NMN vs. NAD

Probably everyone who has lived past 30 has reckoned with what it means to age. That’s typically when people begin to see firsthand evidence that aging isn’t just the passing of time but also the accumulation of mental and physical changes, big and small. Each age-related change you experience begins at the cellular level, and it can be addressed likewise.

In roughly the past 20 years, a coenzyme called nicotinamide adenine dinucleotide (NAD) has gained the spotlight as a linchpin in the cellular aging process. If you can maintain your stores of NAD as you grow older, you may be able to stave off some of those diseases we normally associate with senescence — heart disease, cancer, and neurodegeneration, for example.

The challenge is that NAD levels naturally decline over time, and maintenance isn’t a simple matter of taking an NAD pill. Instead, the most effective and accessible way to prevent NAD level decline is to exploit the biological processes that cause the body to make NAD in the first place. That is, you take an NAD precursor, like nicotinamide mononucleotide (NMN).

In this guide, we take you on a close-quarters tour through NAD and NMN, explaining what exactly they are, how they relate to each other, and why NMN is the superior supplement option between them. By the end, you ought to have the knowledge you need to make an informed health decision that may help you extend your lifespan while looking and feeling like a younger version of yourself.

As a supplement, NAD’s poor oral bioavailability means it will do little to increase your NAD+ levels.14 To get any significant effect from straight NAD administration, it would have to be delivered by IV infusion, which is very time-consuming and costly. NMN, on the other hand, has excellent oral bioavailability and easily converts to NAD+ inside your body. Furthermore, it may provide other health benefits on its own, with studies showing that it can suppress age-related weight gain, increase insulin sensitivity, and improve eye function. To learn more, visit our full guide to NMN supplements or learn more about our top recommendation below.

NAD refers to nicotinamide adenine dinucleotide. It’s an umbrella term for two coenzymes, or molecules that assist enzymes in carrying out their biochemical reactions. There’s NAD+, the oxidized form, and NADH (NAD with hydrogen), the reduced form. Both are essential to key biochemical processes, including glycolysis, by which cells produce energy. The science of oxidation and reduction (redox) reactions can be a lot to digest, but as it relates to NAD, we can simplify it like this:1

• NAD+ is an electron acceptor. It takes electrons and protons from hydrogen and becomes NADH.
• NADH is an electron donor. Once it enters mitochondria, it releases its electrons to fuel the electron transport chain, which itself fuels cellular energy production. Some NADH then converts back to NAD+.
• The cycle begins anew.

So, why is it that NAD+, and not NADH, is the star subject of recent longevity studies? Two reasons, mainly:

The sum of it is this: redox balance and healthy mitochondria help stave off the effects of aging, and you need sufficient stores of NAD+ to have both.

NAD+ occurs naturally in the body via three pathways, along with a cast of biological actors variably comprising:

Here’s a more detailed breakdown of how they play out in their respective roles:

Notice that catalyzing actors in the Preiss-Handler and de novo synthesis pathways — NA and tryptophan, respectively — both can cause undesirable effects on their own. NMN, one of the precursors in the salvage pathway, is less prone to causing such or similar risks.

Although your body produces NAD+ by multiple cyclical pathways, remember that NAD+ levels decline with age, and unless you restore your levels, you leave your mitochondria in a vulnerable state and your body more susceptible to the diseases we’ve mentioned.10

You have a few options for restoring your levels.

You could go to a clinic for an NAD+ infusion, in which a medical practitioner hooks you up to an IV drip that delivers the coenzyme directly into your bloodstream. This therapy can significantly increase your plasma NAD+ levels for a sustained period, but you have to be patient. You’ll need no less than two hours, with a needle in your arm to see the desired increases, and sessions can last even longer than that.11 They’re pricey, too, ranging from $250 to $1,500 per infusion, according to the Vaccine Alliance.12

NAD+ injections are a less time- and cost-intensive alternative. Rather than hours of IV infusion, you get a quick intramuscular stick with a needle syringe. This can be done at a clinic or at home; depending on which treatment pathway you choose, an injection can cost as little as $25 and as much as $200.12 But for all that, the effects aren’t all that long-lasting, so you may need to receive a fresh injection every 1-2 weeks, if not several times per week.13 The cost quickly adds up. Moreover, most of the supportive research for direct NAD+ administration to the blood has relied on infusion, so dose recommendations for injections are less clear.

The third option, an NAD+ boosting supplement, is the most economical, and therefore the most sustainable for the broadest population of people. The concern, though, is bioavailability. Taken orally, most of the NAD+ in a supplement will degrade in the digestive tract and ultimately fail to increase your levels.14 But the same cannot be said for NAD+ precursors. Both NMN and NR are absorbed well and quite rapidly through digestion, and either one would be a solid pick for an NAD+ boosting supplement.15

But if you had to pick just one, know that NMN boasts a few qualities, unreplicated thus far with other precursors, that might help you decide whether it’s better aligned with your health goals than NR.

