A low FODMAP diet is associated with changes in the microbiota and reduction in breath hydrogen but not colonic volume in healthy subjects

PLoS ONE

Jul 2018

DOI: 10.1371/journal.pone.0201410

Citations:88

Influential Citations:7

Interventional (Human) Studies

Enhanced Details

Methods

Single-centre, parallel-group, double-blind randomized controlled trial in healthy adults (n=37). Randomized to maltodextrin (n=18) or oligofructose (n=19) supplementation while following a 7-day low FODMAP diet. Baseline ages: MD 23.5±2.9; OF 26.5±12.2. Gender distribution: MD 14M/4F; OF 11M/8F. Exclusions included pregnancy, inability to comply with diet, pre-existing GI disorders or IBS, antibiotics or probiotics in past 8 weeks, MRI contraindications.

Intervention

Low FODMAP diet for 7 days with supplementation of either oligofructose or maltodextrin (7 g twice daily).

Results

A 7-day low FODMAP diet reduced breath hydrogen and total microbial load; oligofructose supplementation reversed the hydrogen reduction and increased Bifidobacterium abundance, while maltodextrin did not. Colonic volume increased after the diet in both groups (approximately +90 ml for maltodextrin and +110 ml for oligofructose) with no significant between-group difference. Taxa shifts differed by supplement: maltodextrin reduced Bifidobacterium and increased Bilophila; oligofructose increased Actinobacteria (notably Bifidobacterium) and reduced Lachnospiraceae. Methane levels did not change significantly. Breath hydrogen and total gas production correlated with colonic volume and microbial diversity. Conclusion: A low FODMAP diet reduces total bacterial count and gas production with little effect on colonic volume. In healthy adults, changes in microbiota and gas production occur with minimal distension changes; symptom relief on low FODMAPs in IBS may be driven more by reduced microbial fermentation than by reduced colonic distension. To maintain beneficial bacteria during a low FODMAP diet, prebiotic supplementation (e.g., oligofructose) may offset reductions in Bifidobacterium.

Limitations

Small sample size (n=37 completed); short duration (7 days); exploratory microbiota/metabolomics analyses; healthy population limits generalizability to IBS or clinical settings; single-centre design; lack of measured clinical outcomes.

Abstract

Background & aims Ingestion of poorly digested, fermentable carbohydrates (fermentable oligo-, di-, mono-saccharides and polyols; FODMAPs) have been implicated in exacerbating intestinal symptoms and the reduction of intake with symptom alleviation. Restricting FODMAP intake is believed to relieve colonic distension by reducing colonic fermentation but this has not been previously directly assessed. We performed a randomised controlled trial comparing the effect of a low FODMAP diet combined with either maltodextrin or oligofructose on colonic contents, metabolites and microbiota. Methods A parallel randomised controlled trial in healthy adults (n = 37). All subjects followed a low FODMAP diet for a week and supplemented their diet with either maltodextrin (MD) or oligofructose (OF) 7g twice daily. Fasted assessments performed pre- and post-diet included MRI to assess colonic volume, breath testing for hydrogen and methane, and stool collection for microbiota analysis. Results The low FODMAP diet was associated with a reduction in Bifidobacterium and breath hydrogen, which was reversed by oligofructose supplementation. The difference in breath hydrogen between groups post-intervention was 27ppm (95% CI 7 to 50, P<0.01). Colonic volume increased significantly from baseline in both groups (OF increased 110ml (19.6%), 95% CI 30ml to 190ml, P = 0.01; MD increased 90ml (15.5%), 95% CI 6ml to 175ml, P = 0.04) with no significant difference between them. Colonic volumes correlated with total breath hydrogen + methane. A divergence in Clostridiales abundance was observed with increased abundance of Ruminococcaceae in the maltodextrin group, while in the oligofructose group, Lachnospiraceae decreased. Subjects in either group with high methane production also tended to have high microbial diversity, high colonic volume and greater abundance of methanogens. Conclusion A low FODMAP diet reduces total bacterial count and gas production with little effect on colonic volume. show less