Characterization of the gut microbiota in older adults with vascular stiffness

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Vascular stiffness is a hallmark of vascular aging and a major risk factor for cardiovascular diseases in older adults. Emerging evidence suggests that gut microbiota dysbiosis may contribute to vascular dysfunction; however, the microbial characteristics associated with vascular stiffness remain insufficiently understood. This cross-sectional study included older adults with and without vascular stiffness. A total of 110 adults aged ≥ 60 years were recruited from nursing homes and categorized into the vascular stiffness group (baPWV ≥ 1800 cm/s, VG, n = 91) and a non–vascular stiffness group (baPWV < 1800 cm/s, CG, n = 19). Fecal samples were analyzed using shotgun metagenomic sequencing on the BGI DNBSEQ platform. Microbial composition, α-diversity, and functional profiles were characterized, and differential taxa and their associations with vascular stiffness-related parameters were evaluated. VG exhibited significantly higher abundances of Deltaproteobacteria , Desulfovibrionales , Rikenellaceae , Desulfovibrionaceae , and the genera Alistipes , Ruthenibacterium , and Eisenbergiella ( P < 0.05). In contrast, Holdemanella biformis and Veillonella tobetsuensis were enriched in CG (LDA score > 2). Functional pathway analysis revealed significant upregulation of lipid metabolism and betalain biosynthesis pathways in VG. Correlation analysis showed that Alistipes putredinis was positively associated with SBP, whereas Veillonella tobetsuensis was negatively associated with baPWV ( P < 0.05). Older adults with vascular stiffness exhibited distinct alterations in gut microbiota composition and functional profiles compared with non-affected controls. Although several microbial taxa were differentially abundant between groups, these associations were attenuated after adjustment for age, sex, and lipid profiles, suggesting that individual microbial taxa may be influenced by host aging and metabolic status. These findings indicate that vascular stiffness-associated gut microbiota alterations are more likely to reflect broader changes in microbial community structure and function rather than the independent effects of specific microbial taxa (Ethics committee: 2020082 H).