RESEARCH DIGEST / DOSES STUDIED · NOT A RECOMMENDATION
NAD+ Doses Used in the Research — Reported, Not Recommended
The doses NMN and NR trials actually tested, the routes studied, and how NAD+ clears — logged as research figures. No human dosing guidance is given here.
Read this first
This page reports the NAD+ doses that appear in published studies — nothing more. It is not a dosing guide, not a protocol and not a recommendation to take anything. When you see a number like "NMN 250 mg/day," read it as "this is the dose a particular trial administered to a particular group," not "this is what to take." NAD+ itself is barely absorbed when swallowed, so the doses that matter in human research are almost all precursor doses (NMN, NR — the building blocks). We log what was tested, the routes researchers used, and how the molecule clears. No human dosing instructions appear anywhere on this site.
Doses Used in the Research (No Human Dosing Guidance)
When people search "NAD+ dosage," the honest answer is a list of studied precursor doses, not a target to hit. Across human randomized trials, NMN was studied at 250–900 mg/day orally, with 250 mg/day the most-replicated dose [1][9][10] and a dose-ranging trial testing 300, 600 and 900 mg/day over 60 days and identifying 600 mg/day as optimal [3]; up to 1200 mg/day has been studied. Nicotinamide riboside (NR) was commonly studied at 250–1000 mg/day, with a clean dose-response of 100/300/1000 mg/day over 8 weeks [4] and 1000 mg twice daily in heart failure [7]; it has been pushed to 3000 mg/day in a Parkinson's-disease safety study. IV NAD+ wellness protocols report roughly 250–1000 mg per session over several hours, and one pharmacokinetic study used a 3 µmol/min continuous infusion over 6 hours. Nicotinamide (NAM) has been studied at 500 mg twice daily for skin-cancer chemoprevention. Every figure here is a studied dose drawn from the literature — reported, not recommended.
Why Oral NAD+ Differs From a Precursor (NAD+ vs NMN)
The core of the NAD+ vs NMN question is bioavailability. NAD+ is a large, charged dinucleotide (663.43 Da), and it is not freely taken up intact by most cells — swallow plain "NAD+" and little reaches the inside of your cells as NAD+ [16]. Precursors solve this by being smaller, absorbable molecules the body assembles into NAD+ internally: NR and NMN enter the salvage machinery and lift the NAD+ pool from within [5]. That is why essentially every controlled human trial that successfully raised blood NAD+ used a precursor, not NAD+ itself [3][4][9]. So "NAD+ vs NMN" is not really a contest between two versions of the same supplement — it is the difference between a molecule that mostly cannot get in (oral NAD+) and a building block that can (NMN, NR). Some experts argue plain oral "NAD+" capsules are largely ineffective for this reason [16].
Routes studied
Four route families appear in the literature, with very different evidence behind them. Oral capsules and powder of NMN, NR and nicotinamide carry the bulk of controlled human evidence [3][4][9]. Intravenous NAD+ infusion is used in wellness clinics but has limited controlled data — mostly pilot and retrospective [17]. Subcutaneous / intramuscular NAD+ injection is compounded with minimal peer-reviewed pharmacokinetic data — the injectable and IV NAD+ risks are covered on the safety page. Sublingual, intranasal, topical and transdermal patches are marketed with little controlled evidence — except topical nicotinamide, which has clinical-trial support specifically for skin aging and pigmentation [13]. The weight of route evidence sits firmly on oral precursors; the further you get from that, the thinner the data.
Clearance and Persistence in the Research
There is no single NAD+ half life — how long NAD+ sticks around depends entirely on the route. Infused IV NAD+ is rapidly cleared from plasma — a pilot study found near-complete plasma removal within roughly the first two hours of infusion [17] — which is part of why IV's controlled evidence is weak. Oral precursors behave differently: they are absorbed and raise whole-blood NAD+ over days to weeks, and the elevation persists through chronic dosing in 8–12-week trials [4][9]. The effect is also reversible: after stopping NMN at 250 mg/day, blood NAD+ returned to baseline by about week 16 [9]. Single-dose pharmacokinetic work on oral NR showed dose-proportional rises in NR and NAD+ metabolites, with the metabolite NAAD reported with a half-life around 8 hours and used as a robust biomarker of pathway flux [8]. NMN and NAD+ are also hygroscopic and degrade with heat and moisture, and reconstituted injectable NAD+ should be kept cold and protected from light [16].
How much NAD should I take?
Studies used NMN 250–900 mg/day [1][3][9] and NR 100–3000 mg/day [4][7]. These are doses tested in research, not a dosing recommendation — no human dosing guidance is given here. Which dose, if any, is appropriate for a given person is a question for that person and a qualified clinician, not for this digest.