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

Abstract

Background & aimsIngestion 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.MethodsA 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.ResultsThe 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.ConclusionA low FODMAP diet reduces total bacterial count and gas production with little effect on colonic volume.

A systematic review of the association between fibromyalgia and functional gastrointestinal disorders

“…Consuming a diet that is low in fermentable compounds has been shown to be effective in the management of IBS (46,47) including in subjects with fibromyalgia (48). Lowering the intake of fermentable foods is known to alter gut bacterial populations (49), and as yet the effect of such a diet on global symptoms of fibromyalgia is unexplored. Of note, investigators tended to regard IBS as a single entity, rather than a condition with several subtypes, a shortcoming which has been reported previously (50).…”

Review article: biological mechanisms for symptom causation by individual FODMAP subgroups ‐ the case for a more personalised approach to dietary restriction

“…have been shown to have a lower abundance of Bifidobacterium species in faecal samples compared to those on a sham diet. 3,59 Coadministration of multi-strain probiotic as well as oligofructose 59 was able to increase the numbers of Bifidobacterium species but did not contribute to further symptom alleviation. 3 Alterations to types and quantity of bacteria will likely impact on gas production and possibly other metabolites and hence colonic adaptation via pre-or probiotic supplementation could be a future therapy to mitigate effects of FODMAPs.…”

Nutraceuticals as modulators of gut microbiota: Role in therapy

“…Given the prebiotic effects of oligosaccharides (discussed later) on important components of the normal microbiome, such as lactobacilli and bifidobacteria, as well as their metabolic products, such as short‐chain fatty acids (SCFAs), the long‐term effects of the low FODMAP diet were of some concern. Changes in the faecal microbiome have, indeed, been described in relation to this diet with a reduction in bifidobacteria being most notable (Halmos et al, ; Huaman et al, ; McIntosh et al, ; Sloan et al, ; Staudacher et al, ); the clinical impact of these changes in the long term, in particular, remain unclear. The literature on the low FODMAP diet does provide an example of the potential benefits of a nutraceutical intervention; in this case a probiotic.…”

“…ble(Halmos et al, 2015;Huaman et al, 2018;McIntosh et al, 2017;Sloan et al, 2018;Staudacher et al, 2017); the clinical impact of these changes in the long term, in particular, remain unclear. The literature on the low FODMAP diet does provide an example of the potential benefits of a nutraceutical intervention; in this case a probiotic.…”