Effects of Nicotinamide Mononucleotide Supplementation on Muscle and Liver Functions Among the Middle-aged and Elderly: A Systematic Review and Meta-analysis of Randomized Controlled Trials

INTRODUCTION: Nicotinamide Mononucleotide (NMN) has gained attention as a precursor to Nicotinamide Adenine Dinucleotide (NAD+) in recent years, commonly utilized in anti-aging therapies. The anti-aging effects of NMN on muscle and liver functions in middleaged and elderly people are still unclear. OBJECTIVE: Based on available randomized controlled trials, we conducted a meta-analysis to evaluate the impact of NMN on muscle and liver functions in middle-aged and elderly individuals. METHODS: We conducted searches on three electronic databases (PubMed, Embase, Web of Science) for randomized controlled trials involving NMN interventions in middle-aged and elderly populations. Through the Cochrane Handbook, we assessed the specific methodological quality. All statistical analyses were obtained by Stata15, and statistical significance was set as P<0.05. RESULTS: There were 412 participants from 9 studies in this meta-analysis. Based on changes in gait speed (SMD: 0.34 m/s, 95%CI [0.03, 0.66] p = 0.033), NMN had significant effects on muscle mass. Moreover, NMN had a better effect on ALT (SMD: -0.29 IU/L, 95%CI [-0.55, -0.03] p = 0.028). Subgroup analysis indicated that administering a small dose of NMN exerted the most prominent impact on Homeostasis Model Assessment-Insulin Resistance (HOMA-IR). CONCLUSION: NMN has positive efficacy in enhancing muscle function, reducing insulin resistance and lowering aminotransferase levels in middle-aged and elderly individuals. NMN is an encouraging and considerable drug for anti-aging treatment.