NAD+

Research summary

NAD+ (nicotinamide adenine dinucleotide) is a coenzyme found in every living cell, not a peptide: it carries electrons in oxidation-reduction reactions and is consumed as a co-substrate by enzymes such as the sirtuins and poly(ADP-ribose) polymerases¹. Research interest has grown because tissue NAD+ levels decline with age in rodents and humans, a change studied in connection with mitochondrial function, DNA repair and metabolic regulation². Peptides Only supplies NAD+ as a lyophilized research reagent for laboratory use.

Also known as

Nicotinamide adenine dinucleotide · NAD · β-NAD · Nadide · NAD+ coenzyme

What is NAD+?

Nicotinamide adenine dinucleotide is, as the name says, a dinucleotide: a nicotinamide nucleotide and an adenine nucleotide joined through their phosphate groups. It is a small organic coenzyme rather than a chain of amino acids. It is listed alongside research peptides because it is used in the same mitochondrial and aging research, but chemically it belongs to a different class.

NAD+ has two distinct jobs. In its oxidized form it accepts electrons in metabolic reactions and becomes NADH, which passes those electrons on, most importantly to the mitochondrial respiratory chain^1,2. Separately, sirtuins, poly(ADP-ribose) polymerases (PARPs) and the NADase CD38 cleave NAD+ as a substrate, using it up rather than shuttling it between two states. Through these enzymes, NAD+ availability is connected to DNA repair, chromatin remodeling, cellular senescence and immune-cell function².

How cells make, move and use NAD+

Cellular NAD+ reflects a balance between production and degradation³. Nicotinamide, a form of vitamin B3, is one of its precursors. The enzyme nicotinamide N-methyltransferase (NNMT) methylates nicotinamide using S-adenosylmethionine, which ties NAD+ metabolism to the cell's methylation balance⁴; that link is why NNMT inhibitors such as 5-Amino-1MQ are studied in the same context.

NAD+ is also compartmentalized. Mitochondria hold a pool that is distinct from the cytosol and nucleus, and in 2020 researchers identified SLC25A51 as a mammalian transporter that imports intact NAD+ into mitochondria. Cells lacking it had lower mitochondrial, but not whole-cell, NAD+ and impaired respiration⁵. A measurement of total NAD+ therefore does not necessarily describe the mitochondrial pool.

What the research on NAD+ and aging has examined

Much of the field rests on the observation that NAD+ falls with age. In human pelvic skin samples from donors ranging from newborns to 77 years old, tissue NAD+ correlated inversely with age, while PARP activity and markers of DNA damage rose; the associations were clearer in males than in females⁶.

Mechanistic work has proposed why. Camacho-Pereira and colleagues reported that expression and activity of the NAD-degrading enzyme CD38 increase with aging and that CD38 was required for the age-related NAD decline and mitochondrial dysfunction they observed, acting at least partly through the mitochondrial sirtuin SIRT3⁷. Gomes and colleagues traced a loss of mitochondrially encoded respiratory-chain proteins in aging mice to falling nuclear NAD+, and reported that raising NAD+ in old mice restored mitochondrial function in a SIRT1-dependent manner⁸.

Reviews of the in vivo literature describe a consistent preclinical pattern, in which restoring NAD+ in old or diseased animals has been reported to promote measures of health and extend lifespan, while stressing that these findings come from animal models^2,9.

NAD+ itself vs NAD+ precursors

Most of the strategies discussed for raising NAD+ in living organisms rely on precursors that cells convert into NAD+, rather than on NAD+ itself¹. Precursors such as nicotinamide mononucleotide (NMN) and nicotinamide riboside (NR) are different molecules^7,10, so findings from precursor studies cannot be assumed to apply to the coenzyme.

Data on NAD+ given directly to people are sparse. In a small pilot study that tracked plasma and urine during an intravenous NAD+ infusion, plasma NAD+ and its metabolites did not change for the first two hours, and the metabolite pattern was consistent with breakdown by NAD+ glycohydrolase and pyrophosphatase activity¹⁰. The study characterized how NAD+ is metabolized; it did not assess health outcomes.

Limitations of the evidence

• Causal findings linking NAD+ to aging come mainly from mice and other model organisms; human data are largely correlational or come from small pilot studies^2,6,10.
• Reviews note that it is still unknown how best to restore NAD+ during human aging, whether doing so is safe, and whether it changes health in older people².
• NAD+ is compartmentalized, so changes in plasma or whole-cell NAD+ may not reflect the mitochondrial pool⁵.
• Reported associations vary by tissue and sex; in human skin, the links between age, PARP activity and NAD+ were weaker in females⁶.

Working with NAD+ in the lab

NAD+ is supplied as a lyophilized powder. Once dissolved, nicotinamide cofactors degrade over time; a 2024 study of NAD+ and NADH in common laboratory buffers found that both the choice of buffer and a modest rise in temperature measurably affected long-term stability¹¹. General guidance on handling lyophilized reagents is in our notes on peptide storage and stability.

Every Peptides Only lot ships from the USA with a lot-matched certificate of analysis from an independent lab, reporting HPLC purity and mass-spec identity. Certificates are published in the COA library.