Study Shows NMN Is Safe For Humans
Three years ago in Japan, the first human clinical study for NMN was announced to study if NMN is safe for human consumption. Everyone who studies and consumes the NMN supplement to boost NAD in their body was excited to finally learn if NMN supplementation conferred similar lifespan enhancing attributes to humans that many research studies showed that it did in mouse models.
I will examine the objectives of the Japanese NMN human trial and remark on the recently published results, which have been widely misunderstood. This study's conclusion was not that NMN was ineffective at boosting NAD levels in the research participants, thereby did not confer health and longevity benefits to them. This potential was not examined. Instead, what the study did examine and show is that NMN is safe for humans.
The Intention of the Japanese NMN Human Trail: "Is NMN Safe for Humans"?
In announcing the study, science and technology journal Nature made four noteworthy observations to underscore why the NMN human study would be conducted. 
(1) Of the various disease-mitigating life extension enhancing interventions, the most practical are NAD precursors. One big reason for this is that the vast amount of data accumulated over the last 16 years indicate that NAD, a coenzyme found in virtually all our cells and essential for life, makes sirtuins work better. Sirtuins are a family of proteins that researchers say can promote longevity if they're working effectively, which requires adequate levels of NAD to do. Unfortunately, NAD levels fall as we age.
(2) NAD itself is difficult to administer directly to humans, but its precursors - nicotinamide riboside (NR) and nicotinamide mononucleotide (NMN) - are promising natural compounds with which to augment NAD levels in the cells and the body. The idea then is, take NMN or NR to boost NAD, which then makes the sirtuins do a better job of keeping you healthy and long-lived. 
(3) Both NR and NMN have been shown to be beneficial to ameliorate complications in glucose metabolism, cardiovascular and neural functions, and stem cell maintenance -- and even promote longevity in some studies, mainly of mice. 
(4) For NR, several clinical studies have already been ongoing in the US and Europe, and one human trial showed that NR does boost people's level of NAD. In the case of NMN, although it is already available on the market, the safety and effect on human physiology remain unknown.
Those observations were made in 2016 and were among the reasons cited to conduct the first NMN human trial. Those of us who follow longevity science waited with bated breath for the results. We would finally know if all those age-defying wonders conferred to mice by NMN would actually work for people as well.
What The Japanese NMN Human Study Did and Did Not Show
Those four points made above is the basic reason why the study of NMN on humans was conceived. About three years later on November 2, 2019 the results were released and reported on by Endocrine Journal; they were underwhelming, because NMN users expected more.
Unlike expectations, the study only evaluated whether NMN is safe for humans, not its effectiveness at boosting NAD to the extent necessary to have a favorable impact on sirtuins (the so-called "longevity genes"), and thus improve the health and longevity outcomes in people.
The study was done on only ten healthy men, ages 40 to 60. They were given a single oral administration of 100, 250, and 500 mgs of NMN. The men were then evaluated to see how those dosages of NMN affected various health parameters.
The researchers found that no single oral administration of NMN caused any significant clinical symptoms or changes in heart rate, blood pressure, oxygen saturation, or body temperature, but there are at least three notable points to consider about the NMN human study:
All NMN doses studied were fairly low. Even the highest dose of 500 mg is half of what numerous researchers and experts take, and advise for their clients. No animal studies showed the health and longevity benefits of NMN tested with just a single dose, but rather administered NMN daily for months.
NMN is safe and well tolerated; to that end, the human trial can be considered a success.
- Researchers now need to investigate the efficacy of NMN on humans, and a suitable dosage would then be established as part of that process. Fortunately, this is already underway with two studies, one being conducted by: the Brigham Health Institute study and the other by the Washington University School of Medicine. Hopefully, as anticipated, these studies will show if NMN boosts NAD in humans, and has an effect on biomarkers associated with health longevity.
Remember these three things:
- NMN supplementation has been routinely demonstrated to make mice biologically younger, and those outcomes have influenced thousands of people who supplement with NMN, including some researchers who study it.
- The only published human NMN study to date did not test its effectiveness at improving health and longevity outcomes of those studied, but did find that NMN is safe to take as a supplement.
- Two human NMN studies are now underway and they are expected to test to see if NMN supplementation it effective at improving the health and longevity of people.