NAD+ supplements: NR, NMN and what the trials measured

An NAD supplement is a capsule or powder sold to raise the body’s NAD+, usually by supplying a building block such as nicotinamide riboside (NR) or nicotinamide mononucleotide (NMN). In short human trials, NR and NMN do raise NAD+ in the blood, but none is FDA-approved to treat anything and no trial has shown that one slows aging.

NAD+ (nicotinamide adenine dinucleotide) is a coenzyme cells use to turn food into energy. Levels are reported to fall with age, which is the idea behind “NAD+ boosting.” This guide covers oral supplements only: what’s in them, where each stands with the FDA, what the trials measured, and the side effects reported. Injections and IV drips are a different, prescription product, covered in our NAD+ therapy guide.

What’s in an NAD+ supplement

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Niacin (nicotinic acid) is another form of vitamin B3 the body can use to make NAD+. Above about 50 mg a day it can cause flushing, according to the authors of a 2019 NR trial. In that trial, NR caused no flushing.

FDA status: what “sold as a supplement” means

NMN. The FDA’s position changed twice. In October and November 2022 it told companies NMN was excluded from the definition of a dietary supplement, because NMN had been authorized for investigation as a new drug first. On September 29, 2025, it granted a citizen petition in part and wrote: “we now conclude that NMN is not excluded from the dietary supplement definition.” The FDA said it was aware of evidence that NMN was marketed as a supplement in the US as early as 2017. It also said that “a product’s safety profile does not determine” the legal question it was deciding. In other words, the 2025 decision is about whether NMN may be sold as a supplement, not whether it is safe or works.

NR. In 2016 the FDA closed GRAS notice 635 for nicotinamide riboside chloride with a “no questions” letter, covering its use as a vitamin B3 source in some foods and drinks. The authors of a 2019 trial report that the same ingredient was also the subject of 2 new dietary ingredient notifications for supplements, in 2015 and 2018.

The rules for all of them. Under the 1994 supplement law, the FDA “does not have the authority to approve dietary supplements before they are marketed” (FDA). A product sold as a supplement that claims to treat, prevent or cure a disease is regulated as a drug. Making sure a supplement is safe and contains what its label says is the maker’s job.

NR vs NMN: what the trials measured

The only head-to-head comparison we found is a 2026 trial in Nature Metabolism. 65 healthy adults took a placebo, nicotinamide (500 mg), NR (1,000 mg) or NMN (1,000 mg) once a day for 14 days. NR and NMN raised NAD+ in the blood by similar amounts; nicotinamide did not. The study was open-label, lasted 2 weeks, and was run by researchers employed by Nestlé.

Other trials tested one ingredient against placebo. These are reported as what was measured and found.

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Pooled reviews give the broader picture:

• A 2026 systematic review found 33 human studies (28 randomized). Oral NR and NMN consistently raised NAD+-related markers in blood and were generally well tolerated over weeks to months. Effects on function, metabolism, blood vessels and other healthy-aging outcomes were mixed and often null. The authors called clinical effectiveness for anti-aging or wellness “inconclusive.”
• A 2026 meta-analysis of 15 NMN trials found no effect on body weight, BMI, fasting glucose, HbA1c, cholesterol or systolic blood pressure; diastolic blood pressure fell slightly.
• A 2025 meta-analysis in adults over 60 found NMN didn’t change muscle mass, grip strength or walking speed, and concluded the evidence doesn’t support NMN or NR for preserving muscle.

What the trials didn’t show

No trial of an NAD+ supplement has measured aging or lifespan in people. Raising a level in the blood isn’t the same as changing something you would feel or that would affect your health. Most trials ran for weeks, the longest NMN trials in the 2026 analysis ran 24 weeks, and several were funded or run by companies that make or sell these ingredients.

NAD supplement side effects

In short trials, side effects were uncommon and mild:

• NMN. The 2026 meta-analysis of trials at 250 to 2,000 mg a day for 14 days to 24 weeks found no increase in overall, serious or system-specific side effects, or in liver enzymes, compared with placebo.
• NR. In the 8-week Conze trial at up to 1,000 mg a day there were no reports of flushing and no difference in side effects from placebo. In the Dollerup trial at 2,000 mg a day for 12 weeks, there were no serious side effects and safety blood tests were normal.
• Head to head. In the 2026 comparison, 3 of 65 people had a side effect judged probably related to the product: stomach pain on placebo, low blood pressure on NR and a headache on NMN.
• NADH and precursors. A 2024 review of 10 randomized trials (489 people) listed muscle pain, nervous-system complaints, fatigue, sleep problems and headaches as the most common complaints, none serious.

What isn’t known is long-term safety, because no trial has run for years. The FDA also notes that some supplements can interact with medicines, interfere with lab tests or cause problems during surgery, so tell your clinician and pharmacist about any NAD+ product you take. Our guide to NAD+ side effects covers injections and IV drips.

How to choose an NAD+ supplement

We don’t rank or sell supplements, and no trial shows one brand is better than another. If you decide to take one:

• Check the compound. NR and NMN have the most human data. Nicotinamide is cheaper but didn’t raise blood NAD+ in the 2-week comparison. NAD+ or NADH capsules have the fewest trials.
• Check the amount. The trials above used NR at 100 to 2,000 mg a day and NMN at 250 to 2,000 mg a day. A label that hides the amount in a “proprietary blend” makes that comparison impossible.
• Look for outside testing. The FDA doesn’t check contents before sale, so a product tested by an outside lab against its label gives you some assurance the label is accurate.
• Skip disease claims. Under FDA rules, a product that claims to treat or prevent a disease is a drug, not a supplement.
• Tell your clinician, especially if you take prescription medicines or have surgery planned.

We don’t track supplement prices.

NAD+ supplements vs NAD+ injections

NAD+ injections, nasal sprays and IV drips are a different category. They need a prescription and are compounded by a pharmacy for an individual patient. NAD+ is not FDA-approved; the FDA lists it in Category 1 of its 503A bulk substances list, an interim policy under which it doesn’t intend to act against licensed pharmacies that compound it. That is enforcement discretion, not approval. The 2026 systematic review found no outcome trials of injected or intravenous NAD+ for anti-aging or wellness. Our NMN vs NAD+ guide compares the two directly, the NAD+ page has the legal detail, and our NAD+ provider rankings compare the clinics that prescribe injections.

The bottom line

Oral NAD+ supplements, mainly NR and NMN, reliably raise NAD+ in the blood in trials lasting days to months, and side effects in those trials were few. What they haven’t shown is a consistent benefit for metabolism, muscle or any other outcome people buy them for, and no trial has tested aging or lifespan. NMN has been allowed as a supplement since September 29, 2025; that decision was about the law, not about safety or effectiveness. If you try one, choose a product that states its compound and dose, and keep your clinician informed. For the wider field, see is longevity medicine legit and the longevity hub.