What is NAD+? It is nicotinamide adenine dinucleotide, a coenzyme present in every cell in the body and essential to how those cells extract energy from food. It is not a peptide, it is not synthetic, and it is not a drug. It is a molecule you already make and already depend on continuously.
The vendor we point lifters to
NAD+ from Ascension Peptides
Independently assayed material, dispatched from the US. The vial drops by half with the code below.
Quoted per 100 mg because NAD+ is dosed in hundreds of milligrams, not the single milligrams a peptide vial holds. Buying 3, 5 or 10 takes 3%, 5% or 10% off the list price. Free shipping starts at $250.
- Two independent lab reports per batch
- Free delivery above $250
- Same-day dispatch on orders before 2pm CST
Research material, laboratory use only, not for human consumption. Affiliate links: we may earn a commission at no extra cost to you. Pricing verified August 20, 2026.
That makes it different in kind from everything else covered on this site. Most compounds here are synthetic peptides with thin evidence and confident marketing. This one is fundamental biochemistry with an enormous scientific literature and a very specific problem attached.
The problem is that most of that literature studies something other than what is being sold.
What is NAD+ doing that a cell cannot manage without
Two jobs, and the distinction between them explains almost everything else.
In its first job, NAD+ is an electron carrier. It accepts electrons stripped from fuel molecules, becoming NADH, and delivers them to the mitochondrial electron transport chain where the energy is captured. Then it returns to the oxidised form and does it again. In this role the molecule is not used up. It cycles, and what matters is the size of the pool available to keep cycling.
In its second job, NAD+ is a substrate that gets consumed. Enzymes including the sirtuins, the PARPs involved in DNA repair, and CD38 cleave NAD+ as part of their normal activity, releasing nicotinamide as a by product. Every one of those reactions removes a molecule from the pool.
So the total amount available reflects a balance: consumption on one side, resynthesis on the other. When people talk about NAD+ declining, this balance is what they are describing.
The salvage pathway, and where precursors enter
The body rebuilds NAD+ mostly by recycling. The nicotinamide released by the consuming enzymes is picked up and converted back, through an intermediate, into NAD+ again. This route is called the salvage pathway, and its rate limiting enzyme is NAMPT.
That pathway is also the door through which supplements enter, and it is why almost everything sold in this category is a precursor rather than NAD+ itself.
| Molecule | What it is | How it relates to NAD+ | How it has been studied in humans |
|---|---|---|---|
| NAD+ | The coenzyme itself | The end product cells actually use | Mostly as intravenous infusion, with a thin controlled record |
| Nicotinamide riboside | A precursor | Converted toward NAD+ via the salvage pathway | Orally, in a substantial trial literature |
| Nicotinamide mononucleotide | A precursor, one step further along | Converted to NAD+ | Orally, in a growing trial literature |
| Nicotinamide | A precursor and a by product of NAD+ consumption | Recycled through the salvage pathway | Orally, long established as a vitamin form |
| Nicotinic acid | A precursor, the classic form of niacin | Enters by a separate route | Orally, long established, known for flushing |
Every row studied in humans by mouth is a different intervention from the vial in the first row. That is the whole issue, laid out.
What is sold under the name, and how the versions differ
Three products share the abbreviation and they are not interchangeable.
Oral precursor capsules are the version with the real human trial record. Intravenous NAD+ is administered in clinics over hours and has a much thinner published record. Subcutaneous NAD+ from a research vial has the least behind it of the three, and no approved product exists in any market.
There is also an unresolved mechanistic question about the injected forms. NAD+ is a large, charged dinucleotide, and published biochemistry describes extracellular NAD+ being broken down at the cell surface by enzymes including CD38 into smaller pieces, such as nicotinamide riboside and nicotinamide, before uptake. If that is the dominant route, injecting NAD+ largely amounts to delivering precursors invasively.
That is a mechanistic argument rather than a settled conclusion. It has not been resolved by a trial comparing routes with tissue level outcomes in people, and it should be presented as an open question. It is enough, though, to stop anyone treating the oral literature as evidence for the vial.
