An exercise intervention alters stool microbiota and metabolites among older, sedentary adults

Abstract

Background: Physiologic aging has been associated with gut dysbiosis. Although short exercise interventions have been linked to beneficial changes in gut microbiota in younger adults, limited data are available from older populations. We hypothesized that exercise would produce beneficial shifts in microbiota and short-chain fatty acid (SCFA) levels in older persons.

Methods: Stool samples were collected before and at completion of a supervised 24-week cardiovascular and resistance exercise intervention among 50-75-year-old participants. SCFA levels were analyzed by gas chromatography and microbiome by 16S rRNA gene sequencing. Negative binomial regression models compared pre- and post-differences using false discovery rates for multiple comparison.

Results: A total of 22 participants provided pre-intervention samples; 15 provided samples at study completion. At baseline, the majority of participants were men (95%), mean age 58.0 (8.8) years, mean body mass index 27.4 (6.4) kg/m2. After 24 weeks of exercise, at the genus level, exercise was associated with significant increases in Bifidobacterium (and other unidentified genera within Bifidobacteriaceae), Oscillospira, Anaerostipes, and decreased Prevotella and Oribacterium (p < 0.001). Stool butyrate increased with exercise [5.44 (95% confidence interval 1.54, 9.24) mmol/g, p = 0.02], though no significant differences in acetate or propionate (p ⩾ 0.09) were seen.

Conclusion: Our pilot study suggested that an exercise intervention is associated with changes in the microbiome of older adults and a key bacterial metabolite, butyrate. Although some of these changes could potentially reverse age-related dysbiosis, future studies are required to determine the contribution of changes to the microbiome in the beneficial effect of exercise on overall health of older adults. Clinical Trials NCT02404792.

Keywords: aging; exercise; microbiome; physical function; stool metabolites.

Conflict of interest statement

Conflict of interest statement: KME has received research funding (to the University of Colorado) from Gilead Sciences, and consulting payments from Theratechnologies, Gilead Sciences, and ViiV Pharmaceuticals.

© The Author(s), 2021.

Figures

Figure 1.

Stacked bar charts representing mean RA at the (a) phylum, (b) family, and (c) genus levels in individuals with 16sRNA sequencing data pre- and post-exercise intervention (N = 15). Taxa with RA <2% were collapsed into a single category. PERMANOVA tests stratified by individual were conducted to test whether beta-diversity changed significantly from pre- to post-intervention. Acti, Actinobacteria; Bact, Bacteroidetes; Firm, Firmicutes; RA, relative abundance.

Figure 2.

Forest plot showing the estimate and 95% CIs for all genus level taxa where the exercise intervention had a significant effect on RA. Values are shown for unadjusted analyses (light blue dot) as well as estimates (95% CI) when adjusted for age (green dot) or exercise intensity (purple dot). Estimates above 1 suggest higher RA of genus taxa following exercise intervention with higher levels at older ages when adjusting for age and higher levels in the high-intensity group when adjusting for exercise intensity. Estimates below 1 indicate lower RA with lower levels at higher ages or in the high-intensity exercise group. ‘Other’ refers to all sequences that were classified to the taxa level detailed, but could not be further classified to specific genus. CI, confidence interval; FDR, false discovery rate; RA, relative abundance.