Flexibility of Gut Microbiota in Ageing Individuals during Dietary Fiber Long‐Chain Inulin Intake

SCOPE: During ageing, dysbiosis in the intestinal microbiota may occur and impact health. There is a paucity of studies on the effect of fiber on the elderly microbiota and the flexibility of the aged microbiota upon prebiotic intake. It is hypothesized that chicory long‐chain inulin consumption can change microbiota composition, microbial fermentation products, and immunity in the elderly. METHODS AND RESULTS: A double‐blind, placebo‐controlled trial is performed in healthy individuals (55–80 years), in which microbiota composition is studied before, during, and after two months of chicory long‐chain inulin consumption. Fecal short chain fatty acid concentrations, T cell subsets, and antibody responses against a Hepatitis B (HB) vaccine are measured as well. Inulin consumption modified the microbiota composition, as measured by 16S rRNA sequencing. Participants consuming inulin have higher microbial diversity and a relatively higher abundance of the Bifidobacterium genus, as well as Alistipes shahii, Anaerostipes hadrus, and Parabacteroides distasonis. While the immune responses remain unchanged, the isobutyric acid levels, an undesired fermentation product, tend to be lower in the inulin group. CONCLUSIONS: Overall, it is shown that the gut microbiota composition is still sensitive to chicory long‐chain inulin induced changes in an ageing population, although this did not translate into an improved immune response to an HB vaccine.