Japanese Traditional Kampo Medicine as a holistic countermeasure for spaceflight-induced physiological and psychological health challenges: a comprehensive review

Spaceflight introduces a complex array of health challenges that affect nearly every physiological system, primarily owing to microgravity, cosmic radiation, isolation, altered environments, and logistical supply constraints. Astronauts commonly experience musculoskeletal degradation, including bone density and muscle mass loss; cardiovascular deconditioning; and fluid redistribution. These lead to orthostatic intolerance; immune suppression; increased infection risk; exposure to ionizing radiation, which poses elevated risks of malignancy and neurodegenerative diseases; gastrointestinal dysfunction; gut dysbiosis; and cognitive, psychological, and sleep disturbances. These multifaceted stressors necessitate holistic and multitarget countermeasures, particularly as extended missions have become a reality. Japanese Traditional (Kampo) medicines, composed of multiple herbal ingredients, offer a promising supportive strategy because of their efficacy in simultaneously managing diverse physical and psychological symptoms. Kampo formulas exert diverse benefits. For example, Ninjin’yoeito, Juzentaihoto, Hochuekkito, and Goshajinkigan promote musculoskeletal strength and prevent frailty. Goreisan regulates fluid and cardiovascular homeostasis; Hochuekkito supports immune modulation and infection prevention; Rikkunshito address gastrointestinal symptoms via appetite and digestive regulation; and Yokukansan and Kamikihito mitigate neurological and psychological disturbances. Another benefit is the regulation of the gut microbiota, mitochondrial function, and gene expression, which are relevant to space-induced metabolic and inflammatory alterations. The holistic, preventive, and safe profile of Kampo medicines make them well suited for integrated health management in space, facilitating the maintenance of performance and quality of life during long-duration missions. Ongoing research and advances in personalized medicine will help clarify and optimize the application of Kampo in space medicine.