ß-Galactooligosaccharide in Conjunction With Low FODMAP Diet Improves Irritable Bowel Syndrome Symptoms but Reduces Fecal Bifidobacteria

Am J Gastroenterol. 2020 May 20. doi: 10.14309/ajg.0000000000000641. Online ahead of print.

Bridgette Wilson 1 2, Megan Rossi 1, Tokuwa Kanno 3, Gareth C Parkes 4, Simon Anderson 5, A James Mason 3, Peter M Irving 5, Miranda C Lomer 1 2, Kevin Whelan 1


Author information

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

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

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

4Department of Gastroenterology, Barts Health NHS Trust, London, United Kingdom.

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


Introduction: The low FODMAP diet (LFD) reduces symptoms and bifidobacteria in irritable bowel syndrome (IBS). β-galactooligosaccharides (B-GOS) may reduce the symptoms and increase bifidobacteria in IBS. We investigated whether B-GOS supplementation alongside the LFD improves IBS symptoms while preventing the decline in bifidobacteria.

Methods: We performed a randomized, placebo-controlled, 3-arm trial of 69 Rome III adult patients with IBS from secondary care in the United Kingdom. Patients were randomized to a sham diet with placebo supplement (control) or LFD supplemented with either placebo (LFD) or 1.4 g/d B-GOS (LFD/B-GOS) for 4 weeks. Gastrointestinal symptoms, fecal microbiota (fluorescent in situ hybridization and 16S rRNA sequencing), fecal short-chain fatty acids (gas-liquid chromatography) and pH (probe), and urine metabolites (H NMR) were analyzed.

Results: At 4 weeks, adequate symptom relief was higher in the LFD/B-GOS group (16/24, 67%) than in the control group (7/23, 30%) (odds ratio 4.6, 95% confidence interval: 1.3-15.6; P = 0.015); Bifidobacterium concentrations (log10 cells/g dry weight) were not different between LFD and LFD/B-GOS but were lower in the LFD/B-GOS (9.49 [0.73]) than in the control (9.77 [0.41], P = 0.018). A proportion of Actinobacteria was lower in LFD (1.9%, P = 0.003) and LFD/B-GOS (1.8%, P < 0.001) groups than in the control group (4.2%). Fecal butyrate was lower in the LFD (387.3, P = 0.028) and LFD/B-GOS (346.0, P = 0.007) groups than in the control group (609.2).

Discussion: The LFD combined with B-GOS prebiotic produced a greater symptom response than the sham diet plus placebo, but addition of 1.4 g/d B-GOS did not prevent the reduction of bifidobacteria. The LFD reduces fecal Actinobacteria and butyrate thus strict long-term use should not be advised.

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