NMN Supplements: Benefits, Side Effects, and More

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What Is NMN?​

Nicotinamide mononucleotide (NMN) is a molecule found naturally in our bodies and various foods.

It’s a “precursor” to nicotinamide adenine dinucleotide (NAD+), a vital coenzyme for health that plays a role in cellular processes, such as energy metabolism, DNA repair, and gene expression.

Levels of NAD+ typically decline as we age, prompting scientists to explore the effects of NMN on increasing NAD+ levels.

By replenishing the dwindling NAD+ reserves in older people, some researchers believe NMN could support healthy aging and combat age-related diseases, such as metabolic disease, cancer, frailty, and neurodegenerative diseases like Alzheimer’s disease.

What Is An NMN Supplement?​

NMN supplements are dietary supplements containing NMN powder, typically in doses ranging between 250 mg and 1,200 mg per serving.

The popularity of NMN supplements has surged in recent years, likely because several prominent figures in the health and wellness space, such as David Sinclair and Andrew Huberman, endorse them.

However, in late 2022, the FDA declared that because pharmaceutical companies are investigating NMN as a potential drug, supplement companies can no longer market it as a dietary supplement.

Metro International Biotech is one of the notable pharmaceutical firms studying NMN that lobbied for the ban. It’s pertinent because Davis Sinclair is one of its co-founders.

His alleged involvement in the FDA ban has led some to accuse Sinclair of boosting the demand for NMN by championing the molecule while trying to control its supply by limiting its sale. Sinclair denies these claims.

Nevertheless, the FDA isn’t actively enforcing the ban, and NMN supplements are still widely available online.

NNM Supplement Benefits​

According to NMN supplement manufacturers, NMN benefits your health in numerous ways.

The most commonly claimed NMN benefits include:

• Improved cardiometabolic health
• Increased physical activity and skeletal muscle capacity
• Improved cognitive function

Let’s look closer at the research on NMN to see which of these claims are valid.

Cardiometabolic Health​

Animal research investigating how NMN affects cardiometabolic health is positive.

Studies published in the journals Aging Cell and Cell found NMN restored NAD+ levels in older mice, enhancing cardiovascular health and reversing age-related reductions in blood flow and capillary density.

Scientists at Washington University School of Medicine found that NMN replenished NAD+ levels in diabetic mice, which improved the rodents’ insulin sensitivity and blood lipid profile and restored gene expression related to circadian rhythm, inflammation, and oxidative stress.

Human research is less optimistic.

In a 2021 study published in Science, researchers gave postmenopausal women with prediabetes 250 mg of NMN or a placebo daily for 10 weeks.

The results showed that while taking NMN caused blood NAD+ levels to rise, muscle NAD+ levels remained the same, a finding echoed in research on an almost identical molecule called nicotinamide riboside (NR).

In other words, the body doesn’t absorb NMN into skeletal muscle, potentially limiting its benefit.

Furthermore, the women didn’t experience changes in body composition, blood glucose and insulin levels, or blood pressure, though they did see a 25% increase in their muscle insulin sensitivity.

In another study published in Scientific Reports, researchers found no improvement in arterial health among healthy middle-aged people who took NMN for 12 weeks.

Studies published in Scientific Reports and Clinical Nutrition ESPEN also found taking NMN failed to improve blood levels of glucose, insulin, and cholesterol. In fact, NMN increased blood insulin levels after eating in the latter, which could have negative health consequences.

At bottom, there’s little compelling evidence that NMN benefits cardiometabolic health.

Physical Performance and Body Composition​

In a study by scientists at Guangzhou Sport University, runners taking 300-to-1,200 mg of NMN daily failed to improve several markers of physical performance or cardiovascular fitness after 6 weeks.

They also experienced no change in body weight, muscle mass, BMI, or body fat percentage and didn’t perform better in grip strength, push-up, or “sit and reach” tests than the placebo group.

Similarly, studies by Effepharm (Shanghai) Co., Ltd., Osaka University Graduate School of Medicine, and the University of Tsukuba found that while taking NMN supplements raised blood NAD+ levels, it didn’t have a significant effect on walking endurance and speed or grip strength.

These clinical trials also found that taking NMN didn’t significantly enhance insulin sensitivity, general well-being, sleep quality, or fatigue.

Two studies suggest NMN may benefit physical performance.

The first was published in NPJ Aging and found that taking NMN “nominally” increased walking speed and grip strength but had no effect on body composition, hearing, blood pressure, vascular health, or cognitive function.

Meanwhile, the second, published in GeroScience, found that taking NMN “halted” aging (according to an AI-driven blood test) and boosted walking performance.

While these results seem striking, most experts doubt their authenticity, primarily because the study was short, the AI’s accuracy and study methodology were dubious, and a supplement company with a vested interest in the results funded and conducted the research.

There were also a couple of anomalies in the data that added a layer of peculiarity. For instance, even though the study only lasted 60 days, the AI predicted the participants in the placebo group had aged more than 5 years. Furthermore, the study’s participants walked suspiciously slow for healthy 50-year-olds—some trudged just over 300 meters in 6 minutes.

Ultimately, there’s scant scientific evidence that NMN improves physical performance or body composition.

Cognitive Function​

Clinical trials published in NPJ Aging and Mechanisms of Disease, Neuroscience, Redox Biology, and Brain Research show that taking NMN improves cognitive function in older animals.

Research is yet to uncover similar results in humans.

Other Potential Benefits​

Several studies show that mice taking NMN are more protected from DNA damage and have better reproductive, bone, kidney, and eye health.

Scientists are yet to replicate these findings in humans.

NMN Supplement Side Effects​

Most human research shows there are very few NMN side effects. It’s well-tolerated and causes no adverse effects, even with long-term use.

That said, it’s difficult to know how trustworthy NMN supplements are.

A supplement manufacturer independently analyzed the 22 most popular NMN brands on Amazon. They tested the brands’ NMN supplements for potency and found the following:

• 14% met or exceeded the NMN amount on the label.
• 23% fell slightly short of the label’s claim (they contained 88-to-99% of the stated amount).
• 64% contained less than 1% of the amount of NMN claimed on the label.
• 14% contained no NMN.

In other words, even the most popular NMN supplements have wildly inaccurate labels.

And while none of the supplements in this analysis contained dangerously large doses of NMN, there may be supplements out there that do.

If you’re considering using an NMN supplement, the best way to protect yourself is to only use supplements from a reputable brand that undergoes third-party testing for purity and potency.

Conclusion​

While some “experts” champion the benefits of NMN supplements, there’s little reason to think they impact longevity.

Does this mean your NAD+ levels are doomed to dwindle with age, cutting your life short?

Not at all.

Studies indicate that NAD+ mainly decreases in inactive individuals. Conversely, active older people maintain NAD+ levels comparable to younger folks. That is, regular exercise is key to optimizing NAD+ levels as you age.