Nicotinamide mononucleotide (NMN) is one of the main NAD+ precursors in the body. Most of our NMN is synthesized from a form of B3 called niacinamide (NAM).16 The conversion of NAM to NMN relies on a type of molecule called a methyl donor, of which your body has a finite “pool” from which to draw for diverse biochemical processes.17 From there, the NMN converts to NAD+.

As a supplement, NMN is much more orally bioavailable than NAD+.18 That, coupled with the fact that it’s just one step removed from becoming NAD+ in the salvage pathway — as opposed to NR, which must first be converted to NMN — means it’s theoretically the best choice for an NAD+ booster.

We referred earlier to the qualities of NMN that so far have yet to be replicated by other precursors, such as NR. Specifically, in clinical research, NMN has demonstrated the ability to suppress age-related weight gain, improve insulin sensitivity, and improve eye function, none of which NR has demonstrated to date.16 To be sure, NR is linked to a separate health benefit that NMN is not: specifically, it has been shown to decrease biomarkers of neurodegeneration by itself.19

Apart from the risk of an allergic reaction — which practically any supplemental, medical, or dietary substance can cause — NMN and NAD pose little to no danger in the short term.

With NAD, the most likely effects are mild. An oral NAD supplement, at high enough doses, might upset your stomach, give you gas, or make you feel bloated; and as an IV infusion or intramuscular injection, it might cause an injection site reaction, other local skin irritation, and significant nausea. In rare cases, high-dose NAD therapy may lead to kidney dysfunction or an electrolyte imbalance, typically when there’s a preexisting condition at play.20

As for NMN, oral supplementation has yielded no serious adverse events in clinical settings, even with doses up to 1,200mg per day.21 22 But we should reiterate that these are short-term findings. Over time, with consistent supplementation, NMN could theoretically give you cause for concern.

Theoretical health risks of NMN supplementation

The theoretical health risks in question are downstream effects related to the process by which your body makes NAD+. To recap:

• Via the salvage pathway, NAM is converted to NMN, and then NMN becomes NAD+.
• Methyl donors assist in this conversion.
• NAD+ allows your cells to function more efficiently.
• Leftover NAM is cycled back to the beginning of the pathway, and the cycle starts over.

The second and third points in the above process are of key concern, as they contribute to one of two potential adverse effects:

NMN’s legal status

NMN’s legal status isn’t exactly a safety issue, but it’s at least safety-adjacent and worth discussing here.

In 2022, the U.S. Food & Drug Administration (FDA) announced the prohibition of NMN for sale as a dietary supplement. This wasn’t due to any newly discovered health risks but to the fact that NMN was being studied as an Investigational New Drug (IND). Consequently, NMN’s designation as a legal supplement was thrown into limbo, because:

• Per the Dietary Supplement Health and Education Act of 1994, the term dietary supplement does not include “an article authorized for investigation as a new drug, antibiotic, or biological for which substantial clinical investigations have been instituted and for which the existence of such investigations has been made public.”27
• As an IND, NMN would have to be authorized by the FDA for administration in humans.28

In response, the Natural Products Association filed a lawsuit against the FDA based on the fact that NMN had been sold as a supplement long before the start of its IND-related studies. Then, in 2024, a federal court issued a motion to suspend legal proceedings on the case.29 The suspension effectively allowed NMN to continue being sold on the market as a supplement.

NMN’s high oral bioavailability makes it superior to NAD as a supplement. Even NAD enhanced with bioavailability-enhancing encapsulation (e.g., liposomal) isn’t likely to have as desirable an impact as NMN.

The more pertinent question, then, is this: How do you choose an NMN supplement?

The chief thing to look at is the dose. Quantities as low as 300mg have been shown to be effective, but NMN is relatively dose-dependent, so you’d do well to focus your search on products that offer at least 600mg per serving.30 31

Ideally, too, you want the NMN not as a standalone supplement but as part of a complex that includes ingredients that help populate your methyl pool, either directly or by boosting by-products in NAD+ metabolism. Otherwise, your NAD+ levels may rise for a few weeks only to plateau and then decline once your methyl groups have been depleted. Supporting players like TMG and spermidine (at minimum doses of 500mg and 15mg, respectively) can prevent plateaus and declines from happening.

Lastly, an optional but highly recommended addition to your NMN supplement would be nicotinamide riboside (NR), the other principal precursor in the salvage pathway. Although NR’s role in the pathway is to become NMN, it also penetrates cells through a separate entry point, potentially increasing the efficiency of your NAD+ production (think of two work teams constructing separate ends of a wall and converging in the middle). Furthermore, it provides its own health benefits, namely the ability to prevent the onset of neurodegenerative pathologies such as Alzheimer’s.