Tannin-based supplementation influences gut microbiota composition and activity in IBS-D patients with a potential...

As the involvement of the intestinal microbiota in the etiopathology of irritable bowel syndrome, subtype diarrhoea (IBS-D) is now increasingly recognised, a preliminary, quasi-experimental, before-after and prospective study was conducted on 28 patients to test the effect of a tannin-based supplement on the composition and activity of the microbiota, after 8 weeks of treatment. No statistically significant differences were found in α- or β-diversity. However, sparse Partial Least Squares Discriminant Analysis (sPLS-DA) and Boruta algorithm did reveal significant changes in the relative abundance of specific groups of bacteria, highlighting the involvement of recognized of IBS-D biomarkes, namely Blautia (adj p = 3.5 × 10^-11), Eubacterium hallii group (adj p = 5.1 × 10^-12) and Dorea (adj p = 1.8 × 10^-18), which resulted significantly depleted by the treatment. The modulation of the composition of the gut microbiota had an impact also in the production of short chain fatty acids (SCFAs), which were modulated: acetate and butyrate (n.s. and p = 0.000143) increased while propionate and formate resulted to be significantly reduced (p = 0.00476 and p = 0.00011, respectively), following the supplementation. Finally, the sPLS analysis showed that the strongest association between faecal microbiome composition and clinical symptoms of IBS-D was given by Catenibacterium, which showed a positive correlation with evacuation-related symptoms. Such preliminary findings suggest that tannin supplementation could play an outstanding role in microbiota modulation in IBS-D patients, potentially improving their symptomatology, by selectively acting on the growth and the activity of specific groups of taxa.