a precaution: both diets resulted in people taking in fewer calories, as much as 400 fewer calories in the FODMAPS restricted diet. While this might be a positive for IBS patients who are overweight, patients of normal weight might deprive themselves of essential nutrients.

Bottom line: If you suffer from IBS and want to alleviate your symptoms, explore both diet options with your health care professional. Patients looking to try the FODMAPs approach can work with a qualified nutritionist or registered dietitian (RD) to develop a personalized plan that fits their lifestyle.

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Lena Bohn & colleagues reported in Gastroenterology, November 2015 (web: doi:10.1053/j.gastro.2015.07.056)

FODMAPS stands for: fermentable oligosaccharides, disaccharides, monosaccharides and polyols