NAD+ (nicotinamide adenine dinucleotide) is a coenzyme found in every living cell that plays a central role in energy metabolism and cellular repair. NAD+ levels decline with age, and that decline has been linked in animal models to markers of aging including mitochondrial dysfunction, reduced DNA repair capacity, and impaired cellular signaling.

The interest in NAD+ from a longevity standpoint is that raising intracellular NAD+ levels may support some of these cellular functions. The challenge is that NAD+ itself is too large to cross cell membranes effectively, which is why most supplementation strategies use precursors — molecules the body converts into NAD+.

NMN (nicotinamide mononucleotide) is one of the most studied NAD+ precursors. When consumed, NMN is converted by the body into NAD+ through enzymatic pathways, effectively raising intracellular NAD+ levels indirectly. NR (nicotinamide riboside) is another common precursor that works through a slightly different conversion pathway.

The key distinction: NMN is an oral supplement precursor, while NAD+ therapy at clinics typically refers to direct intravenous infusion of NAD+ itself — bypassing the conversion step entirely. Both aim to raise NAD+ levels, but the delivery method, the speed of effect, and the dose achievable are meaningfully different.

IV NAD+ therapy, offered by longevity clinics and mobile IV providers, delivers NAD+ directly into the bloodstream in large doses. This approach bypasses digestive conversion and is thought to raise NAD+ levels more rapidly and substantially than oral precursors. The tradeoff is cost — typically $300 to $1,000+ per infusion session — and the requirement for a clinical setting or mobile service.

Oral NMN supplements are far more accessible and affordable — typically $30 to $100 per month — but deliver smaller NAD+ increases and rely on the body conversion pathways, which may be less efficient in older individuals. The clinical evidence for oral NMN is growing but remains less established than the decades of basic science behind NAD+ biology itself.

Animal studies on NAD+ precursors have produced striking results — NMN and NR supplementation has reversed some aging markers in mice. Human clinical trials are still in earlier stages, and the translation of animal findings to human outcomes is not guaranteed.

The most honest summary of current evidence is that NAD+ biology is scientifically well-grounded, that precursor supplementation does raise NAD+ levels in humans, and that the clinical benefits of those increases are still being characterized in randomized controlled trials. The field is moving quickly, and the picture will look different in two to three years than it does today.