NAD+ dosing — commonly cited amounts and routes

"How much NAD+" has no single answer because three distinct things are sold under the same banner: oral precursors that cells convert into NAD+ (nicotinamide riboside, nicotinamide mononucleotide), direct NAD+ given by injection, and direct NAD+ given by slow intravenous infusion. Their doses are not interchangeable, and only one of the three has a randomized dose attached to it.

In the most-cited human trial — a 2×6-week randomized, double-blind, placebo-controlled crossover study in healthy middle-aged and older adults, 30 randomized and 24 completing — participants took 500 mg nicotinamide riboside twice daily, 1,000 mg/day (Martens et al., Nature Communications, 2018; PMID 29599478). That regimen raised NAD+ in peripheral blood mononuclear cells by roughly 60% versus placebo and was well tolerated with no serious adverse events.

Two things about this number matter for anyone reading dosing claims. It is an oral precursor dose, not an NAD+ dose. And what it demonstrably achieved was a change in a blood biomarker; the physiological readouts in that trial were exploratory and did not reach significance after correction.

The one published intravenous NAD+ regimen in humans comes from a pilot study in Frontiers in Aging Neuroscience (PMID 31572171): a 6-hour infusion at 3 µmol/min, run because no data existed on the fate of directly infused NAD+ in people. Plasma NAD+ and its metabolites showed no change until after 2 hours; by 6 hours urinary excretion of NAD+ and methylnicotinamide had increased.

Two features of that result are relevant to any IV dosing discussion. The infusion was deliberately slow and long. And a substantial fraction of what went in came out in urine — an argument that infusing more, faster, is not straightforwardly delivering more to cells.

Reported figures, which vary widely and are not medically established:

• Subcutaneous injection of roughly 50–100 mg per administration is a commonly cited community figure.
• IV clinics commonly describe larger session totals delivered slowly over several hours.
• Oral precursor products are dosed separately again, typically in the few-hundred-milligram range per capsule.

None of these trace to a controlled trial. Because the body regulates NAD+ synthesis and clears excess, more input does not translate linearly into more usable NAD+ — which is one reason a larger number is not obviously a stronger intervention.

For most compounds, dose and schedule cover the question. For IV NAD+, the rate is a third variable with practical consequences: the flushing, chest tightness, nausea, and cramping described with infusion are consistently reported to ease when the drip is slowed, which is why clinic protocols emphasize slow administration. The published pharmacokinetic protocol above ran over six hours.

For injectable powder, the delivered amount is set by reconstitution — the substance in the vial relative to the diluent volume added — and syringe units measure volume rather than milligrams. Oral forms are subject to digestion and first-pass metabolism, which is a large part of why the marketed rationale for parenteral routes exists at all.

NAD+ is not an FDA-approved drug for any indication, so no labeled dose exists to anchor to, and NAD+ appears on FDA lists of substances raising concerns for compounding. Intravenous administration adds sterile technique, infusion pacing, and monitoring to the picture — none of which a calculator substitutes for. The field's own synthesis in Nature Reviews Molecular Cell Biology (NAD+ metabolism and its roles in cellular processes during ageing) states that much remains unknown about whether NAD+ repletion is safe and beneficial in ageing humans, which is the appropriate backdrop to any number on this page.