Kampo medicine as a nutrition-relevant multi-target intervention for sarcopenia: implications for appetite, mitochondrial function, and the frailty-sarcopenia-cachexia continuum.

Background: Sarcopenia is sustained not only by age-related declines in muscle anabolism but also by reduced nutritional intake, anorexia, metabolic dysregulation, mitochondrial dysfunction, chronic inflammation, neuromuscular deterioration, and physical inactivity. Accordingly, interventions that influence appetite, oral intake, nutrient handling, fatigue, metabolic resilience, and physical function may be relevant within multimodal sarcopenia care. Kampo medicine, a traditional Japanese system of standardized multi-component herbal formulations, may be positioned as a nutrition-relevant multi-target intervention; however, its clinical evidence base for sarcopenia remains heterogeneous and largely indirect. Methods: We conducted a narrative review of published clinical, translational, and mechanistic literature addressing sarcopenia, frailty, cachexia, nutrition-related muscle wasting, the gut-muscle axis, systems pharmacology, and representative pharmaceutical-grade Kampo formulations. Searches were performed in PubMed, Scopus, and Web of Science from database inception to May 2026 using prespecified combinations of disease-, mechanism-, and formula-specific terms, supplemented by an additional search for Juzentaihoto/Juzen-taiho-to and related transliterations in response to peer review. Evidence was interpreted according to whether it directly evaluated sarcopenia outcomes or indirectly addressed nutrition-relevant domains such as appetite, fatigue, inflammation, mitochondrial function, physical activity, or neuromuscular symptoms. Results: Sarcopenia shares important pathophysiological features with frailty and cachexia, including chronic inflammation, impaired mitochondrial function, anabolic resistance, reduced food intake, fatigue, and neuromuscular dysfunction. Several Kampo formulations, including Ninjin'yoeito, Rikkunshito, Hochuekkito, Juzentaihoto, Hachimijiogan, and Goshajinkigan, have been associated with biological or clinical domains potentially relevant to appetite regulation, oral intake, inflammatory balance, gut microbiota-related pathways, metabolic resilience, and functional support. Nevertheless, direct evidence using standardized sarcopenia criteria and validated endpoints remains limited. Conclusion: Kampo medicine is best regarded as a hypothesis-generating, nutrition-relevant complementary approach within multimodal sarcopenia care rather than as an established stand-alone therapy for muscle loss. Future studies should use standardized diagnostic criteria, prespecified sarcopenia endpoints, rigorous safety monitoring, and transparent reporting to determine whether selected Kampo formulations can improve clinically meaningful nutrition-related and muscle-related outcomes.