Melatonin Natural Health Products and Supplements: Presence of Serotonin and Significant Variability of Melatonin Content.
Level 5 - mechanism / opinion, no new human data
Bench analytical chemistry study of commercial products without human participants (non-clinical study by design analogy)
PubMed 27855744 · doi:10.5664/jcsm.6462
What was done
The authors evaluated 31 commercial melatonin supplements across various brands and formulations. Melatonin and serotonin concentrations were quantified using ultraperformance liquid chromatography with electrochemical detection, with serotonin presence confirmed by ultraperformance liquid chromatography with mass spectrometry.
What was found
Melatonin content ranged from -83% to +478% of the labeled amount, with over 71% of supplements failing to meet label claims within a 10% margin. Lot-to-lot variability within the same product reached up to 465%, with no correlation to brand or product form. In addition, unlisted serotonin was detected in 8 of 31 supplements (26%) at levels ranging from 1 to 75 µg.
Why it matters
Over-the-counter melatonin supplements exhibit substantial dose inaccuracies and can contain active contaminants like serotonin, creating clinical unpredictability and safety risks for individuals treating sleep disorders.
Limits
The sample was limited to 31 products, and the abstract does not specify the geographic market or sourcing methodology. The study was strictly an analytical laboratory assessment and did not measure human clinical outcomes, bioavailability, or adverse events.
Cited by
- supports Commercial melatonin supplements can vary in their actual melatonin content by up to 85% compared to the stated label dose.