Effects of a prebiotic formulation on the composition of the faecal microbiota of people with functional constipation

Abstract

Purpose: Prebiotics are defined as substances which selectively promote beneficial gut microbes leading to a health benefit for the host. Limited trials have been carried out investigating their effect on the microbiota composition of individuals afflicted by functional constipation with equivocal outcomes. In a 21-day randomised, controlled clinical trial involving 61 adults with functional constipation, a prebiotic formulation with partially hydrolysed guar gum and acacia gum as its main ingredients, significantly increased complete spontaneous bowel motions in the treatment group. This follow-up exploratory analysis investigated whether the prebiotic was associated with changes to the composition, richness, and diversity of the faecal microbiota.

Methods: Participants provided a faecal specimen at baseline and on day 21 of the intervention period. Whole genome metagenomic shotgun sequencing comprehensively assessed taxonomic and functional composition of the microbiota.

Results: Linear mixed effects regression models adjusted for potential confounders showed a significant reduction in species richness of 28.15 species (95% CI - 49.86, - 6.43) and Shannon diversity of 0.29 units (95% CI - 0.56, - 0.02) over the trial period in the prebiotic group. These changes were not observed in the control group, and functional composition was unchanged in both groups.

Conclusion: In adults with functional constipation, the intake of a prebiotic formulation was associated with a decline of species richness and Shannon diversity. Further research regarding the associations between prebiotics and the composition and function of the gut microbiota is warranted.

Keywords: Functional constipation; Functional diversity; Functional richness; Gut microbiota; LMER models; Prebiotics; RCT; Shannon diversity; Species richness.