Objective The effects of dietary interventions on gut bacteria are ambiguous. Following a previous intervention study, we aimed to determine how differing diets impact gut bacteria and if bacterial profiles predict intervention response.
Design Sixty-seven patients with IBS were randomised to traditional IBS (n=34) or low fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAPs) (n=33) diets for 4 weeks. Food intake was recorded for 4 days during screening and intervention. Faecal samples and IBS Symptom Severity Score (IBS-SSS) reports were collected before (baseline) and after intervention. A faecal microbiota dysbiosis test (GA-map Dysbiosis Test) evaluated bacterial composition. Per protocol analysis was performed on 61 patients from whom microbiome data were available.
Results Responders (reduced IBS-SSS by ≥50) to low FODMAP, but not traditional, dietary intervention were discriminated from non-responders before and after intervention based on faecal bacterial profiles. Bacterial abundance tended to be higher in non-responders to a low FODMAP diet compared with responders before and after intervention. A low FODMAP intervention was associated with an increase in Dysbiosis Index (DI) scores in 42% of patients; while decreased DI scores were recorded in 33% of patients following a traditional IBS diet. Non-responders to a low FODMAP diet, but not a traditional IBS diet had higher DI scores than responders at baseline. Finally, while a traditional IBS diet was not associated with significant reduction of investigated bacteria, a low FODMAP diet was associated with reduced Bifidobacterium and Actinobacteria in patients, correlating with lactose consumption.
Conclusions A low FODMAP, but not a traditional IBS diet may have significant impact on faecal bacteria. Responsiveness to a low FODMAP diet intervention may be predicted by faecal bacterial profiles.
Trial registration number NCT02107625.
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Contributors SB: data acquisition, assemblage of database, interpretation of data and drafting and finalising of manuscript. Has approved the final draft submitted. LB: assemblage of database. Has approved the final draft submitted. HT: collection of study subject materials, interpretation of data and finalising of manuscript. Has approved the final draft submitted. SS, TL and LC: data acquisition. Have approved the final draft submitted. PL and HT: data acquisition and manuscript finalisation. Has approved the final draft submitted. LÖ: project planning, interpretation of data, drafting and finalising of manuscript. Has approved the final draft submitted. MS: project planning, interpretation of data, material acquisition, drafting and finalising of manuscript. Has approved the final draft submitted.
Funding The Swedish Medical Research Council (grants 13409, 21691 and 21692); AFA insurance (140330); VINNOVA (11-03475); The Marianne and Marcus Wallenberg Foundation, University of Gothenburg; Centre for Person-Centred Care (GPCC), Sahlgrenska Academy, University of Gothenburg; The Faculty of Medicine, University of Gothenburg.
Competing interests MS has received unrestricted research grants from Danone, and Ferring Pharmaceuticals and served as a Consultant/Advisory Board member for AstraZeneca, Danone, Nestlé, Chr Hansen, Almirall, Allergan, Albireo, Glycom and Shire, and as a speaker for Tillotts, Takeda, Menarini, Allergan, Shire and Almirall. HT has served as Consultant/Advisory Board member for Almirall, Allergan, Danone and Shire. LÖ has served as Consultant/Advisory Board member for Genetic Analysis, has received unrestricted research grants from AstraZeneca, and as a speaker for Takeda, AbbVie and Meda. PL has served as Consultant/Advisory Board member for Almirall, Allergan, Abbvie and Shire.
Ethics approval The regional ethics board.
Provenance and peer review Not commissioned; externally peer reviewed.
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