# NAD+ Dosage in the Research: Doses Used in Precursor Studies

> NAD+ dosage as study context only: the NMN and NR doses used in human trials, the routes studied, and how long infused versus supplemented NAD+ persists.

Reported as study parameters — what was administered, by which route, for how long. No dosing instructions are given.

## The short version

This page reports the NAD+ dosage figures that show up in published studies, and only as study context — it gives no instructions to take anything, and it is not medical advice. Almost every human number is a *precursor* dose, NMN or NR, because oral NAD+ itself is poorly absorbed (a precursor is a building block the body converts into NAD+). The pattern across trials is consistent: more precursor, more blood NAD+. Below are the doses, the routes researchers used, and how long NAD+ actually persists once it is infused versus supplemented — each tied to the study that measured it. Read every figure here as "this is what an experiment administered," never as "this is what you should take."

## Doses used in NAD+ precursor studies

In human trials, NMN appeared at `250–900 mg/day` orally, with `250 mg/day` the most-replicated dose and up to `1200 mg/day` studied; `600 mg/day` was identified as optimal in the multicenter dose-ranging trial [3][1]. Nicotinamide riboside (NR) appeared commonly at `250–1000 mg/day` orally, with up to `3000 mg/day` tested for safety in a Parkinson's-disease study [4]. Nicotinamide (NAM) has been studied at `500 mg twice daily` for skin-cancer chemoprevention. For IV NAD+, reported wellness/clinical infusion protocols run roughly `250–1000 mg per session` over several hours, and a pharmacokinetic study used a continuous `3 µmol/min` infusion over six hours.

One pattern is worth noting: the doses span a wide range — from `100 mg/day` of NR at the low end to `3000 mg/day` at the high end — and the trials that pushed highest were generally *safety* studies asking whether a dose was tolerable, not efficacy studies claiming it worked better. The most-replicated efficacy doses sit far lower (`250 mg/day` NMN; a few hundred mg/day NR), which is why a bigger number on a label is not a stronger claim from the literature.

These are observed study parameters. Reporting that a trial administered `250 mg/day` of NMN is a description of that experiment — not a recommendation, and not a statement that any dose is safe or effective for any individual.

## How long does infused or supplemented NAD+ persist?

The two routes behave very differently. Infused NAD+ is cleared from plasma fast: a pilot study found near-complete plasma removal within roughly the first two hours of infusion, consistent with the in-vitro finding that extracellular NAD is degraded by surface ecto-enzymes before cells can take it up intact [12]. Oral precursors are the opposite — they are absorbed and raise *whole-blood* NAD+ over days to weeks, and that elevation is sustained through chronic dosing in 8–12-week trials (NR's 22%/51%/142% rise was maintained across the full eight weeks; NMN's rise held at days 30 and 60) [4][3]. So "how long does NAD+ last" depends entirely on whether you mean a rapidly-cleared infusion or a precursor regimen that shifts the steady-state blood NAD+ level.

## Why the numbers are precursor numbers

Read the dose figures above carefully and a pattern jumps out: nearly every human number is a *precursor* dose, not a dose of NAD+. That is not an accident of how trials were designed — it is forced by the biology. Intact NAD+ is a large, charged dinucleotide (`MW 663.43 Da`, `C21H27N7O14P2`) that cells do not freely import, and extracellular NAD is broken down by surface ecto-enzymes before any uptake [12]. So a study that wants to raise the NAD+ pool administers a building block — NMN at `250–900 mg/day` [1][3] or NR at `100–3000 mg/day` [4] — that the body converts into NAD+ through the salvage and related pathways. When you see "NAD+ dosage" discussed anywhere, the honest translation is usually "precursor dosage," and this digest keeps that translation explicit rather than letting an NMN figure masquerade as an NAD+ figure.

## Routes studied, and how they differ

Oral capsules and powders of NMN, NR and nicotinamide carry the bulk of the controlled human evidence [1][3][4]. Intravenous NAD+ infusion is used in wellness settings but has limited controlled data — mostly pilot and retrospective — and is rapidly cleared from plasma [12]. Subcutaneous and intramuscular NAD+ injection is compounded with minimal peer-reviewed pharmacokinetic data. Sublingual, intranasal, topical and transdermal patch products are marketed with little controlled evidence; the human pharmacokinetic data cited here are for oral precursors, not patches.

The route choice changes the pharmacokinetics completely. An oral precursor is absorbed, metabolized into NAD+, and shifts the steady-state *whole-blood* NAD+ level over days and weeks [4][3]. An IV NAD+ infusion delivers the coenzyme directly into plasma but is then cleared within roughly two hours [12], so it produces a transient spike rather than a sustained shift — and because extracellular NAD is degraded at the cell surface, even that plasma NAD+ is not taken up intact [12]. These are mechanistically different interventions that happen to share the letters "NAD," which is exactly why the literature treats the oral-precursor evidence and the IV evidence as separate bodies of work.

## Stability and the compounded-injectable risk

Stability is a practical footnote with a sharp edge. NAD+ and NMN are hygroscopic and degrade with heat and moisture, and reconstituted injectable NAD+ should be kept cold and protected from light. Compounded injectables carry contamination risk that oral capsules do not: an FDA Class I recall — the agency's most serious category — has been issued for a compounded NAD+ injection over elevated bacterial endotoxin. That recall is a documented quality event tied to the compounding of an injectable product, not an approved medicine with a manufacturing standard behind it. It is the single clearest reason the oral-versus-injectable distinction is not merely pharmacological but a matter of product quality, and why this page reports the IV route with that caveat attached every time.

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A multi-channel instrument reading of the NAD+ literature — the redox coenzyme on one channel, its NMN and NR precursors on another, the human-trial signal logged apart from the rapidly-cleared IV noise — calibrated to the published studies, with no clinic behind the panel and nothing here dosed, infused, prescribed, or sold.