Age-associated arterial dysfunction, Western diet, and aerobic exercise: Role of the gut microbiome

Existing evidence suggests a link between changes in the gut microbiome with aging and vascular dysfunction in certain populations; however, the precise nature of this relationship in healthy older adults remains inadequately explored. We investigated age-related differences in gut microbiome composition among healthy, community-dwelling young (20-28 years; n=16) and older (60-78 years; n=19) adults. Compared with young adults, older adults displayed changes in ß-diversity (P = 0.001) and reduced a-diversity (P < 0.01) independent of dietary composition, lower abundance of short-chain fatty acid (SCFA)-producing (P = 0.0082) and other anti-inflammatory bacterial groups (P < 0.0001), and greater pro-inflammatory taxa (P = 0.0005). These differences were associated with greater circulating lipopolysaccharides (LPS; P = 0.0021) and pro-inflammatory cytokines interleukin-6 (IL-6) and C-reactive protein (CRP). Gut microbiome composition (a/ß-diversity) was related to vascular function, including endothelium-dependent dilation (measured as flow-mediated dilation) and arterial stiffness (carotid-femoral pulse wave velocity) (with [Pr>ChiSq] < 0.02 for all four regressions).