NAD+ Dosage in the Research: The Doses Studied, and How They Clear

The gist

This page reports the doses that appeared in studies — nothing more. Because NAD+ (the cell's energy-handling helper molecule) is poorly absorbed whole, the doses studied are mostly of precursors (the building blocks the body turns into NAD+): NMN and NR, measured in milligrams per day. There is no established "correct" human dose, no validated timing, and this is not advice to take anything. Below, every figure is tied to the trial that used it, so you can see exactly what was tested and in whom.

Doses Used in the Research Literature

Across the controlled human literature, oral precursor doses cluster in a few ranges. NMN was studied at 250 mg/day (the muscle-insulin-sensitivity trial in postmenopausal women) ^[1] and at 300, 600, and 900 mg/day for 60 days in a multicenter RCT, where 600 mg/day was identified as the optimal dose ^[3]; doses up to 1200 mg have been reviewed ^[15]. NR was studied at 100, 300, and 1000 mg/day for 8 weeks ^[4], with up to 3000 mg/day tested for safety in a Parkinson's disease trial and reviewed in the 250-3000 mg range ^[15]. Nicotinamide at 500 mg twice daily has been studied for skin-cancer chemoprevention.

For the IV route, reported infusion protocols fall around 250-1000 mg per session over several hours; one pharmacokinetic study used a continuous infusion over six hours. These are the doses that were administered in cited research — reported here as research context, with no recommendation to use any product or dose.

Clearance and Pharmacokinetics in the Studies

NAD+ itself is not freely taken up intact by most cells, and infused IV NAD+ is rapidly cleared from plasma — a pilot study found near-complete plasma removal within roughly the first two hours of infusion. That rapid clearance is one reason the IV route's evidence is weak: much of the infused dose appears to be metabolized extracellularly rather than delivered to cells intact.

Oral precursors behave differently. They are absorbed and raise whole-blood NAD+ over days to weeks, with the elevation persisting through chronic dosing in 8-12 week trials ^[3][4]. Blood NAD+ itself returns toward baseline within weeks of stopping. NAD+ and NMN are also hygroscopic and degrade with heat and moisture, and compounded injectables carry contamination risk, as the Class I endotoxin recall demonstrated.

Routes Studied

The cited literature covers several routes with very different evidence weights. Oral capsules and powders of NMN, NR, and nicotinamide carry the bulk of controlled human data ^[3][4]. Intravenous NAD+ infusion is used in wellness settings but has only limited, mostly pilot or retrospective data. Subcutaneous and intramuscular NAD+ injection is compounded with minimal peer-reviewed pharmacokinetic data, and sublingual, intranasal, topical, and transdermal-patch formats are marketed with little controlled evidence. Topical nicotinamide is the exception with clinical skin data ^[13].

The route also decides what the dose number means. A 600 mg oral NMN dose ^[3] and a 600 mg IV NAD+ dose are not comparable quantities of "NAD+" reaching cells: the oral dose is a precursor processed through absorption and enzymatic conversion, while the IV dose is the intact coenzyme that is largely cleared from plasma before it can be taken up. Reading a dose without its route is how the NAD+-versus-precursor distinction gets lost.

Stability and Product-Quality Notes

Two practical facts about the materials recur in the literature. First, NAD+ and NMN are hygroscopic — they pull in water — and degrade with heat and moisture, so reconstituted injectable NAD+ is kept cold and protected from light. Second, supplement-grade products vary widely in purity and actual content, and third-party testing is not guaranteed; the dose on a label is not always the dose in the capsule.

The sharpest quality signal in the record is on the injectable side: a compounded injectable NAD+ product was subject to an FDA Class I recall for elevated bacterial endotoxin contamination. A Class I recall is the most serious category, reserved for products that may cause serious harm. This is reported as documented context for reading the IV-NAD+ literature, not as guidance about any specific product, and this site recommends no product or dose.