How the pool is regulated, and why that matters
The size of the NAD+ pool is not simply a matter of how much raw material arrives. It is actively managed, and three features of that management explain why supplementation has been harder to translate than the premise suggests.
Resynthesis is rate limited. NAMPT sets the pace of the salvage pathway, and flooding the system with precursors does not necessarily raise output past what the enzyme step allows.
Consumption rises with age. CD38 activity has been reported to increase with age in tissue studies, and DNA repair enzymes draw on the same pool as damage accumulates. A declining level can therefore reflect greater demand rather than insufficient supply, and adding material to the supply side does not address demand.
And tissues differ. Skeletal muscle maintains its own NAD+ largely through the local salvage pathway, which is one proposed explanation for why blood levels and muscle levels have moved independently in human trials of oral precursors.
None of that means supplementation cannot work. It means the system is a regulated one rather than a tank to be filled, and simple arguments from a low reading to a needed top up skip most of the biology.
The decline with age, described carefully
Declining NAD+ levels with age have been reported in rodent tissues and in human tissue measurements. Proposed mechanisms include increased consumption by CD38 and by DNA repair activity as damage accumulates.
That is a genuine observation. What it is not is proof that the decline drives ageing, or that reversing the measurement reverses anything downstream. Restoring a number to a youthful value is not the same as restoring the tissue the number came from, and this field has already run into exactly that distinction: trials of oral precursors in older adults raised NAD+ metabolites in blood while effects measured in skeletal muscle were limited or absent.
Four things NAD+ is not
It is not a peptide, despite being sold beside them. It is a dinucleotide, structurally unrelated.
It is not approved as an injected medicine anywhere, so an injected product has no pharmacopoeial standard, no accountable manufacturer and no verified concentration.
It is not anabolic. There is no described interaction with myostatin, with satellite cell behaviour or with muscle protein synthesis in any species. No trial of oral precursors or of injected NAD+ has reported an increase in muscle mass or in strength.
And it is not the subject of most of the studies cited in its support, which studied precursors taken by mouth.
A very large literature that mostly is not about the vial
Anyone searching this topic will find an enormous body of scientific work, and the size of it does a lot of persuasive work on sales pages.
The literature is genuinely large and genuinely serious. It spans fundamental biochemistry, ageing biology, mitochondrial physiology and a substantial run of human trials. Nothing about that is exaggerated.
What is exaggerated is the implication that this weight of evidence stands behind an injected product. The human interventional work is dominated by oral precursors. The rodent work is mostly precursors too. Injected NAD+, the thing actually being marketed to lifters, sits at the thin end of a very thick literature, and it borrows the thickness by sharing an abbreviation.
The rule that follows is simple and worth applying to every claim encountered on this subject: ask which molecule was given, and by which route. If the source does not say, it is not reporting evidence, it is reporting an association between three characters and a large number of papers.
Why a site about ageing muscle has to be careful here
The connection to this audience is real but indirect, and it is easy to overstate.
Mitochondrial function matters to how an older lifter tolerates training volume and recovers between sessions, and NAD+ is genuinely central to mitochondrial energy metabolism. That is a coherent reason to follow the research and a poor reason to buy anything, because the step from coenzyme biology to a training outcome has not been demonstrated in human muscle.
There is one intervention with human evidence in the relevant tissue, and it is training itself. Exercise training has been reported in humans to increase expression of the salvage pathway enzyme NAMPT in skeletal muscle. The best supported way to act on muscle NAD handling is the thing the reader is already doing.
Common questions about the molecule
Is NAD+ a peptide?
No. It is a dinucleotide coenzyme made in the body, structurally unrelated to the peptides sold alongside it.
Is the human evidence about NAD+ or about precursors?
Overwhelmingly about oral precursors, principally nicotinamide riboside and nicotinamide mononucleotide. Statements about extensive human study almost always refer to those rather than to injected NAD+.
Does the body make it naturally?
Yes, continuously, mainly by recycling nicotinamide through the salvage pathway, with contributions from dietary precursors including the niacin forms.
Does it do anything for muscle mass?
No study of either form, in any species, has reported an increase in muscle mass or strength, and there is no mechanism connecting it to muscle growth signalling.