The average human lifespan worldwide has increased.  With people living longer on average, prevention and treatment of age-related diseases continues to gain prevalence.  Aging is correlated with an increase in incidence of many diseases, including cancer, cardiovascular disease, type 2 diabetes, high blood pressure (hypertension), and macular degeneration.  Studies in animal models provide evidence NMN administration can mitigate age-related decline in liver, adipose tissue, muscle, pancreas, kidney, retina, and central nervous system.  Studies report NMN administration restores NAD+ tissue levels and improves symptoms from obesity, kidney failure (renal failure), and retinal degeneration in rodent models.2,5,6,7  A recent report demonstrates a transporter in the small intestine rapidly absorbs NMN, meaning NMN administration may provide a means for improving NAD+ concentrations in cells.1  Although preclinical trials provide evidence of NMN as an anti-aging intervention, safety and efficacy of NMN in humans remain ill defined.

For this reason, scientists from Keio University School of Medicine in Japan create a study to measure the safety and efficacy of NMN in humans.  This study presents the administration of 100, 200, and 500 mg NMN capsules in 10 healthy men.  Participating men fast for a night then consume NMN capsules the next morning at 9:00 AM.  The men only consume water for five hours after NMN administration.  After five hours, the scientists give the men physiological examinations.

The results indicate the men tolerate the NMN well at each dosage, with no problems such as gastrointestinal symptoms.  Regardless of dose, the NMN presents no effect on heart rate, blood pressure, oxygen saturation, or body temperature.  Examination of the neurological system, interior surface of the eye (ocular fundus), and visual system (ophthalmic system) indicate no significant changes following NMN consumption.  Sleep quality measurements do not differ before and after NMN administration.  Laboratory analysis of blood and urine indicate no changes before and after NMN consumption, except for blood bilirubin, creatinine, chloride, and glucose levels.  Levels of bilirubin increase 51.3%, while glucose, creatinine, and chloride decrease 11.7%, 5.1%, and 2.3%, respectively.  These changes remain within normal ranges.

NMN has advantages to other precursor NAD+ molecules, such as nicotinamide.  Nicotinamide is obtained from a standard diet and when consumed in high quantities induces nausea and flushing4, which makes using nicotinamide as a NAD+ precursor difficult.  Since NMN supplementation increases NAD+ levels in organs and improves symptoms of age-related diseases in aging mice,5,6,7 it is important to examine safety and efficacy of administering NMN.

The evidence from the study indicates single, oral administration up to 500 mg is safe and produces no gastrointestinal symptoms in healthy men.  Oral administration could provide a therapeutic strategy to replenish NAD+ levels to mitigate age-related disorders in humans.  Future studies should look at effects from long-term NMN administration as this study only examines effects of single doses of NMN.  Future studies should also include women to increase the power of the studies.