Anti-aging treatments have always been popular, and their trendiness is not going away any time soon. Thanks to social media, more diets, procedures, and supplements promising to slow the aging process have been shared and sold, with thousands of social media users dishing on whether or not these treatments actually work to reduce the look (and feel) of natural aging. While medical research has begun to take a closer look at supplements, most specifically NMN and NAD+ supplements, it’s unclear whether they are the true “anti-aging miracles” everyone claims. This makes us wonder: what is an NMN supplement, and what does it exactly do?

NMN—short for nicotinamide mononucleotide or beta-nicotinamide mononucleotide—is one of the main precursors to NAD+, an essential enzyme partly responsible for DNA repair, cell growth and survival, and metabolism. Anecdotally, it works to slow aging, but what does the science say? We tapped a longevity doctor and registered dietitian to learn more about this popular, yet controversial supplement.

What is NMN?

NMN is a natural compound that helps the body produce NAD+, an enzyme responsible for cellular processes that produce energy. NAD+ occurs naturally in our body’s cells, but its production decreases as we age¹. Studies have shown this decline is linked with hallmark traits of aging, such as muscle loss, cognitive decline, inflammation, and fatigue.

While several other substances serve as precursors to NAD+ production, including NR (nicotinamide riboside¹⁴²), NA (nicotinic acid), and NAM (nicotinamide), NMN has become most popular because it’s thought to be highly effective at raising NAD+ levels and in theory, has more potent anti-aging benefits.

“NMN is known for its rapid absorption and efficient conversion to NAD+³, making it a preferred choice to boost NAD+ levels. However, its current regulatory status as a drug versus supplement is not clear,” Anurag Singh, MD, longevity expert and chief medical officer at Timeline Nutrition, tells Well+Good. (More on this in a bit.)

You can find NMN supplements sold in powder or capsule form and sometimes combined with other supposed anti-aging ingredients such as resveratrol—a polyphenol antioxidant found in grapes and berries that may enhance NAD+ production 60 to 70 percent⁴ more than NMN alone. Certain foods, such as edamame, cabbage, cucumber, broccoli, and avocado, also contain small amounts of NMN. However, most NMN supplements are produced synthetically.

What are the potential benefits of NMN?

Companies that make NMN supplements claim it enhances energy levels, strength and endurance, DNA repair, insulin sensitivity (the body’s ability to use insulin effectively), and brain health. While many of these benefits have been demonstrated in scientific studies involving mice, few of them have been demonstrated in studies with humans.

One human clinical trial from 2021 found that NMN supplementation was linked to an improvement in insulin sensitivity⁵ in middle-aged and older adults with prediabetes, while another study from 2020 found that NAD+ was associated with higher energy levels⁶ and increased sensitivity to insulin. (For context, our body’s ability to use insulin effectively deteriorates with age⁷, which can result in a higher risk of developing diabetes if left unchecked.) However, these studies were small, and the former only involved people with prediabetes, meaning we don’t know how effective NMN is for people without diabetes. We also don’t know how NMN will work for people of different ages and health statuses.

Another handful of small clinical trials found that NMN supplementation may be associated with enhanced muscular endurance⁸ and anaerobic capacity⁹—i.e., the body’s ability to produce energy while exercising—in trained runners. (Like insulin sensitivity, exercise capacity declines with age, so offsetting this could, in theory, help maintain mobility and independence as an older adult.) But again, these trials were small and would need to be replicated several times in various groups of people to confirm their results.

The bottom line? There is not enough research to definitively say NMN supplements can slow or reverse markers of aging. While trials are ongoing, and a handful of animal and human studies have delivered promising results, experts need more information to determine the efficacy of these supplements.

NMN side effects, risks, and dosage

Here’s a breakdown of some of the potential side effects and risks of NMN supplements—based on the research and knowledge we have of the supplement so far.

1. Long-term side effects are largely unknown

So far, clinical studies have found that NMN supplementation is generally safe and well-tolerated among healthy people. Most reported side effects are mild and can include things like headaches and nausea¹⁰. But, little is known about the long-term side effects of these supplements.

“Most of the research has been in animal models, and there is no long-term data on supplementation, though so far, studies seem to yield positive results,” says Stephanie Crabtree, a registered dietitian and owner of Holistic Health RD, LLC. That said, some animal studies have also raised concerns that large doses of NMN could promote inflammation¹¹ and toxicity symptoms like liver damage¹².

“NMN is less clinically studied in long-term studies in humans compared to other supplementation approaches, such as Urolithin A¹³ (a natural supplement produced by gut bacteria) and NR (nicotinamide riboside) that are alternative approaches to boost energy and mitochondrial health (i.e., the health of the mitochondria in your cells),” Dr. Singh adds.

2. Other active (and inactive) ingredients can cause side effects

Another thing to keep in mind? NMN supplements typically contain other active (and inactive) ingredients, which may cause certain side effects depending on the person. As we’ve learned, some capsules may have resveratrol, which can cause side effects like nausea, abdominal pain, and diarrhea. Others may also contain ingredients like berberine (a natural plant compound) and Reducose (a plant-based dietary supplement)—both of which are known for their blood-sugar-lowering effects.

3. Dosage varies depending on the person and their health

Because medical experts know very little about the long-term effects of NMN supplements, it’s best to chat with your healthcare provider first before trying them—especially if you have an underlying health condition or take certain prescription medications that could interact with the supplement. Even if you don’t fall into these categories, it’s best to check with your provider to see if NMN is right for you.

If your provider gives you the “okay” to try NMN, they’ll likely recommend starting at a low dose for a maximum of 12 weeks to possibly avoid any long-term effects. (So far, clinical trials have found that 250 to 1,200 milligrams per day¹⁵ for four to 12 weeks seems to be the “sweet spot” for potential benefits.)

4. It’s being investigated as a drug by the FDA

Turns out, there’s a bit of controversy surrounding NMN: In 2022, the Food and Drug Administration (FDA) banned NMN from being sold as a dietary supplement and began investigating the substance as a drug. This is because the claims made about the supplement’s benefits and efficacy more closely align with that of a medication rather than a supplement. Since then, organizations such as the Natural Products Association (NPA) and Alliance For Natural Health (ANH) have filed a citizen’s petition calling the FDA to re-evaluate NMN as a supplement instead because they believe NAD has potential life-extending benefits that should be available to more people.

Despite the regulatory murkiness, several companies continue to sell NMN (as evidenced by several TikTokers shelling products to viewers).

The final takeaway

NMN may be all over social media, with users claiming the supplement has helped them feel (and look) younger, but medical research is still limited and unclear as to whether it actually works to slow the signs of aging. While NMN supplements may boost natural NAD+ levels in our cells, their long-term side effects and impacts on the hallmarks of aging (like brain health and fatigue) are not completely understood or confirmed. More studies are also needed to determine whether NMN has any effect on health concerns like insulin sensitivity and exercise capacity.

Supplements and treatments aside, there are plenty of other lifestyle habits you can incorporate that help promote longevity and keep you healthy, such as eating a balanced diet while limiting ultra-processed foods, getting plenty of sleep, staying hydrated, exercising regularly, and reducing stress. Still, if you’re set on trying NMN supplements for the potential muscle endurance, insulin sensitivity, or general anti-aging effects, be sure to talk to your healthcare provider first to see if it’s right for you.