Distinct gut microbiota signatures in older people with sarcopenic obesity and sarcopenia without obesity.

Previous evidence suggests that gut dysbiosis plays an important role in the development and progression of sarcopenia and sarcopenic obesity (SO), but evidence supporting this association is lacking. Thus, this study aimed to investigate the characteristics of gut microbiota in older people with sarcopenia and SO.

A total of 1558 older adults (age ≥65 years) from a community-based cohort in Shanghai, China, underwent sarcopenia screening using the SARC-F questionnaire, with 351 participants completing further assessment. On the basis of the Asian Working Group for Sarcopenia 2019 and the World Health Organization obesity criteria, 60 participants were categorized into three groups: SO (n = 20), sarcopenia without obesity (Sar, n = 18), and controls (Con, n = 22).

Gut microbiota composition was analyzed using 16S rRNA sequencing (V3-V4 regions). Significant differences in the diversity and composition of the gut microbiota were observed in the Sar and SO groups.

A reduction in alpha diversity (Chao1 and ACE indices) was found in the SO group. Beta diversity based on unweighted Unifrac PCoA was significantly different among the three groups.

LEfSe analysis identified 39 taxa with significant differential abundances across groups. The Sar group exhibited enrichment of Christensenellaceae_R-7_group, Alistipes, Ruminococcus, Odoribacter, Prevotellaceae_UCG-001, Hungatella, Family_XIII_AD3011_group, Anaerotruncus, Ruminiclostridium, and Oxalobacter, along with their high taxonomic classifications.

Meanwhile, Enterobacteriaceae, Allisonella, and Peptoclostridium were enriched in the SO group. Feature selection via Boruta algorithm identified five and four discriminatory taxa to construct random forest models, effectively distinguishing individuals with Sar and SO from Con.

Key predictors for Sar included reduced Enterococcus, Enterobacter, and Hungatella and increased Odoribacter and Christensenellaceae_R-7_group. Conversely, SO was characterized by decreased Enterobacter, Alloprevotella, and Enterococcus and increased Allisonella.

Five-fold cross-validation confirmed robust diagnostic efficacy, achieving AUCs of 0.860 (95 % CI: 0.786-0.996) for Sar and 0.826 (95 % CI: 0.735-0.970) for SO. This study demonstrated that the gut microbiota of SO and Sar have distinct diversity and composition profiles.

The results provide new insights into the role of gut microbiota in SO, highlighting its potential as a therapeutic target in this condition.