July 11, 2017
2 min read

Low FODMAP diet with prebiotic supplement improves IBS symptoms

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Bridgette Wilson
Bridgette Wilson

The combination of a low FODMAP diet and a prebiotic supplement resulted in significantly greater symptom improvement in patients with irritable bowel syndrome compared with those assigned to a sham diet and placebo in a three-arm parallel randomized controlled trial.

However, the addition of the prebiotic (B-galacto-oligosaccharide; B-GOS) did not increase Bifidobacteria as intended, which are reduced by the low FODMAP diet.

These findings were recently presented at the British Society of Gastroenterology Annual Meeting in Manchester.

The multicenter trial “demonstrated that the combination therapy of 1.4 g per day B-GOS prebiotic and the low FODMAP diet significantly improves symptoms of IBS compared to a group on a sham diet taking a placebo,” Bridgette Wilson, a research dietitian and PhD student at King’s College London, told Healio Gastroenterology. “This study also demonstrates for the first time that the effect of the low FODMAP diet on short chain fatty acids and stool pH occurs within just 7 days of starting the diet and these changes persist with dietary restriction.”

Wilson and colleagues randomly assigned 69 patients with IBS to receive a sham diet with placebo, a low FODMAP diet only, or a low FODMAP diet with the prebiotic supplement for 4 weeks. They evaluated symptoms before and after the intervention period, and tested stool samples for Bifidobacteria, short-chain fatty acids and pH at baseline and weeks 1 and 4.

The investigators saw significant differences between symptom relief at week 4 between controls (30.4%), those on the low FODMAP diet alone (50%) and those on the low FODMAP diet plus the prebiotic (66.7%; P = 0.046). The low FODMAP plus prebiotic group also had markedly improved individual IBS symptoms compared with the sham group, and post-hoc analysis showed especially significant differences in overall symptom relief between these two groups (P = .015).

Further, the investigators observed significant differences in Bifidobacteria across the three arms (P = .009), and post-hoc analysis showed significant differences between the low FODMAP plus prebiotic and sham groups at week 4 (P = .009).

They also noted that the low FODMAP group showed higher stool pH and lower butyrate at weeks 1 and week 4 compared with the sham group. Results were similar in the low FODMAP plus prebiotic vs. sham groups, but pH was not higher in the former until week 4.

“The low FODMAP diet is somewhat ‘anti-prebiotic’ in the effect it has on raising stool pH and reducing stool Bifidobacteria and short-chain fatty acids, and 1.4 g [per day] of B-GOS prebiotic is not sufficient to overcome the effect of the diet restriction on either Bifidobacteria or the colonic luminal environment,” Wilson concluded. – by Adam Leitenberger


Wilson B, et al. Abstract OC-026. Presented at: British Society of Gastroenterology Annual Meeting; June 19-22, 2017; Manchester.

Disclosures: Wilson reports that Clasado Biosciences, the manufacturer of the prebiotic, partially funded her PhD.