Faecal and urine metabolites, but not gut microbiota, may predict response to low FODMAP diet in irritable bowel syndrome

Aliment Pharmacol Ther. 2023 Aug;58(4):404-416.doi: 10.1111/apt.17609. Epub 2023 Jun 14.


Bridgette Wilson 1 2Tokuwa Kanno 3Rachael Slater 4Megan Rossi 1Peter M Irving 5 6Miranda C Lomer 1 2Chris Probert 4A James Mason 3Kevin Whelan 1


Author information

1Department of Nutritional Sciences, King's College London, London, UK.

2Department of Nutrition and Dietetics, Guys and St Thomas' NHS Foundation Trust, London, UK.

3King's College London, Institute of Pharmaceutical Science, London, UK.

4University of Liverpool, Institute of Systems, Molecular and Integrative Biology, Liverpool, UK.

5Department of Gastroenterology, Guys and St Thomas' NHS Foundation Trust, London, UK.

6School of Immunology and Microbial Sciences, King's College London, London, UK.


Background: The low FODMAP diet (LFD) leads to clinical response in 50%-80% of patients with irritable bowel syndrome (IBS). It is unclear why only some patients respond.

Aims: To determine if differences in baseline faecal microbiota or faecal and urine metabolite profiles may separate clinical responders to the diet from non-responders allowing predictive algorithms to be proposed.

Methods: We recruited adults fulfilling Rome III criteria for IBS to a blinded randomised controlled trial. Patients were randomised to sham diet with a placebo supplement (control) or LFD supplemented with either placebo (LFD) or 1.8 g/d B-galactooligosaccharide (LFD/B-GOS), for 4 weeks. Clinical response was defined as adequate symptom relief at 4 weeks after the intervention (global symptom question). Differences between responders and non-responders in faecal microbiota (FISH, 16S rRNA sequencing) and faecal (gas-liquid chromatography, gas-chromatography mass-spectrometry) and urine (1 H NMR) metabolites were analysed.

Results: At 4 weeks, clinical response differed across the 3groups with adequate symptom relief of 30% (7/23) in controls, 50% (11/22) in the LFD group and 67% (16/24) in the LFD/B-GOS group (p = 0.048). In the control and the LFD/B-GOS groups, microbiota and metabolites did not separate responders from non-responders. In the LFD group, higher baseline faecal propionate (sensitivity 91%, specificity 89%) and cyclohexanecarboxylic acid esters (sensitivity 80%, specificity 78%), and urine metabolite profile (Q2 0.296 vs. randomised -0.175) predicted clinical response.

Conclusions: Baseline faecal and urine metabolites may predict response to the LFD.

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