NAD+ and Healthy Aging: A Cardiologist’s Guide to Choosing an NMN Supplement

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NAD+ and Healthy Aging: A Cardiologist’s Guide to Choosing an NMN Supplement

Written By Dr. Don Zone, MD, FACC, FAARM

Few supplements have climbed as fast as NAD+ boosters. Ten years ago, nicotinamide adenine dinucleotide was a molecule mostly discussed in biochemistry lectures. Today it fills podcast episodes, wellness-clinic menus and an entire aisle of online stores. As a cardiologist, I get asked about it almost every week, usually by patients who have already bought something and want to know whether it was worth the money.

The honest answer is that NAD+ science is promising and the marketing is often far ahead of it. Here’s what NAD+ actually does, what the human research shows so far, and how to tell a thoughtfully formulated product from an expensive bottle of hope.

What NAD+ Does in Your Body

NAD+ is a coenzyme found in every living cell. Its best-known job is in energy production: inside your mitochondria, NAD+ shuttles electrons through the chain of reactions that turns food into ATP, the molecule cells use for fuel. Your heart, which beats around 100,000 times a day, is one of the most energy-hungry organs you have, which is one reason cardiologists pay attention to this pathway.

NAD+ also acts as a fuel for enzymes involved in DNA repair and cellular maintenance, including a family of proteins called sirtuins. Those roles are why researchers became interested in NAD+ as a possible lever on healthy aging.

The catch is that NAD+ levels appear to fall as we get older. Studies in human tissue suggest levels decline across adulthood, and that cells use NAD+ faster under chronic stress, inflammation and metabolic strain. The idea behind supplementation is simple: if you can give the body the raw materials to make more NAD+, you may be able to support the processes that depend on it.

Why Supplements Use NMN or NR Instead of NAD+

You’ll notice that most serious products don’t contain NAD+ itself. That’s deliberate. NAD+ is a large molecule that is broken down in the digestive tract, so swallowing it is an inefficient way to raise levels inside cells.

Instead, most products use a precursor: a smaller building block the body converts into NAD+. The two most studied are:

• Nicotinamide mononucleotide (NMN), which sits one step away from NAD+ in the body’s production pathway.
• Nicotinamide riboside (NR), a form of vitamin B3 that is converted to NMN and then NAD+.

Both reliably raise NAD+ levels in the blood in human trials. NR has been studied for longer. NMN’s research base is newer, but it has grown quickly and now includes several randomized, placebo-controlled trials.

What the Human Research Shows So Far

Most early NAD+ excitement came from mouse studies, and results in animals don’t always carry over to people. So it’s worth looking only at human data.

In a 12-week trial of older Japanese men published in npj Aging in 2022, 250 mg of NMN a day raised blood NAD+ compared with placebo, with some signals of improved walking speed and grip strength. Those muscle findings were modest and need confirmation in larger studies.

A 2023 trial in GeroScience is especially useful because it compared doses. Eighty healthy middle-aged adults took 300, 600 or 900 mg of NMN daily, or a placebo, for 60 days. NAD+ rose in every NMN group, and walking endurance improved. The gains increased from 300 to 600 mg, but going up to 900 mg added no further benefit. That’s a helpful reminder that more is not automatically better.

Across these studies, NMN was well tolerated, with side effects similar to placebo. What we don’t yet have is long-term data measured in years, or proof that raising NAD+ changes hard outcomes like heart disease or lifespan in humans. Anyone who tells you otherwise is getting ahead of the evidence.

On the regulatory side, the U.S. Food and Drug Administration confirmed in September 2025 that NMN can be sold as a dietary supplement, reversing an earlier position. That settled the question of whether you can legally buy it, but it says nothing about the quality of any individual product.

Five Things to Check Before You Buy

If you decide NAD+ support makes sense for you, these are the questions I’d ask about any product.

1. Is the dose in the studied range? Human trials have mostly used 250–600 mg of NMN per day. Products advertising 1,000 mg or more cost more without clear evidence of extra benefit.

2. Can the company prove what’s in the bottle? Look for independent certification (such as NSF or ConsumerLab) or published batch Certificates of Analysis showing purity, potency and heavy-metal testing. A vague “lab tested” claim with no documents behind it shouldn’t reassure you.

3. Is the delivery form evidence-based or marketing? Liposomal, sublingual and “enhanced absorption” versions often cost significantly more. So far, no published human trial shows liposomal NMN raises NAD+ more than a standard capsule at the same dose.

4. Does the formula make sense as a whole? Multi-ingredient products may combine NMN with nutrients such as CoQ10, magnesium, B vitamins and vitamin D, but evidence that these combinations improve the effects of NMN is limited. When comparing products, check the dose and purpose of each ingredient rather than assuming a larger formula is better. One example is an NMN supplement from Anti-Aging Today that combines 300 mg of NMN with CoQ10, magnesium malate, methylated B vitamins and vitamin D3/K2.

5. What does it cost per daily serving? NAD+ support only helps if you take it consistently, so compare the price per day, not per bottle.

Who Should Be Cautious

NAD+ precursors aren’t right for everyone. Talk to your doctor first if any of these apply:

• You’re pregnant or breastfeeding, because there’s no safety data in these groups.
• You have active cancer or a recent cancer history. Some laboratory research raises a theoretical concern that boosting cellular energy could also support tumor cells.
• You take warfarin or other blood thinners. Many longevity formulas include vitamin K2 or resveratrol, which can interact with these medications.
• You take several prescription drugs, especially for heart rhythm, blood pressure or diabetes.

And if you’re in your twenties or early thirties and healthy, the case for supplementing is weak. Most trials enrolled middle-aged and older adults, whose NAD+ levels are lower to begin with.

The Bottom Line

NAD+ boosters aren’t a fountain of youth, and they don’t replace the basics that drive healthy aging: regular exercise, good sleep, a mostly whole-food diet and keeping blood pressure, cholesterol and blood sugar in check. Exercise, in fact, is one of the most reliable ways to support NAD+ production on its own.

NMN and NR are among the more studied NAD+ precursors, but evidence of meaningful long-term clinical benefit remains limited. Choose a product with transparent dosing and independent testing when available. For readers comparing formulations, Anti-Aging Today lists longevity supplements selected by a cardiologist, and any supplement you’re considering can be discussed with your doctor or pharmacist.

About the author: Dr. Don Zone, MD, FACC, FAARM, is a board-certified cardiologist and Fellow of the American Academy of Anti-Aging Medicine. He is the founder of Anti-Aging Today and formulated Longevion, a longevity supplement mentioned in this article, in which he has a financial interest.

This article is for educational purposes only and is not medical advice. Supplements are not intended to diagnose, treat, cure or prevent any disease.