FODMAPs, but Not Gluten, Affect Symptoms and the Fecal Environment in Subjects With Irritable Bowel Syndrome. A Double Blinded-Randomized Three-Way Crossover Study

Abstract

Abstract Objectives Irritable bowel syndrome (IBS) symptoms have been associated with fermentable oligo-, di-, monosaccharides and polyols (FODMAPs) as well as gluten. We aimed to evaluate the effects of provocations with diets rich in such components on IBS symptoms. We further aimed to study effects of FODMAPs and gluten on microbiota and if the microbiota composition was related to the severity of IBS symptoms. Methods A double-blind, placebo-controlled, randomised three-way crossover design (n = 110) was conducted. From run-in and throughout the study, IBS subjects maintained a diet with minimal FODMAP content and no gluten. Participants were block-randomised to one-week interventions with FODMAPs (50 g/day), gluten (17.3 g/day) or placebo, separated by one week of wash-out. Fecal samples were collected after each study week and analyzed for gut microbiota composition by sequencing of 16S rRNA gene amplicons. IBS symptoms were monitored by the IBS severity scoring system (IBS-SSS). Results In subjects with moderate to severe IBS (n = 103), FODMAPs caused higher total IBS-SSS (mean [SE] = 240 [9]) than placebo (208 [9]; p = 0.00056) or gluten (198 [9]; p = 0.013), but with no difference between gluten and placebo (p = 1.0). Relative abundance of Anaerostipes, Bifidobacterium and Faecalibacterium were higher after FODMAP compared to placebo. We found no difference in gut microbiota composition between gluten and placebo and no significant correlations between genera and severity of IBS-SSS. Conclusions In subjects with IBS, FODMAPs had an adverse but modest effect on typical IBS symptoms, whereas gluten had no effect. The microbiota composition was affected by the FODMAP but not the gluten intervention, in comparison to placebo. None of these differences were correlated to the severity of symptoms reflected in IBS-SSS, suggesting no apparent link between gut microbiota composition and IBS symptoms following intervention. Funding Sources Formas and the Swedish Research Council.