Question 1

What is NAD+?

Accepted Answer

A dinucleotide coenzyme found in living cells, described in the peer-reviewed literature as a coenzyme for redox reactions and an essential cofactor for non-redox enzymes including sirtuins, CD38 and poly(ADP-ribose) polymerases. It is not a peptide, and it is chemically distinct from the precursors and vitamin forms sold under related names.

Question 2

Is NAD+ the same thing as NMN or NR?

Accepted Answer

No. PubChem records them as three separate compounds with three different molecular formulas: NAD+ is C21H27N7O14P2, nicotinamide riboside is C11H15N2O5+, and nicotinamide mononucleotide is C11H15N2O8P. NR and NMN are precursors that cells can use to make NAD+; they are not NAD+. A result obtained with one is not a result for another, and most of the human trial literature quoted in consumer material about "NAD+" was run with a precursor.

Question 3

How does NAD+ relate to vitamin B3?

Accepted Answer

The Institute of Medicine's reference-intake chapter defines niacin as covering nicotinamide and nicotinic acid, and states that niacin functions through two coenzymes, NAD and NADP. So the vitamin is the dietary input and NAD is one of the coenzymes the body builds from it. The same chapter records the conversion factor of 60 mg of tryptophan to 1 mg of niacin equivalents. The vitamin's reference values are values for the vitamin, not for this compound.

Question 4

Is NAD+ an approved medicine?

Accepted Answer

No approved product containing it was located anywhere during data entry. The regulatory record for the substance in the United States consists of an evaluation as a bulk drug substance for compounding, in which FDA proposed not to add it to the 503A Bulks List, and a statement in a 2026 warning letter that it does not appear on the 503B bulks list. It does carry an assigned INN, USAN and JAN under the name nadide — which records that naming bodies have named the molecule, not that any authority has approved it.

Question 5

What did FDA say when it looked at NAD+?

Accepted Answer

It said there was not enough information to judge. In a Federal Register notice published on September 5, 2019, FDA wrote that nonclinical data in the literature are inadequate to characterise the potential toxicity profile for NAD, that it did not find sufficient clinical data to evaluate whether NAD is safe for use in compounded drug products, and that it identified no published studies supporting the use for which the substance had been nominated. FDA's advisory committee voted against adding it to the 503A Bulks List at a meeting held on May 8, 2017.

Question 6

Has FDA ever said anything specifically about intravenous NAD+?

Accepted Answer

Yes, twice and by name. On a compounding page FDA states that it is aware of compounders using food-grade nicotinamide adenine dinucleotide sold by repackagers to make intravenous products, that food-grade ingredients are not suitable for compounding sterile drugs because of contamination risk, and that it has received adverse event reports following use of NAD+ injectable drugs including severe chills, shaking, vomiting and fatigue, which it describes as consistent with excessive endotoxin levels. A separate warning letter records a compounded NAD+ product testing at 3,360 EU/mL of bacterial endotoxins.

Question 7

What happens to NAD+ given directly into the bloodstream?

Accepted Answer

One pilot study has looked. Grant 2019 stated that before its own work no data existed on the fate of directly infused NAD+ in people, and reported that during a 6 h infusion no change in plasma NAD+ or its metabolites was seen until after 2 h, that the compound was rapidly and completely removed from plasma over that period, and that the metabolite pattern was consistent with NAD+ glycohydrolase and pyrophosphatase activity. That is the whole of the published human record on the question.

Question 8

Does it matter whether a precursor is swallowed or infused?

Accepted Answer

Yes, and a tracer study measured the difference. Liu 2018 reports that nicotinamide riboside and nicotinamide mononucleotide given intravenously delivered intact molecules to multiple tissues, while the same agents given orally were metabolised to nicotinamide in the liver. A study of an oral precursor and a study of the same precursor infused are not the same experiment, and neither is a study of the coenzyme.

Question 9

Are there null results in this literature?

Accepted Answer

Several, in the precursor trials. A randomised placebo-controlled trial in obese, insulin-resistant men concluded that nicotinamide riboside does not improve insulin sensitivity or whole-body glucose metabolism, with no effect on resting energy expenditure, lipolysis, lipid oxidation or body composition. A separate crossover trial in overweight and obese volunteers found no effect on insulin sensitivity, mitochondrial function, liver or muscle lipid, cardiac measures, blood pressure, inflammation markers or energy metabolism, despite raising muscle NAD+ metabolites. Both are worth reading beside the positive trials.

Question 10

What is NMN's legal position in the United States?

Accepted Answer

It changed. Responding to a citizen petition under Docket Number FDA-2023-P-0872, FDA amended its earlier determination that NMN is excluded from the dietary supplement definition, writing that although NMN was authorised for investigation as a new drug and substantial clinical investigations had been instituted and made public, NMN was marketed as a dietary supplement in the United States before that authorisation. FDA added that it is aware of evidence of such marketing as early as 2017 and that it will no longer evaluate whether the prior marketing was lawful. That determination is about NMN, not about NAD+.

Question 11

And nicotinamide riboside?

Accepted Answer

A different track again. FDA's GRAS notice inventory records GRN No. 635 for nicotinamide riboside chloride, notified by ChromaDex, for use as a source of vitamin B3 in specified foods and beverages, closed in August 2016 with the response that FDA has no questions. A no-questions response on a food-use GRAS notice is not a drug approval and says nothing about the coenzyme or about any intravenous product.

Question 12

How should NAD+ be stored?

Accepted Answer

No authority has determined it. There is no pharmacopoeial monograph and no approved product label for this substance. What is on the record is FDA's stability assessment, which states that NAD degrades substantially when exposed to light, moisture, alkaline pH or standard room temperatures, and would not be stable under ordinary storage conditions without multiple compensatory measures. Any specific temperature or shelf-life figure circulating for this compound traces to a supplier page rather than to a determination by anyone.

Question 13

Why do searches for NAD+ trials return so many results?

Accepted Answer

Because the search is matching names, not molecules. A ClinicalTrials.gov intervention query for nicotinamide adenine dinucleotide returns 264 studies, but only 14 of them name NAD or nicotinamide adenine dinucleotide in an intervention at all; 50 name nicotinamide riboside or Niagen and 10 name NMN. One of the 14 is a cardiopulmonary resuscitation study in which NAD abbreviates Neighborhood Access Defibrillation. Read the intervention field of a registry record before counting it as evidence.

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