Patients with quiescent inflammatory bowel disease (IBD) who consumed a diet low in dietary fermentable carbohydrates reported significant improvements in specific symptom scores and symptom relief compared with patients who followed a control diet, according to the results of a trial published in Gastroenterology. The abundance of particular gut microbes believed to regulate immune response were reduced in fecal samples from participants on the low-FODMAP (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols) diet compared with those on the control diet.

The investigators performed a single-blind trial at 2 gastroenterology clinics in the United Kingdom to assess the effects of a low-FODMAP diet in patients with quiescent Crohn disease or ulcerative colitis who had persistent gut symptoms. The primary outcome was change in inflammatory bowel syndrome (IBS) Severity Scoring System. Secondary outcomes included evaluation of health-related quality of life and the intestinal microbiome and circulating markers of inflammation using stool and blood samples, respectively.

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In total, 52 patients were randomly assigned (1:1) to a diet low in FODMAPs (n=27) or a control diet (n=25) for 4 weeks. More patients on the low-FODMAP diet reported better relief of gut symptoms than those on the control diet (52% [14/27] vs 16% [4/25]; P =.007). Patients on the low-FODMAP diet had a greater reduction in IBS Severity Scoring System score than those on the control diet (mean reduction, 67 vs 34; P =.075). Patients on the low-FODMAP diet also had higher health-related quality of life scores than patients on the control diet (mean, 81.9 vs 78.3, P =.042).

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Patients on the low-FODMAP diet had significantly lower numbers of microbes believed to regulate immune response (Bifidobacterium adolescentis, Bifidobacterium longum, and Faecalibacterium prausnitzii) than patients on the control diet. Microbiome diversity and markers of inflammation did not differ between the groups.

Overall, 6 adverse events occurred during the trial. IBD relapse occurred in 2 participants (1 in each group). One participant started antibiotics unrelated to IBD (FODMAP diet). One participant experienced abdominal pain that resolved after 2 days (control diet). Flulike symptoms and sinusitis occurred in 1 participant in each group.

Limitations included sample size and study duration.

The authors concluded, “that a 4-week low FODMAP diet with expert advice and intensive follow-up is safe and effective in the management of persistent gut symptoms in quiescent IBD, but caution should be taken in longer term use.”


KW and MCL are the co-inventors of a mobile application to assist patients following low FODMAP diet. KW has received consultancy fees from Danone, and a research grant from Clasado.


Cox SR, Lindsay JO, Fromentin S, et al. Effects of low-FODMAP diet on symptoms, fecal microbiome, and markers of inflammation in patients with quiescent inflammatory bowel disease in a randomized trial [published online October 2, 2019]. Gastroenterology. doi:10.1053/j.gastro.2019.09.024