Xylo-oligosaccharides improve functional constipation by targeted enrichment of Bifidobacterium.

Functional constipation (FC) has a negative impact on patients' quality of life. We hypothesized that dietary supplementation with xylo-oligosaccharides (XOS) or fructo-oligosaccharides (FOS) would improve constipation symptoms by influencing the gut microbiota. A randomized double-blind controlled trial was conducted in FC patients. Patients were randomly divided into 6 groups and given a dietary supplement containing XOS at doses of 3, 5, or 10 g/day, FOS at doses of 10 and 20 g/day, or placebo at 5 g/day for one month. We compared improvements in gastrointestinal function after the intervention using the Bristol Stool Form Scale (BSFS), Cleveland Clinic Constipation Score (CCCS), and Quality of Life Scale for Patients with Constipation (PAC-QoL). 16S rRNA sequencing was used to assess changes in the structure of the gut microbiota. Changes in individual bacteria had significant effects in reducing gastrointestinal symptoms during the intervention, even though the flora structure remained unchanged from baseline. Compared to FOS, XOS enriched Bifidobacterium at a lower dose, and patients receiving XOS supplementation showed significant improvements in constipation symptoms without side effects such as diarrhea and flatulence.