as a Potential Nutrition-Responsive Biomarker for the Prevention of Age-Related Sarcopenia.

Sarcopenia, the age-related decline in skeletal muscle mass and function, is a growing health concern in aging populations. Nutritional interventions are increasingly recognized for their therapeutic potential; however, molecular biomarkers that reflect their efficacy are limited. To identify nutrition-responsive genes relevant to sarcopenia, we performed transcriptomic profiling of gastrocnemius muscle from mature and middle-aged mice. Aging-associated differentially expressed genes (DEGs) were filtered based on expression levels and correlation with muscle mass. Functional food interventions, including high- and low-molecular-weight collagen hydrolysates and allulose, were applied, and effect scores were calculated to assess transcriptomic responsiveness. Ajuba, a gene involved in cytoskeletal regulation and tissue remodeling, was significantly downregulated in middle-aged mice, consistent with aging-associated muscle decline. Dietary supplementation restored Ajuba expression across all intervention groups, with the strongest effect observed in the high-molecular-weight collagen group. Ajuba expression also showed strong positive correlations with tibialis anterior mass, hindlimb thickness, and muscle-to-fat ratio. Ajuba was identified as a nutritionally modifiable gene with strong associations to muscle phenotype and dietary response. These findings support Ajuba as a transcriptomic biomarker and potential molecular target for precision nutrition strategies aimed at preventing or mitigating sarcopenia.