As the elderly population rapidly increases worldwide, sarcopenia, the loss of muscle mass and strength due to aging, has become a growing global issue with significant impact on elderly health. In 2016, the World Health Organization (WHO) assigned a disease code (M63.84) to sarcopenia, highlighting the need for treatment development. Probiotics, live microorganisms beneficial to health, have recently been explored as potential treatments, but may cause adverse effects in immunocompromised individuals. This study investigates postbiotics—non-living bacterial products or metabolites—as a safer alternative with immune-modulatory, antioxidant, and lipid metabolism-regulating effects.

Animal experiments were conducted on 6-week-old male SD-rats to assess muscle mass and strength. Postbiotics MPG-1 prevented the loss of muscle mass and alleviated muscle strength reduction caused by dexamethasone. Molecular analysis revealed that postbiotics MPG-1 decreased the expression of Atrogin-1 and MuRF1, proteins involved in muscle protein degradation in the PI3K/AKT pathway, and reduced FoxO3a expression, a transcription factor that promotes autophagy. Additionally, AKT phosphorylation levels increased with postbiotics MPG-1 treatment. Further histological analyses and long-term studies are needed to confirm the link between these molecular changes and muscle fiber structure. This research provides valuable insights for sarcopenia treatment strategies.