Mechanism and potential of vitamin C supplementation in sarcopenia prevention and treatment / 中国组织工程研究

ABSTRACT

BACKGROUND:Vitamin C,as an essential nutrient,has a wide range of biological effects and a variety of biological functions related to the pathogenesis of sarcopenia.Vitamin C supplementation is expected to be a novel prevention and treatment measure for sarcopenia. OBJECTIVE:To review recent research advances in the application of vitamin C in the pathogenesis and treatment of sarcopenia,and to discuss the potential role of vitamin C in the prevention and treatment of sarcopenia and possible mechanistic pathways based on published evidence. METHODS:The first author performed a computer search of PubMed,Web of Science,CNKI and other databases for relevant studies involving vitamin C in sarcopenia.The search keywords were"vitamin C,ascorbic acid,L-ascorbic acid,ascorbate,antioxidants,oxidative stress,sarcopenia,muscular atrophy,muscle weakness,muscle development,skeletal muscle regenerate,muscles,skeletal muscle"in English and Chinese,respectively.The search period was from each database inception to July 2023.After screening,85 articles were included for further review. RESULTS AND CONCLUSION:Ensuring adequate dietary vitamin C intake or maintaining normal circulating levels of vitamin C will help to reduce age-related muscle loss and decrease the prevalence of sarcopenia.In addition,vitamin C supplementation is also useful for improving skeletal muscle mass,strength and physical function with potential synergistic effects in exercise strategies for sarcopenia.The effects of vitamin C on sarcopenia may be via the following biological mechanisms:vitamin C limits the activation of the ubiquitin-proteasome pathway mainly by inhibiting oxidative stress and inflammatory responses in skeletal muscle,thus positively regulating protein metabolic homeostasis,and may enhance mitochondrial antioxidant defenses through its antioxidant effects to maintain healthy mitochondrial function.In addition,vitamin C affects myoblast proliferation,differentiation and myotube size,mainly by increasing the expression of myogenic regulatory factors and activating protein synthesis signaling pathways,which contribute to the promotion of muscle development as well as the repair and regeneration of damaged muscle tissue.The positive effects of vitamin C in sarcopenia need to be studied in large samples and with optimized designs for important influencing factors,such as the choice of supplementation dose and duration,the design of exercise prescription when vitamin C is combined with an exercise intervention,and the assessment of the redox status of the individual.It is recommended that future studies should be conducted in older patients with sarcopenia(<50 μmol/L)with suboptimal vitamin C status to investigate the efficacy of a combined intervention of long-term supplementation with 1 000 mg/d vitamin C(for 6 months or longer)with at least two or more types of multi-type combined exercise,with supplementation timed to take place at 1 hour after the end of the exercise,and with monitoring of markers of oxidative damage produced during the exercise such as malondialdehyde or protein hydroxyl levels were monitored.In conclusion,the optimal dose and timing of vitamin C supplementation for older adults with sarcopenia needs to be explored more,while the appropriate design of exercise prescriptions(especially the type and intensity of exercise)needs to be further determined.