Consumption of a Low Fermentable Oligo-, Di-, Mono-saccharides, and Polyols Diet and Irritable Bowel Syndrome: A Systematic Review

Consumption of low dietary fermentable carbohydrates, including fermentable oligo-, di-, mono-saccharides, and polyols (FODMAP) has been hypothesized to improve symptoms of irritable bowel syndrome (IBS). This study was done to summarize findings from earlier evidence on the effect of a low FODMAP diet (LFD) on the symptoms of IBS. We searched in ISI Web of Knowledge, PubMed, Scopus, and Google Scholar using the following keywords: “FODMAP” OR “oligosaccharides” OR “disaccharides” OR “Monosaccharaides” in combination with “irritable bowel syndrome” or “IBS” or “Gastrointestinal Disease.” The reference lists of the relevant papers were also examined to avoid missing any publication. No time and language restrictions were applied. The relevant studies were selected through an independent search by two investigators. Overall, 778 relevant articles were found in our initial search. After reviewing title and abstracts, 763 papers were excluded from this review and 15 studies were included. All published studies were interventional studies in which patients with IBS had been recommended or randomized to receive a LFD. Three studies had quasi-experimental design, 9 were parallel randomized clinical trial and 3 studies were of randomized cross-over trials. These studies were conducted between 2009 and 2016. Nine studies were done in Europe, 2 in US, 3 in Australia, and one in Asia. Sample sizes of these studies were varied from 12 to 182. All studies had been conducted on both sexes, with the majority of participants as women (>70%). The age range was between 11 and 74 years in different studies. One study was performed on children, 9 on adults, and 5 others were in young-to-middle age groups. Duration of intervention was varied from 2 days to 16 months (2 studies with <1 week, and others with more than 2 weeks). Eight studies had suggested a significant effect of LFD on the improvement of all IBS symptoms, and 1 study had reported improvement in all symptoms except for constipation. One study had not found a significant difference between LFD and lactobacillus GG on IBS symptoms. Another paper had reported no significant effect of an LFD on IBS compared with the traditional IBS diet. The other paper had reported LFD improved 75% of diarrhea. Adherence to an LFD was not associated with the severity of symptoms. It is concluded that consumption of an LFD might reduce symptoms of IBS; however, further studies are required to shed light on inconsistencies in this field.