In short
NAD+ (nicotinamide adenine dinucleotide) is a coenzyme of about 663 Da built from two nucleotides, not a peptide. Its levels fall with age in human tissue, which drives interest in it. Oral precursors raise NAD+ metabolites in human trials, but functional benefits remain inconsistent, and for NAD+ itself there are no outcome trials.
- Age decline in humans: in skin from 49 people aged 0 to 77, NAD+ fell with age in both sexes (Massudi 2012, PLoS One)
- Evidence base 2026: a systematic review found 113 studies, 33 of them in humans; target engagement was consistent, functional effects were often null (Gallagher 2026, Ageing Res Rev)
- Infused NAD+: plasma NAD+ did not rise for the first 2 hours of a 6 hour infusion (Grant 2019, Front Aging Neurosci)
- Batch quality: batch ATNAD-100-2608-01 shows 99.12 % HPLC purity and 0.32 % of the inactive alpha anomer, analysed by Analyton Labs
Molequa® supplies NAD+ exclusively for laboratory research (RUO), not for use in humans.
What is NAD+, and why is it not a peptide?
NAD+ consists of two nucleotides, one carrying nicotinamide and one carrying adenine, joined by a pyrophosphate bridge. It contains no amino acids, so it is not a peptide, although many peptide shops list it. In cells it serves as a redox coenzyme and as a substrate for sirtuins, CD38 and poly(ADP-ribose) polymerases.
These enzymes link NAD+ to energy metabolism, DNA repair and chromatin remodelling. A 2021 review describes a gradual decline of tissue and cellular NAD+ during ageing in rodents and humans, and lists the open questions: how to restore levels effectively, whether doing so is safe and whether it benefits ageing people (Covarrubias 2021, Nat Rev Mol Cell Biol). In mice, one mechanism has been traced: inflammatory macrophages that accumulate in fat tissue and liver with age express the NAD+ consuming enzyme CD38 and lower tissue NAD+ (Covarrubias 2020, Nat Metab).
The human data on the decline are measured, not assumed. In pelvic skin samples, NAD+ correlated negatively with age in men (r = −0.706) and women (r = −0.537), while PARP activity rose with age in men (Massudi 2012). In plasma from people aged 20 to 87, NAD+ and NADP+ fell with age, while NADH, nicotinamide and ADP-ribose rose (Clement 2019, Rejuvenation Res).
What do human studies show?
Most human trials test precursors, not NAD+ itself. Nicotinamide riboside (NR) and nicotinamide mononucleotide (NMN) raise NAD+ metabolites and are generally well tolerated over weeks to months. Effects on function differ between trials, and a 2026 systematic review found no eligible outcome trial of NAD+ given by infusion or injection.
In a randomised, placebo controlled crossover trial with two 6 week phases, NR was well tolerated and stimulated NAD+ metabolism in healthy middle aged and older adults (Martens 2018, Nat Commun). A 10 week randomised trial of NMN in postmenopausal women with prediabetes reported higher muscle insulin sensitivity measured by clamp (Yoshino 2021, Science). Of the 33 human studies in the 2026 review, 28 were randomised; the review that clinical effectiveness for anti-ageing or wellness outcomes remains inconclusive (Gallagher 2026).
NAD+ itself behaves differently in the body. During an intravenous infusion, it was removed from plasma so quickly that no change appeared for 2 hours, and the metabolites pointed to breakdown by glycohydrolase and pyrophosphatase enzymes (Grant 2019). A 2026 retrospective review from a commercial infusion setting recorded moderate to severe gastrointestinal symptoms, faster heart rate and chest pressure during NAD+ infusions, which stretched infusion time to 97 minutes on average (Reyna 2026, Front Aging).
NAD+, NMN and NR compared
NAD+, NMN and NR belong to the same metabolic pathway but differ in size and in how they are studied. NMN and NR are smaller precursors tested orally in human trials. NAD+ is the active coenzyme and the form used directly in enzyme assays.
| Feature | NAD+ | NMN | NR |
|---|---|---|---|
| Chemical class | dinucleotide coenzyme | mononucleotide precursor | nucleoside precursor |
| Approximate size | about 663 Da | about 334 Da | about 255 Da |
| Typical use in research | enzyme assays with sirtuins, PARP, CD38 | oral human trials, animal models | oral human trials, animal models |
| Human outcome trials | none eligible for infused NAD+ | several, results mixed | several, results mixed |
NMN and NR have to be converted inside cells, while NAD+ given from outside is broken down quickly in plasma, as the infusion study showed.
Another compound studied in cellular energy research, the mitochondrial peptide MOTS-c, is covered in the MOTS-c peptide guide.
What to check before an NAD+ purchase
For NAD+, purity alone is not enough. The certificate should also show the content of active beta NAD+, the inactive alpha anomer, the reduced form NADH, the salt form and the water content. The alpha anomer has the same mass as beta NAD+, so mass spectrometry cannot detect it, only chromatography and an enzymatic assay can.
The certificate for Molequa® batch ATNAD-100-2608-01, issued by the independent laboratory Analyton Labs, reports:
- HPLC purity 99.12 %, identity by mass spectrometry at m/z 664.1168 with 0.6 ppm deviation
- beta NAD+ content 94.80 %, confirmed enzymatically at 94.90 %
- alpha anomer 0.32 % and NADH 0.14 %
- free acid form with 0.03 % sodium, water 3.40 %
- 97.5 mg of beta NAD+ per vial labelled 100 mg
- endotoxins below 0.005 EU/mg and no growth in the sterility test after 14 days
The salt form changes how much NAD+ each milligram of powder holds; a mono sodium salt would contain 3.4 % sodium. The certificate also notes a pH of 3.2 and that above pH 7 NAD+ hydrolyses to ADP-ribose and nicotinamide. The certificate describes the powder as hygroscopic, so containers should stay closed and dry until use; it dissolves at 50 mg/ml or more in water to a clear, colourless solution. The batch number on the vial can be matched in the CoA checker, and how to verify a peptide supplier explains the remaining lines. The product page for an NAD+ purchase for research currently shows it as out of stock; you can reserve it there without payment.
Frequently asked questions
Is NAD+ a peptide?
No. NAD+ is a dinucleotide coenzyme made of two nucleotides joined by a pyrophosphate bridge. It contains no amino acids, even though peptide shops often list it.
Do NAD+ levels decline with age?
Human data say yes. NAD+ in skin correlated negatively with age in both sexes, and plasma NAD+ fell across ages 20 to 87.
Does taking NAD+ precursors work in humans?
Oral NR and NMN raise NAD+ metabolites and were generally well tolerated in trials. Effects on functional outcomes were mixed or null in many studies.
What is alpha NAD+?
An anomer of NAD+ with the same mass but enzymatically inactive. It is detected by chromatography and enzymatic assay, not by mass spectrometry. Batch ATNAD-100-2608-01 contains 0.32 %.
Why does the salt form matter?
Because it changes how much NAD+ is in each milligram of powder. The certificate should state whether the material is free acid or a sodium salt.
How should NAD+ be handled in the lab?
Keep the hygroscopic powder closed and dry until use. In solution NAD+ is more stable at acidic pH; above pH 7 it hydrolyses to ADP-ribose and nicotinamide.
Is Molequa® NAD+ intended for human use?
No. It is reference material exclusively for laboratory research (RUO), and Molequa® publishes no dosing information.
