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PLoS One. 2018 Jul 26;13(7):e0201410. doi: 10.1371/journal.pone.0201410. eCollection 2018.

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

Author information

The NIHR Nottingham Biomedical Research Centre (BRC) at Nottingham University Hospitals NHS Trust and the University of Nottingham, Nottingham, United Kingdom.
School of Life Sciences, University of Nottingham, Nottingham, United Kingdom.
Department of Clinical Microbiology, Nottingham University Hospitals NHS Trust, Nottingham, United Kingdom.
Nottingham Digestive Diseases Centre, School of Medicine, University of Nottingham, Nottingham, United Kingdom.
Immunobiology Research Program, University of Helsinki, Helsinki, Finland.
Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, United Kingdom.
Centre for Analytical Bioscience, Advanced Materials and Healthcare Technology Division, School of Pharmacy, University of Nottingham, Nottingham, United Kingdom.
Department of Nutritional Sciences, King's College London, London, United Kingdom.



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.


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.


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.


A low FODMAP diet reduces total bacterial count and gas production with little effect on colonic volume.

Conflict of interest statement

The authors have declared that no competing interests exist.

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