The Safety and Antiaging Effects of Nicotinamide Mononucleotide in Human Clinical Trials: an Update

This review summarizes laboratory evidence, published human NMN trials, and clinical-trial registries. Short human studies generally reported that oral NMN was tolerated and sometimes changed NAD-related biomarkers or selected functional outcomes. However, results were inconsistent and the trials were usually small and brief. The authors concluded that evidence for broad anti-aging effects remains scarce and that larger, longer, more diverse studies are needed.

The review identified 10 published human trials and described additional completed and ongoing registrations. Published studies generally reported short-term tolerability across varied oral doses and durations. Some trials reported increases in NAD-related metabolites or changes in selected metabolic, physical, sleep, fatigue, or telomere endpoints, while other outcomes were null. The authors emphasized that convincing human evidence for broad anti-aging effects is scarce and that no standardized normal NAD+ range or validated global anti-aging outcome exists.

This is a narrative review rather than a preregistered systematic review or meta-analysis. Search, selection, and synthesis methods do not provide the same protection against bias as a systematic review. The underlying trials were heterogeneous in population, dose, formulation, duration, and endpoints, and most were small and short. Some registered trials lacked published results, and long-term safety and clinically meaningful effects remain uncertain.