NAD+ explained: the biology, the forms and the honest evidence

What NAD+ does

Every cell uses NAD+ to shuttle electrons in the reactions that release energy from food. The NIH Office of Dietary Supplements notes that more than 400 enzymes require NAD to work, and that it also supports genome integrity, gene expression and cell signaling.

Your body makes NAD+ from dietary niacin, which includes nicotinic acid, nicotinamide and nicotinamide riboside, and partly from the amino acid tryptophan. Most people who eat a varied diet get enough niacin to avoid deficiency.

Why it draws interest in midlife

Research in animals and people suggests NAD+ levels fall with age, and in lab models restoring NAD+ improves some measures of mitochondrial function and metabolism. That has made NAD+ an appealing target for people noticing lower energy, slower recovery or concern about aging.

It's important to keep the steps straight. Lower NAD+ with age is one finding; raising NAD+ in people is a second; showing that raising it improves how people feel or function is a third, and that third step is where the evidence is thin.

Ways to raise NAD+

• Oral precursors: nicotinamide riboside (NR) and nicotinamide mononucleotide (NMN) are the most studied. NR is sold as a supplement; the FDA ruled in 2022 that NMN can't be marketed as a dietary supplement because it was being investigated as a drug.
• Niacin itself: nicotinic acid and nicotinamide are inexpensive vitamins, though high doses of nicotinic acid cause flushing and have other side effects.
• Injections: NAD+ given under the skin, available through compounding pharmacies.
• Intravenous infusions and nasal sprays, which are offered by some clinics and have little published human data.

The honest evidence picture

A 2023 review in The Journals of Gerontology looked at human trials of NAD+-boosting supplements. It found they appear safe and well tolerated and can raise NAD+ and related compounds in several tissues. But the authors concluded that clinical evidence that raising NAD+ improves physiological function is unclear, partly because studies have been small, short and varied in dose.

Evidence for injected NAD+ is thinner still. Small studies have tracked how it is broken down, not whether it improves health outcomes. So any benefit you might notice from injections can't yet be predicted from trial data.

Regulatory status and safety

NAD+ injections are compounded by licensed pharmacies. They are not FDA-approved for any use, the FDA has not reviewed them for safety, effectiveness or quality and they aren't equivalent to any branded product. The FDA lists NAD in Category 1 of substances nominated for compounding, which means it is still under evaluation and may be used under the agency's interim policy.

Commonly reported effects with injections include injection-site discomfort, flushing, nausea and lightheadedness. Because long-term data are limited, people who are pregnant or breastfeeding, or who have active cancer, are generally advised to avoid it, and your clinician will review your medicines.

Separating the biology from the marketing

• True: NAD+ is essential to energy metabolism and declines with age.
• True: supplements and injections can raise NAD+ levels.
• Not shown: that this reverses aging, extends lifespan or reliably boosts energy in people.
• Worth remembering: fatigue in midlife often has a specific, testable cause, such as poor sleep, low iron, thyroid disease, high blood sugar or hormone changes.

A measured way to try it

• Check the basics first: sleep, alcohol, activity, iron, thyroid, blood sugar and hormones.
• Write down what you hope will change, such as afternoon energy or training recovery, and rate it for two weeks before starting.
• Keep everything else steady during the trial so you can tell what's helping.
• Review after an agreed period with your clinician and stop if there's no clear benefit.
• Report flushing, nausea, dizziness or injection-site problems promptly.

How HealifyMD approaches NAD+

Your clinician first looks for common causes of low energy, often with labs priced separately. If NAD+ is a reasonable experiment for you, injections are shipped from a licensed U.S. pharmacy from $199/month with no membership fee, confirmed at your eligibility review. You'll get injection training, a dose set by your clinician and a planned review to decide whether it's worth continuing.