Cutting Out Carbs May Not Curb IBS Symptoms

A new data review finds little evidence to suggest that avoiding certain types of dietary carbohydrate will lessen the symptoms of irritable bowel syndrome (IBS).

After evaluating available published evidence as well as the three United Kingdom guidelines on the management of IBS, a team from the Drug and Therapeutics Bulletin (dtb) found that all the trials provide “some evidence” that IBS patients feel some of their symptoms are reduced by adhering to the FODMAP diet.
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The FODMAP diet is based on the observation that certain types of short-chain carbohydrates are poorly absorbed by the small intestine, and that IBS symptoms become worse when these carbs are eaten. These short-chain carbohydrates are present in wheat, onions, and legumes, and are also found in milk, honey, apples, and high-fructose corn syrup, as well the artificial sweeteners used in confectionary. These carbs ferment quickly in the gut, increasing water volume and gases.

The dtb team notes that 1 study indicates the diet changes the profile of the bacteria in the gut, although the clinical implications and long-term effects of this are unclear, adding that data to support the use of a low FODMAP diet as an effective treatment for treating control symptoms “is based on a few relatively small, short-term unblended or single-blinded controlled trials of varying duration.” In addition, dietary manipulation has its downside, with some unable to maintain a balanced diet when trying dietary exclusions, for example.

Ultimately, dtb recommends that suggesting a FODMAP diet for motivated patients that have seen other treatments fail to relieve symptoms should only be done with the supervision of a dietitian or specialist in the area of dietary intervention.

However, “we believe that patients should be advised that there is very limited evidence for [the FODMAP diet’s] use, the ideal duration of treatment has not been assessed in a clinical trial, and its place in the management of IBS has not been fully established.”

—Mark McGraw

Reference

Does a low FODMAP diet help IBS? DTB. 2015 [epub ahead of print] doi:10.1136/dtb.2015.8.0346.