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Research Reference · Cellular Energy & Longevity

NAD+

A coenzyme in every living cell, central to energy metabolism and DNA-repair enzymes — one of the most-studied molecules in aging research.

Last reviewed September 2026 8 peer-reviewed sources 3-minute read

At a glance

NAD+ (nicotinamide adenine dinucleotide) is not a peptide. It is a coenzyme present in every living cell, essential for turning nutrients into energy and used up by enzymes that regulate metabolism and repair DNA. NAD+ levels fall with age in many tissues, which has made it a major focus of aging research. Most human studies test its building blocks, NR and NMN, rather than NAD+ itself.

TypeCoenzyme (not a peptide)
Studied forCellular energy & aging
Evidence stageAnimal + human precursor trials
Human dataTrials of precursors (NR, NMN)

What it’s studied for

Energy metabolism

Carries electrons in the reactions that turn nutrients into usable energy. 3

Cell

Aging

NAD+ declines with age; restoring it improves some age-related changes in animals. 2,6

Animal & human

Sirtuins & DNA repair

Consumed by sirtuins and PARP enzymes that regulate metabolism and repair DNA. 4,5

Cell & animal

Raising NAD+

Precursors such as NR and NMN raise NAD+ metabolism in human trials. 7,8

Human trials

NAD+

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How it works

NAD+ shuttles electrons in the reactions that convert nutrients into usable cellular energy. It is also consumed as a substrate by enzymes such as sirtuins and PARPs, which regulate metabolism and repair DNA. 3,4

Studies in animals and people show NAD+ falls in several tissues with age. In old or diseased animals, restoring NAD+ can improve health, which prompted the search for safe NAD-boosting molecules. 2,6

Most human research gives NAD+ building blocks rather than NAD+ itself. Nicotinamide riboside (NR) was well tolerated and raised NAD+ metabolism in healthy middle-aged and older adults, 7 and nicotinamide mononucleotide (NMN) increased muscle insulin sensitivity in a trial of women with prediabetes. 8 Recent reviews stress that larger, longer studies are still needed. 3,1

Related research

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Frequently asked questions

Is NAD+ a peptide?
No. NAD+ is a coenzyme — a small helper molecule made of two nucleotides — found in every living cell.
What is the difference between NAD+ and NADH?
They are the oxidized (NAD+) and reduced (NADH) forms of the same molecule; the pair carries electrons in energy metabolism.
What are NR and NMN?
Nicotinamide riboside and nicotinamide mononucleotide — NAD+ building blocks (precursors) used in most human studies.
Does NAD+ decline with age?
Research in animals and people shows NAD+ levels fall in several tissues with age, which is why it is studied in aging research.
What is the CAS number of NAD+?
53-84-9. Its molecular formula is C21H27N7O14P2 (663.4 g/mol).

Identifiers

Name NAD+ (nicotinamide adenine dinucleotide, oxidized form)
Other names nadide · coenzyme I · β-NAD · diphosphopyridine nucleotide
Class Dinucleotide coenzyme (not a peptide)
Molecular formula C21H27N7O14P2
Molecular weight 663.4 g/mol
CAS number 53-84-9
PubChem CID 5892
Supplied as Powder

Identifiers checked against PubChem (CID 5892).

Research timeline

  1. 2014Review: NAD+ and sirtuins in aging and disease. 4
  2. 2015Review in Science: NAD+ in aging, metabolism and neurodegeneration. 2
  3. 2018Review of in-vivo evidence for NAD-boosting molecules 6; NR raises NAD+ metabolism in older adults. 7
  4. 2020Review: NAD+ homeostasis in health and disease. 5
  5. 2021NMN improves muscle insulin sensitivity in women with prediabetes 8; review of NAD+ in cellular processes during ageing. 3
  6. 2025Review of strategies and challenges in taking NAD+ research into the clinic. 1

Key studies

StudyModelWhat it found
Martens 2018 7 Human · crossover trial NR was well tolerated and raised NAD+ metabolism in healthy middle-aged and older adults.
Yoshino 2021 8 Human · randomized trial NMN increased muscle insulin sensitivity and signaling in women with prediabetes.
Rajman 2018 6 Review Restoring NAD+ in old or diseased animals can promote health and extend lifespan.
Covarrubias 2021 3 Review Much remains unknown about whether NAD+ repletion is safe and beneficial in ageing humans.

Sources

  1. Emerging strategies, applications and challenges of targeting NAD(+) in the clinic. Zhang J, et al. Nat Aging, 2025. Review
  2. NAD⁺ in aging, metabolism, and neurodegeneration. Verdin E. Science, 2015. Review
  3. NAD(+) metabolism and its roles in cellular processes during ageing. Covarrubias AJ, et al. Nat Rev Mol Cell Biol, 2021. Free full textReview
  4. NAD+ and sirtuins in aging and disease. Imai S, Guarente L. Trends Cell Biol, 2014. Free full textReview
  5. NAD(+) homeostasis in health and disease. Katsyuba E, et al. Nat Metab, 2020. Review
  6. Therapeutic Potential of NAD-Boosting Molecules: The In Vivo Evidence. Rajman L, et al. Cell Metab, 2018. Free full textReview
  7. Chronic nicotinamide riboside supplementation is well-tolerated and elevates NAD(+) in healthy middle-aged and older adults. Martens CR, et al. Nat Commun, 2018. Free full textHuman trial
  8. Nicotinamide mononucleotide increases muscle insulin sensitivity in prediabetic women. Yoshino M, et al. Science, 2021. Free full textHuman trial
For Research Use Only. This page summarizes published scientific research for educational purposes. It is not medical advice and does not promote, recommend, or describe any human or animal use. Products referenced are sold strictly for laboratory research and are not for human consumption.

Last reviewed September 2026 by Midwest Compounds. Every source above was checked against its original publication.