NAD+ and the prescription question
A prescription sounds reassuring. The ingredient, the route and the measured result deserve equally close attention.
What is NAD+?
NAD+ is nicotinamide adenine dinucleotide, a coenzyme—a small molecule that helps enzymes do their work. Every cell makes it. It carries electrons through the reactions that release energy from food, and other enzymes consume it during DNA repair and cellular signalling. The review of NAD+ metabolism and ageing describes both jobs. That is a remarkable amount of responsibility for something so small.
The replacement story sounds tidy: NAD+ falls with age, so add more. The neatness initially persuaded me. The human evidence collected in the 2025 review makes the picture more interesting: tissue measurements are scarce, and clinical benefits have been limited. I’ve become less persuaded by tidy replacement stories than by the individual experiments.
NAD supplement ingredients
An NAD supplement often contains NMN or nicotinamide riboside, usually shortened to NR. These are precursors, ingredients the body can turn into NAD+. Niacin and nicotinamide also feed its synthesis. The different routes for making and recycling NAD+ explain why the small print on a supplement matters.
The molecule itself behaves less like a parcel delivered intact than I expected. In human skin cells grown in a dish, extracellular NAD broke into smaller substances before uptake; adenosine was the main breakdown product taken into the cells. That experiment has a very specific address: a cell culture. It supplies a reason to study uptake carefully, while the clinical questions need experiments in people.
For the ingredient comparison, start with NMN and NR in human trials. For amounts attached to particular experiments, there is a study dosage register.
The NR blood results
A trial in otherwise healthy overweight adults gave oral NR at 100, 300, or 1000 mg/day for 8 weeks. Whole-blood NAD+ rose 22%, 51%, and 142%, respectively. That precision earns my confidence: a named ingredient, a named population, a measured change.
Claims about energy or longer life require their own results. The 2023 review of human supplementation trials found consistent increases in NAD+ metabolites alongside mostly unchanged functional outcomes. The research page follows the promising exceptions as well as that larger pattern.
Prescription NAD+ and the IV route
Patient-specific injectable NAD+ is pharmacy-compounded on a licensed clinician’s prescription. Compounded NAD+ has no FDA approval, and no NAD+ treatment has FDA approval for an illness. Oral supplements and compounded infusions come with different evidence and different risks.
A prescription answers a question about individual clinical authorization. The question of benefit still needs a study that measures it. IV NAD therapy has a much thinner controlled record than the oral precursors; NAD+ side effects includes infusion symptoms, contamination and the FDA Class I recall. Those particulars deserve to travel with the word “prescribed”.
Ageing claims
The CD38 experiment in ageing mice offers a compelling mechanism: mice lacking this NAD-consuming enzyme preserved NAD+ and mitochondrial function as they aged. The enthusiasm around that experiment seems understandable. The later review of human ageing trials found limited clinical efficacy and sparse tissue data. Visible rejuvenation and longer human life remain outside what the cited trials establish.
The part I’d like settled is whether a sustained change in the relevant human tissue produces a durable improvement in function. A blood result gives that experiment a starting point. It still leaves plenty to discover.