Gut microbiota associations with diet in irritable bowel syndrome and the effect of low FODMAP diet and probiotics

Summary Background and Aims Diet is both a modulator of the gastrointestinal microbiota and an important therapy in irritable bowel syndrome (IBS). We aimed to comprehensively (i) identify diet-microbiota associations in adults with IBS consuming habitual diet; (ii) assess the impact of two nutritional interventions on the microbiota; and (iii) determine whether baseline microbiota can predict clinical response to diet or probiotic intervention. Methods Data were analyzed from 95 individuals with IBS participating in a previously published 4-week 2x2 factorial design randomized controlled trial investigating the impact of the low FODMAP diet (LFD) and co-administration of a probiotic. Diet was assessed at four hierarchical levels and partial 16S rRNA gene sequencing was used to profile the microbiota. Results There were numerous diet-microbiota associations especially at the nutrient level, including a negative association between protein and Bifidobacterium abundance (rs= -0.358, p Conclusions Although diet modifies the gut microbiota, bivariate correlation analysis may only provide a limited explanation of the complex diet interactions with individual gut bacteria in IBS. Some diet interventions modify the microbiota in IBS. Registered under ISRCTN registry identifier no. ISRCTN02275221.