Association Between Gut Microbiota Composition and Carotid Atherosclerosis in Asymptomatic Individuals Undergoing Brain Health Screening

The gut microbiota has been implicated in cardiovascular disease, but its association with subclinical carotid atherosclerosis (AS) and potential sex differences remain incompletely understood. Associations between gut microbiota composition and subclinical carotid AS were investigated in 82 asymptomatic Japanese adults (39 men, 43 women) undergoing brain health screening. Carotid AS was defined as maximum intima–media thickness (IMT) ≥ 1.1 mm, and gut microbiota composition was assessed by 16S rRNA gene sequencing. Multivariable differential abundance analysis was performed using MaAsLin 3, adjusting for age, body mass index as appropriate, hypertension, diabetes mellitus, and dyslipidemia in sex-stratified analyses. Phascolarctobacterium and Turicibacter in men, and Megasphaera, Streptococcus, Allisonella, Bacillus, and Ruthenibacterium in women were identified as candidate taxa associated with carotid AS status. Integrated models combining clinical factors with these microbial signatures showed areas under the receiver operating characteristic curve of 0.79 in men and 0.95 in women. These findings suggest that gut microbial signatures associated with subclinical carotid AS differ by sex and may provide complementary information for characterizing early vascular changes. Larger prospective studies with independent validation are required to confirm these exploratory findings.