A new study published in the Journal of Clinical Sleep Medicine indicates that the amount of melatonin listed on a dietary supplement label may not always match up to what’s actually inside the bottle.

Melatonin is a natural hormone that helps regulate the daily cycle of sleep and wakefulness. It is available as a dietary supplement to help treat and prevent sleep-related disorders such as insomnia or jet lag.  Data from the National Center for Health Statistics of the National Institutes of Health show that the use of melatonin supplements by adults in the U.S. more than doubled from 0.6% in 2007 to 1.3% in 2012, with an estimated 3.065 million adults reporting that they had taken melatonin during the past 30 days. 

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Given its popularity and the fact that supplements are not subject to the same scrutiny as pharmaceuticals in the U.S., researchers aimed to determine the variability in the amount of melatonin content in 30 commercial supplements comprising different brands and formulations.

Using ultraperformance liquid chromatography with electrochemical detection, they found that  in more than 71% of the samples, the melatonin content did not meet the label within a 10% margin of the label’s claim. The actual melatonin content ranged from –83% to +478% than the concentration declared on the label. The lot-to-lot variability within a particular product was also found to differ by as much as 465%. This variability found among the supplements did not appear to be correlated with manufacturer or product type. 

In addition, the presence of serotonin (5-hydroxytryptamine) was identified in 8 (26%) of the supplements at level of 1 to 75μg.

“Millions of people use melatonin for a variety of purposes, including as a sleep aid,” said lead author Lauren A.E. Erland. “It is important that clinicians and patients have confidence in the quality of supplements used in the treatment of sleep disorders.”

The authors suggest increased controls by manufacturers to ensure that supplements meet the label claim and are free from contaminants. In the meantime, consumers should look for the “USP Verified” mark, which indicates that the formulation meets the requirements of the U.S. Pharmacopeial Convention.

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