What is NMN, and Are There Any Side Effects? A Guide to NMN Supplements, Dosing, and Safety Research

Although the process of aging is undoubtedly complex, researchers in recent years have focused on how declining levels of NAD+ (nicotinamide adenine dinucleotide) play a significant role in our cells, organs, and bodies growing older. NAD+ is a vital coenzyme — a molecule that helps other enzymes function properly — needed by every cell in the body. However, by about age 60, our NAD+ levels drop by roughly half of what they once were. 

This decline in NAD+ levels increases the risk of accelerated aging and dysfunction in organs and cells. Keeping NAD+ levels elevated, especially in later life, is thought to slow down the aging process and keep us healthy with each passing year — from the inside out. 

One leading way to support NAD+ levels is through supplementing with its precursors, like NMN (nicotinamide mononucleotide). Although NMN supplements are becoming more and more popular in the anti-aging and longevity sphere, many people justifiably have questions about NMN: Are there NMN side effects? What is the ideal NMN dosage? And, what’s the latest evidence on NMN supplement research? Let’s take a closer look at these critical questions. 

The Basics of NMN and NAD+

One of the most well-known functions of NMN is its ability to be rapidly converted into NAD+. As a coenzyme, NAD+ helps other enzymes to function properly. NAD+ is involved in aiding processes ranging from brain cell growth to repairing DNA to helping our cells’ energy powerhouses, the mitochondria, generate energy from food. Essentially, NAD+ plays a critical role in maintaining cellular and metabolic functions, which translates to better health and longevity of our cells, organs, and bodies as a whole. 

So, where does NMN come in? Other than directly boosting levels of NAD+, NMN has also been studied for its effects on ameliorating various age-related conditions and improving markers of health and longevity. Scientists have looked at possible NMN side effects as well, noting its remarkable safety profile in trials. 

Some of the leading areas of recent research involving NMN include its link to supporting brain health and cognition, blood flow and vascular health, muscle strength and physical performance, and skin, eye, reproductive, and heart health. While most of these studies have been with animals or cell-based cultures, they are still a valuable stepping stone for supporting the use of NMN in humans.

Can NMN Extend Lifespan?

Many people also want to know if NMN or other NAD+ boosters extend lifespan. While we don’t have that data from human studies (which take multiple decades to complete), animal studies tend to be an adequate proxy. Even though humans aren’t mice or yeast or worms, these animals can serve as models for health and longevity research, as they have surprisingly similar anatomy and genetics as us — especially mice and rats.

Research has found that boosting NAD+ levels through precursors like NMN extends lifespan in these lesser species, including yeast and worms. For example, one 2013 study published in Cell found that both NMN and another NAD+ precursor, nicotinamide riboside (NR), extended the lifespan of the commonly studied lab worm, C. elegans, by over 10%. However, the research on NMN and lifespan in rodents and humans is still lacking. We will need additional studies before we can state definitively if NMN can lengthen lifespan in humans.   

Does NMN Work With Humans?

Some recent trials have tested NMN’s effects on human health — and with beneficial results so far. In one recent clinical study, postmenopausal women with poor blood glucose (sugar) control took 250 mg of NMN per day for ten weeks. The researchers found that NMN supplementation supported better blood sugar sensing in the skeletal muscle, which is linked to better metabolic health. 

Another aspect of physical health that can decline with age is our aerobic capacity — a measure of how well the cardiovascular system can deliver oxygen to muscles — with estimates of a 15% reduction per decade once we reach our 50s. Recent research out of Guangzhou Sport University in China provided the first-of-its-kind evidence that combining NMN with exercise supports aerobic function in humans. 

In this study authored by Liao and colleagues, healthy athletic adults took 300, 600, or 1200 mg of NMN daily for six weeks. The researchers found that ​​NMN boosted the aerobic capacity of humans in a dose-dependent manner. This means that more NMN produced a more significant effect. While the lower dose of NMN (300 mg/day) still exhibited aerobic-boosting benefits, they were about half that of the highest dose group (1200 mg/day). Although this study was done with young- to middle-aged adults, the results are promising for potentially translating to supporting older adults with diminished physical function. 

What Are the Side Effects and Safety of NMN?

NMN is generally considered a safe compound to take, as evidenced by a clinical study from 2020 that assessed the effects of a single dose of the NAD+ precursor in a group of ten adults. The researchers reported that a one-time administration of NMN, in doses ranging from 100 to 500 mg, was found to be safe and well-tolerated, causing no adverse NMN side effects. 

The researchers found no immediate or significant changes to sleep quality, eye function, heart rate, blood pressure, oxygen saturation, or body temperature. Overall, this study provided valuable information about the short-term safety and tolerability of NMN. However, more long-term research is warranted with varying ages, sexes, and ethnicities, as this sample size was small and included only healthy Japanese men between the ages of 40 and 60. 

Similarly, the other two previously mentioned human trials assessing NMN side effects in postmenopausal women and healthy athletic adults did not report any significant side effects. 

How to Take NMN Supplements and NMN Supplement Dosage 

With few human studies to go off of, the NMN doses that have been used in the available research in people range from 100 to 1200 mg per day. Hopefully, in the upcoming years, more research will better elucidate a smaller range of the ideal NMN dose to take. 

There are also several methods to take NMN, including powder, capsules, lozenges, and even through an IV drip. While one form isn’t necessarily better than another, they will have varying rates of absorption. An IV drip will be absorbed the fastest, as it bypasses the digestive tract and goes immediately into the bloodstream. Lozenges absorb more quickly than powders and capsules, with powders getting a bit of a jump start due to their lack of capsule casing. Both powders and capsules will first need to be broken down in some capacity by the stomach and intestines before reaching the bloodstream for utilization. 

Can NMN Reverse Aging?

The leading question that most people want to know about this NAD+ booster is, “Can NMN reverse aging?” The short answer is — we don’t know yet, but the available research is certainly encouraging. While supplemental NMN is linked to a reversal or delay of several age-related symptoms and conditions, we can’t say for sure if NMN reverses aging itself — especially in humans. 

Similarly, as the research on NMN and longevity is limited, we also can’t determine whether or not this NAD+ precursor extends lifespan. For now, there appear to be no significant NMN side effects and it appears to be a safe and well-tolerated compound with plenty of potential benefits to support a healthier aging process.

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References: 

Irie J, Inagaki E, Fujita M, et al. Effect of oral administration of nicotinamide mononucleotide on clinical parameters and nicotinamide metabolite levels in healthy Japanese men. Endocr J. 2020;67(2):153-160. doi:10.1507/endocrj.EJ19-0313

Liao B, Zhao Y, Wang D, Zhang X, Hao X, Hu M. Nicotinamide mononucleotide supplementation enhances aerobic capacity in amateur runners: a randomized, double-blind study. J Int Soc Sports Nutr. 2021;18(1):54.. doi:10.1186/s12970-021-00442-4

Mills KF, Yoshida S, Stein LR, et al. Long-Term Administration of Nicotinamide Mononucleotide Mitigates Age-Associated Physiological Decline in Mice. Cell Metab. 2016;24(6):795-806. doi:10.1016/j.cmet.2016.09.013

Mouchiroud L, Houtkooper RH, Moullan N, et al. The NAD(+)/Sirtuin Pathway Modulates Longevity through Activation of Mitochondrial UPR and FOXO Signaling. Cell. 2013;154(2):430-441. doi:10.1016/j.cell.2013.06.016

Yoshino M, Yoshino J, Kayser BD, et al. Nicotinamide mononucleotide increases muscle insulin sensitivity in prediabetic women. Science. 2021;eabe9985. doi:10.1126/science.abe9985