Testing the amount of nicotinamide mononucleotide and urolithin A as compared to the label claim

This is the study that explains why a printed NMN dose is not the same thing as a delivered NMN dose — and it is the single most important quality paper for anyone comparing NMN products on milligrams alone.

Researchers at the National University of Singapore bought eighteen NMN supplements and five urolithin A supplements online, in pharmacies and direct from manufacturers. A researcher outside the analysis team stripped the branding and renumbered them, so the laboratory measured blind. Each product was quantified five times using a mass-spectrometry method built and validated specifically for the job, and each capsule, tablet, sachet or softgel was also physically weighed with and without its shell.

The results ranged from plus 28.6 percent to minus 100 percent against the label. Three NMN products contained no detectable NMN at all. One capsule labelled 500 mg contained 168 mg. Another labelled 250 mg contained none. At the other end, four bulk powders labelled 1,000 mg measured within roughly 3 percent of claim, and one measured 992 mg against an adjusted claim of 990 mg.

The pattern is not random. The products that came closest to claim were straightforward powders from suppliers, several of which supply other supplement companies. The worst failures were capsules and liposomal formats, where more processing sits between the raw ingredient and the dose. The authors also note a separate ChromaDex analysis of 22 NMN consumer products in which 14 contained less than 1 percent of the claimed amount and three contained none — with only one product overlapping between the two investigations, and that one yielding similar results in both.

For a buyer, the practical conclusion is that a label number is a claim, not a measurement, and that independent batch testing is the only thing that converts one into the other.