Dietary Fiber for IBS

There is an article on dietary considerations for IBS (Algera et al., 2019) that you might find interesting.  The authors of this article extracted the findings from all the English-language research studies in the PubMed database on IBS and diet and wrote them up in a chronological summary describing the evolution of recommendations from 1977 to 2019.  When they were searching the database to find all these studies, they also looked specifically for studies on FODMAPs, lactose, fructose, fructan, low-carb, and gluten, and for studies looking at a set of guidelines for doctors to follow with IBS patients called the NICE guidelines. 

 

The biggest recommendation they landed on was to ensure adequate dietary fiber, such as that found in whole grains.  They found a systematic review of 14 randomized controlled trials that concluded soluble fiber was helpful for IBS symptoms (Moayyedi et al., 2014).  Another recommendation they looked at was the low FODMAP diet.  They discuss several studies that showed this diet to be helpful, but conclude that more research needs to be done, and they had concerns about the possibility that this diet could be detrimental to the population of beneficial bacteria in the digestive tract.  They also concluded that both the low-carb diet and the gluten-free diet need more research, although the gluten-free diet could be helpful for patients who also have non-celiac gluten sensitivity.  They did not find support for recommending a low-lactose diet, unless the patient is also lactose-intolerant. 

 

They also point out that there may be dietary recommendations that help some individuals with IBS but that don’t work for others, and that a future area of research could work on figuring out ways to determine which diets might work for a person based on their microbiome.  This article is a narrative review, which means that there is potential for the authors’ opinions to be reflected in their presentation of all the research done so far on diets for IBS.  But they state that they considered all the studies they could find on the topic, showing an intention to be unbiased and to bring together all the existing evidence, so the article is able to direct us to research that showed promising results, and it is also helpful to see which diets have gotten considerable attention even if they have not yet been shown to be effective.  A patient with IBS will probably have heard about all these diets and be curious about whether they work or not. 

 

Clinicians wanting to recommend soluble fiber to their patients after reading this article could look at the systematic review they cited (Moayyedi et al., 2014), which goes through a much more rigorous evaluation of evidence quality, and they could even go and look at each of the 14 randomized controlled trials to see exactly what kind of fiber was tested and how they measured the improvements.  Ispaghula husk was the fiber product most often tested and found to be effective. 

 

References:

 

Algera, J., Colomier, E., & Simrén, M. (2019). The Dietary Management of Patients with Irritable Bowel Syndrome: A Narrative Review of the Existing and Emerging Evidence. Nutrients, 11(9). 

 

Moayyedi, P., Quigley, E. M. M., Lacy, B. E., Lembo, A. J., Saito, Y. A., Schiller, L. R., Soffer, E. E., Spiegel, B. M. R., & Ford, A. C. (2014). The effect of fiber supplementation on irritable bowel syndrome: a systematic review and meta-analysis. The American Journal of Gastroenterology, 109(9), 1367–1374.