The average human lifespan worldwide has increased, leading to a massive increase in people with age-related diseases, such as cancer, cardiovascular disease, type 2 diabetes, high blood pressure (hypertension), and macular degeneration. In animal models, the administration of nicotinamide mononucleotide (NMN) has been shown to mitigate aging-related dysfunctions. However, the effectiveness, let alone safety, of NMN in humans has not been studied extensively.

For this reason, researchers from Keio University School of Medicine in Japan ran a clinical study to measure the safety and efficacy of NMN in humans. Irie and colleagues found that a single oral administration of NMN was safe and effectively metabolized in healthy men without causing any significant deleterious effects.

“In this study, we reported the safety of the single oral administration of NMN and the kinetics of NMN metabolites in healthy men,” stated Irie and colleagues.

NMN treats age-related dysfunction in animals

Recent studies have revealed that a decline in cellular nicotinamide adenine dinucleotide (NAD+) levels causes aging-related disorders and therapeutic approaches increasing cellular NAD+ prevent these disorders in animal models.

NMN, an NAD+ precursor, has certain advantages over other molecules that modulate NAD+. For example, although nicotinamide is obtained from a standard diet, when consumed in high quantities it induces nausea and flushing, which makes using nicotinamide as an NAD+ precursor difficult.

Also, we know that mammalian cells can directly absorb NMN. A recent report demonstrates that a transporter in the small intestine of rodents rapidly absorbs NMN, meaning NMN administration could improve NAD+ concentrations in cells.1

Numerous studies in animals provide evidence that NMN administration mitigates the age-related decline of the liver, adipose tissue, muscle, pancreas, kidney, retina, and central nervous system (brain and spinal cord). NMN administration has been shown to restore NAD+ tissue levels and improve symptoms from obesity, kidney failure (renal failure), and retinal degeneration in rodents.2,5,6,7

Although these studies in animals, also known as preclinical trials, provide evidence for NMN as an anti-aging intervention, the safety and efficacy of NMN in humans have been unclear.

Clinical trial tests NMN in humans

The Keio University School of Medicine research team tested the effect of oral administration of NMN in people. To do so, they provided 100, 200, and 500 mg NMN capsules to 10 healthy men.

These participants had to fast for one night prior to consuming the NMN capsules the following morning at 9:00 AM.  Following taking the oral doses of NMN, the men were only allowed to consume water for the ensuing five hours until they underwent physiological examinations.

The results show that the participants tolerated NMN well at each dosage. They didn’t present with gastrointestinal issues or changes to heart rate, blood pressure, oxygen saturation, or body temperature. When Irie and colleagues took a look at the neurological system, they couldn’t identify any significant changes following NMN consumption. There were no changes to the sleep quality of the participants.

Laboratory analysis of blood and urine indicate no changes before and after NMN consumption, except for blood bilirubin, creatinine, chloride, and glucose levels. Nevertheless, these changes were within normal ranges.

The evidence from the study indicates single, oral administration up to 500 mg is safe. “The oral administration of NMN was found to be feasible, implicating a potential therapeutic strategy to mitigate aging-related disorders in humans,” proposed Irie and colleagues.

Future NMN clinical studies

Since this study only examined the effect of a single dose of NMN, more studies are needed testing longer treatments with NMN. In addition, future studies should also include women to increase the power of the studies. These studies were performed in healthy individuals, so it will also be interesting to see whether NMN is safe and effective in people with age-related disorders.