What Is NAD+? The Molecule and the Vial

The left column is why the compound sounds familiar and safe. The right column is what actually gets bought. Nothing in the left column certifies the right one: a molecule the body already handles can still arrive in a vial whose contents nobody has measured, at a concentration nobody wrote down.

The rest of this site works with vials holding 5 or 10 mg, where a draw is a small fraction of a syringe barrel. NAD+ inverts that. Here is the same conversion chain run at both scales, on a U-100 syringe where one unit is 0.01 mL.

Read the fourth column. On a typical peptide vial a single unit carries micrograms, so the syringe scale is far finer than the amounts in question and rounding to the nearest graduation costs almost nothing. On a 1000 mg NAD+ vial at 100 mg per mL, a single unit carries a whole milligram. One graduation misread is a milligram gone, which on a peptide vial would be the entire contents several times over.

The last column matters for a different reason. Barrel capacity stops being theoretical. At 50 mg per mL an amount of 50 mg fills the barrel completely, so anything larger needs more than one draw or a larger syringe. That constraint never arises at 2.5 mg per mL, and it catches people who carried habits across from a 5 mg vial.

There is a second scale effect, and it is the one most often missed. Concentration is usually computed as labelled mass divided by water added. That treats the powder as occupying no space. At 5 mg the approximation is harmless. At 1000 mg it is not.

Take an assumed solid density of 1.5 g per mL. The density is an assumed input, stated here so the arithmetic can run, not a measured property of any particular product. One gram of solid at that density occupies about 0.67 mL. Add 10 mL of water and the final volume is roughly 10.67 mL, not 10. The true concentration is 1000 divided by 10.67, about 93.7 mg per mL, where the label arithmetic said 100. That is an overstatement of roughly one part in fifteen, and it runs through every draw taken from that vial.

Run the same assumption on a 5 mg peptide vial and the solid occupies about 0.003 mL against 2 mL of water, an effect near one part in six hundred. Invisible, correctly ignored.

The fix is a change of method rather than a correction factor. If the container is graduated, reconstitute to a final volume and read the mark, rather than adding a measured volume of water and assuming the total. Then the denominator is observed instead of inferred, and the assumed density drops out of the calculation entirely.

The literature attached to this molecule is enormous, and it is mostly not about the thing in the vial. The bulk of the interventional human work studies NAD precursors, principally nicotinamide riboside and nicotinamide mononucleotide, given orally in tablet or capsule form. Those are the trials in humans. Injected NAD+ is a different intervention with a much thinner record, and a claim sourced from a precursor trial does not carry over to it without saying so.

That distinction has to survive into every sentence. Writing that NAD+ has been studied extensively in humans is misleading when the studies were of an oral precursor. Naming the intervention costs four words and preserves the whole meaning.

The natural next question is whether an oral precursor amount can be converted into an injected NAD+ amount. Write it out and the answer becomes visible without any biology.

An equivalent injected mass would be the oral precursor mass multiplied by the fraction absorbed from the gut, multiplied by the fraction converted onward into NAD+, multiplied by whatever term relates an oral route to an injected one. That is one known quantity and three unknowns. No published figure is cited here for any of the three, because none is being asserted.

A calculator will still produce an answer if someone guesses those fractions, and the answer will look as precise as every other number on this page. It is not the same kind of number. The conversions in the tables above are definitional: a unit is a volume, a concentration is a ratio, and division cannot be wrong about them. The precursor conversion is an empirical claim wearing arithmetic as a costume.

Per milligram is the wrong unit here. On a 500 mg vial it produces a figure with too many leading zeros to compare at a glance, so quote per 100 mg instead: for a vial priced at P, that is P divided by five. For a 1000 mg vial at price Q, it is Q divided by ten. The larger vial is the better value per 100 mg only when Q is less than twice P, which is worth checking rather than assuming.

The comparison also has to survive the water clock. Bacteriostatic water is generally treated as giving a preserved solution roughly four weeks of use. Suppose a 1000 mg vial at 100 mg per mL is drawn in 50 mg portions, which is 20 draws, and take an every other day interval purely as an arithmetic input rather than as any suggested pattern. Fourteen of those draws fall inside a 28 day window and six do not. Seven hundred milligrams gets used, so the real figure is Q divided by seven per used 100 mg, not Q divided by ten. Buying the larger container improved the shelf price and worsened the delivered one.