Longevity
NAD+ Explained
Also known as: NAD, Nicotinamide adenine dinucleotide, NAD plus
What is NAD+?
NAD+ (nicotinamide adenine dinucleotide) is a coenzyme found in every living cell. It shuttles electrons in energy metabolism and is a required fuel for enzymes that repair DNA (PARPs) and regulate ageing-related pathways (sirtuins). It is not a peptide, but it is sold and studied alongside peptides in longevity research.
The NAD meaning in medical shorthand is simply this molecule. NADH is its reduced (electron-carrying) form, and NADP is a phosphorylated relative used in biosynthesis and antioxidant defence.
How NAD+ works
Tissue NAD+ levels decline with age in animals and in several human tissues, partly because consumption by enzymes such as CD38 rises. Researchers try to restore levels in two ways: giving precursors (NMN or NR) that cells convert to NAD+, or giving NAD+ itself by infusion or injection. Infused NAD+ is largely broken down outside cells into smaller precursors that are then taken up, so the two approaches overlap more than marketing suggests.
What the research shows
- In mice, raising NAD+ improved mitochondrial function, insulin sensitivity and some markers of ageing.
- Human trials confirm oral NR and NMN raise blood NAD+ levels; effects on clinical outcomes (muscle function, insulin sensitivity, blood pressure) have been modest and inconsistent.
- Small human studies of IV NAD+ show that infusion raises plasma NAD+ but that fast infusions often cause flushing, nausea and chest tightness.
NAD+ side effects
Oral NMN and NR have been well tolerated in trials of up to several months. Injected or infused NAD+ commonly causes flushing, nausea, abdominal cramping, headache and a feeling of chest pressure, especially when given quickly — the reason clinics infuse slowly over hours.
UK legal status
NAD+ is not a licensed medicine in the UK. Oral precursors such as NR are sold as food supplements; NMN's status as a novel food is unresolved in the UK and EU. IV NAD+ is offered by private clinics as an unlicensed treatment. Lyophilised NAD+ vials are sold for research.
More detail, including current UK research-vial prices: NAD+ UK guide. For the doses used in published studies and the reconstitution maths: NAD+ dosing in the literature.
NAD+: frequently asked questions
What is NAD+?
Nicotinamide adenine dinucleotide, a coenzyme every cell uses for energy production, DNA repair and sirtuin signalling.
What is the difference between NAD+ and NADH?
They are the same molecule in two states. NAD+ is oxidised (ready to accept electrons); NADH is reduced (carrying electrons to the mitochondria).
Is NMN or NR better than NAD+?
Both reliably raise blood NAD+ when taken orally. Direct NAD+ is poorly absorbed by mouth and is broken down outside cells when injected, so precursors are the more studied route.
What does NAD+ do for ageing?
Animal studies link restored NAD+ to better mitochondrial and metabolic function. Human trials have so far shown modest benefits at best.
References
- Rajman L, Chwalek K, Sinclair DA. Therapeutic potential of NAD-boosting molecules: the in vivo evidence. Cell Metab. 2018;27:529–547.
- Covarrubias AJ, et al. NAD+ metabolism and its roles in cellular processes during ageing. Nat Rev Mol Cell Biol. 2021;22:119–141.
- Yoshino M, et al. Nicotinamide mononucleotide increases muscle insulin sensitivity in prediabetic women. Science. 2021;372:1224–1229.
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