Sex-specific differences in salivary microbiota composition and their associations with metabolic health in adults with excess body weight: a secondary cross-sectional analysis

Growing evidence links the oral microbiome to obesity-related outcomes, yet the influence of sex-related biological differences on salivary microbial profiles remains insufficiently explored. This exploratory study aimed to characterize the composition, abundance, and diversity of the salivary microbiota in Brazilian men and women with excess body weight and to examine its associations with cardiometabolic markers. This cross-sectional secondary analysis of a randomized controlled trial (REBEC: RBR-9832wsx) included 59 adults with excess body weight. Salivary microbiota was profiled through amplification of the 16 S rRNA V4 region, and bioinformatics analyses were performed using the Microbiome Analyst (v2.0). Associations between microbial taxa and clinical variables were assessed using Spearman’s correlation. Men exhibited greater alpha diversity at the family level by higher Shannon (p = 0.015, rrb = 0.4) and Simpson (p = 0.003, rrb = 0.5) indices. Sex-specific microbial differences were identified: men showed higher levels of genera Tannerella, Lachnoanaerobaculum, and Actinomyces, as well as the putative species-level taxons Tannerella serpentiformis and Lachnoanaerobaculum umeaense, whereas women demonstrated greater abundance of genera Campylobacter, Granulicatella, Moryella, and Scardovia. Among women, Granulicatella genera was positively associated with triglycerides and the TyG index. Men and women with excess body weight exhibited distinct salivary microbiota profiles, with differences in both diversity and taxonomic composition. Sex-specific differences in salivary microbiota composition may be associated with variations in metabolic markers. These findings are exploratory and hypothesis-generating, providing insight into sex-related patterns in the oral microbiome and may help inform future research exploring personalized approaches to cardiometabolic risk assessment.