NAD+ dosage in the research — the figures, and why they are not a recommendation

Read this first

There is no approved NAD+ dose for any condition, so nothing here is guidance. What follows is a record of what investigators gave to study participants — the milligrams, the routes, the durations — reported so a careful reader can see the actual numbers behind the headlines. "NAD+" by mouth is mostly precursors (NMN and NR, the building blocks cells turn into NAD+); the intravenous route delivers NAD+ itself but clears from the blood fast. Every figure below is research framing: studied at X, in Y people, for Z weeks — not a dose for anyone to take.

Doses used in the research (and why they are not a recommendation)

The controlled human studies cluster into a few ranges. For NMN, oral doses of 250-900 mg/day appear across human RCTs; 250 mg/day is the most-replicated dose, and a multicenter trial flagged 600 mg/day as optimal across its 300-900 mg/day arms ^[3]. The 250 mg/day dose is the one that improved muscle insulin sensitivity over 10 weeks in prediabetic women ^[1]. For nicotinamide riboside (NR), 250-1000 mg/day is common, with 1000 mg/day the dose used in the eight-week dose-response and the six-week crossover trials ^[4][6]; higher doses up to 3000 mg/day have been tested for safety. For IV NAD+, reported protocols run roughly 250-1000 mg per session over several hours; one pharmacokinetic study infused 750 mg over six hours ^[8].

These figures describe what researchers administered in specific populations. They are not titration schedules and not a recommendation to dose.

Why precursors, not NAD+, are the oral approach

NAD+ is a 663-dalton dinucleotide carrying two phosphate charges, which is precisely why it is not freely taken up intact by most cells and not an effective oral product on its own ^[14]. The oral approach that the trials actually use is a precursor (a smaller building block the body converts into NAD+ — chiefly NMN and NR). NR is converted to NMN by NRK kinases and then to NAD+; NMN sits one step from NAD+ ^[5]. This is the mechanistic reason the dosing literature is overwhelmingly a precursor literature.

How long NAD+ and its precursors persist

The half-life picture splits sharply by route. Infused NAD+ is rapidly cleared from plasma: a six-hour IV pilot found plasma NAD+ stayed undetectable for roughly the first two hours before rising, with the dose instead showing up as elevated urinary methylated nicotinamide metabolites — evidence of extensive extracellular metabolism rather than a durable plasma pool ^[8]. Oral precursors work on a slower clock: they are absorbed and raise whole-blood NAD+ over days to weeks, with the elevation sustained through chronic dosing in six-to-twelve-week trials ^[4][6]. One NMN study found blood NAD+ returned toward baseline within about four weeks of stopping. The contrast is the practical core of the route question: IV spikes and clears; oral precursors build and hold.

Routes studied, ranked by evidence weight

Oral capsules and powders of NMN, NR, and nicotinamide carry the bulk of the controlled human evidence ^[3][4][6][7]. Intravenous NAD+ infusion is used in wellness settings but rests on limited controlled data — mostly pilot and retrospective studies ^[8]. Subcutaneous and intramuscular NAD+ injection is compounded with minimal peer-reviewed pharmacokinetic data. Sublingual, intranasal, topical, and transdermal forms are marketed with little controlled evidence behind them. A note on handling, since it bears on product quality: NAD+ and NMN are hygroscopic and degrade with heat and moisture, and compounded injectables carry contamination risk — the FDA has issued a Class I recall of a compounded NAD+ injection over elevated endotoxin. The injectable route is covered in full under IV NAD+ and injectable routes.

How much NAD should I take?

There is no approved dose. Trials have used oral NMN at 250-900 mg/day, with 600 mg/day flagged as optimal in one multicenter RCT ^[3], and oral NR at 250-3000 mg/day ^[4]. These figures describe what researchers administered, not guidance for use.