OC-026 Prebiotic b-galacto-oligosaccharides in conjunction with the low fodmap diet improves symptoms of irritable bowel syndrome but does not prevent decline of bifidobacteria: a randomised controlled trial

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Dietary restriction of fermentable oligo-, di-, mono -saccharides and polyols (low FODMAP diet, LFD) is widely used for the management of irritable bowel syndrome (IBS), however it reduces gastrointestinal (GI) bifidobacteria. B-galacto-oligosaccharide (B-GOS; HOST-G904) are prebiotics that reduce symptoms and increase bifidobacteria in IBS however the combination of the two therapies has not previously been investigated.


This randomised controlled trial aimed to investigate whether: 1) IBS symptoms improved on LFD supplemented with B-GOS compared to control; and 2) B-GOS could prevent the reduction of GI bifidobacteria seen in patients following the LFD. Adults fulfilling Rome criteria for IBS were screened (n=130). Sixty-nine patients were recruited to a multicentre 3-arm parallel RCT and were randomised to: control (sham diet/placebo), LFD only (LFD/placebo) or LFD plus B-GOS (LFD/B-GOS) for four weeks. Validated questionnaires were used to assess GI symptoms at week 0 and week 4 and a stool sample collected for analysis at week 0, week 1 and week 4. Stool were analysed for bifidobacteria using fluorescent in situ hybridisation, and short-chain fatty acids (SCFA) and pH were measured using gas chromatography and pH probe respectively. Logistic regression, and ANOVA/ANCOVA (with post-hoc correction) were used to determine differences across the three groups.


At week 4 adequate relief of IBS symptoms differed significantly between control (30.4%), LFD (50%) and LFD/B-GOS (66.7%) (p=0.046), with post-hoc differences specifically between control and LFD/B-GOS (p=0.015). Individual IBS symptoms were more markedly improved in the LFD/B-GOS group compared to control. Bifidobacteria (log10/g dry weight) also differed across the groups (control 9.8, LFD 9.6, LFD/B-GOS 9.5; p=0.009), with post-hoc differences between the LFD/B-GOS and control at week 4 (p=0.009) Higher stool pH, and lower butyrate at week 1 and week 4 were observed in the LFD vs control diet group. Similar differences were observed in the LFD/B-GOS vs control diet group although pH was not higher than control until week 4.


Symptoms of IBS markedly improved during LFD supplemented with B-GOS prebiotic, suggesting a synergy between the two therapies. The LFD significantly impacts the GI luminal environment within the first seven days and these changes persist with diet restriction, however addition of a low dose prebiotic does not overcome the effect of diet on bifidobacteria.

Disclosure of Interest

B. Wilson Conflict with: BW is the recipient of a PhD fellowship awarded by Clasado BioSciences., M. Rossi: None Declared, G. Parkes: None Declared, Q. Aziz: None Declared, S. Anderson: None Declared, P. Irving: None Declared, M. Lomer: None Declared, K. Whelan: None Declared

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