Inulin changes three gut bacteria in constipated adults
What it found
In a 4-week trial in people with mild constipation, inulin increased Bifidobacterium and Anaerostipes and decreased Bilophila in the gut.
The drop in Bilophila was linked to softer stools and better quality of life.
What they found
Studies in people
Gut bacteria changes
Inulin increased the relative abundance of Bifidobacterium and Anaerostipes, and decreased Bilophila. No other consistent changes were found among the bacteria tested.
Metabolite changes
Only one faecal metabolite, dodecanal, increased with inulin. Other metabolite profiles did not change significantly.
Bilophila and symptoms
The decrease in Bilophila was linked to softer stools and improved scores on constipation-related quality of life, such as less physical discomfort and better treatment satisfaction.
Microbiome diversity
Inulin slightly reduced the richness of the gut bacteria, but this was not linked to stool consistency or frequency. No changes in overall diversity or enterotype distribution were seen.
What the authors conclude
“Ecosystem-wide analysis of the effect of a dietary intervention with prebiotic inulin-type fructans on the colon microbiota revealed that this effect is specifically associated with three genera, one of which ( Bilophila ) representing a promising novel target for mechanistic research.”
Also in their conclusions
- They conclude that inulin-type fructans selectively influence a limited number of colon bacteria, meeting the selectivity criterion for prebiotics.
- They state that the reduction of Bilophila, a genus containing known pathobionts, is associated with enhanced host well-being and could play a role in the prebiotic mechanism.
- They suggest that Bilophila represents a promising novel target for mechanistic research.
How it was done
The authors wanted to test whether prebiotics like inulin really act selectively on gut bacteria, since recent mice studies suggested broad effects. They also aimed to characterise the full impact of inulin on the gut ecosystem.
They analysed faecal samples from a double-blind, randomised, cross-over trial where 42 healthy adults with mild constipation took 12 g of chicory inulin or a placebo daily for 4 weeks each. They used gene sequencing and metabolite analysis to see how inulin affected gut bacteria and faecal compounds.
What it can’t tell you
- The study was in healthy, mildly constipated adults, so the results may not apply to other groups, such as people with obesity or different gut conditions.
- The analyses focused on volatile metabolites and did not cover all metabolites, so changes in other compounds may have been missed.
- The link between Bilophila and quality of life is an association, so it cannot prove that the bacterial change directly caused the improvement.
Who paid
- Funding
- Funded by Medical Research Council (from the PubMed record).
- Conflicts
- Competing interests: MS and ST are employees of BENEO/Südzucker Group. The authors alone are responsible for the content and writing of this article.
- Authors work at
- KU Leuven - University of Leuven, Belgium; Center for Microbiology, Belgium; Vrije Universiteit Brussel, Belgium
The paper
- Title
- Prebiotic inulin-type fructans induce specific changes in the human gut microbiota
- Type
- Randomised controlled trial
- Evidence
- Studies in people
- Summarised from
- Full text
- Cite
- Vandeputte D, Falony G, Vieira-Silva S, et al (2017). Prebiotic inulin-type fructans induce specific changes in the human gut microbiota. Gut. doi:10.1136/gutjnl-2016-313271Free full textPubMed 28213610DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error