Melatonin users should prepare for bottle shock
Researchers find 71 per cent of the products they tested did not match label claims
Researchers have measured levels of melatonin in a number of over-thecounter supplements sold in Canada and found amounts of the hormone can vary dramatically from what’s listed on the products’ labels.
Melatonin is produced in the brain and occurs naturally in small quantities in some meats, grains, fruits and vegetables. Supplements containing melatonin are often taken by people in a bid to overcome sleep problems.
A study by the University of Guelph, published this week in the Journal of Clinical Sleep Medicine, tested 30 melatonin supplements produced under 16 brand names and sold in grocery and drug stores.
The researchers found 71 per cent of the products — which were not identified by name — did not meet label claims. Higher-than-listed amounts of melatonin ranged between 12 and 25 per cent on average, but some had nearly five times the hormone they were said to contain.
One chewable tablet, for instance, contained more than eight milligrams of melatonin, a 478 per cent increase over the 1.5 milligrams shown on its packaging.
Others were found to have melatonin levels lower than what was listed.
One supplement, which also contained lavender, camomile and lemon balm, had 83 per cent less melatonin than the three milligrams each capsule was said to contain.
Principal investigator Praveen Saxena, a professor in the Ontario university’s department of plant agriculture, said amounts of melatonin in the supplements tested sometimes also varied from lot to lot within the same product line.
Of even more concern was that about a quarter of the supplements also contained serotonin, a neurotransmitter involved in mood regulation and nerve impulse transmission, which was not included in the products’ ingredients lists and could cause adverse effects.
“Millions of people use melatonin for a variety of purposes, including as a sleep aid and for jet lag,” Saxena said. “These products are often selfprescribed, so it’s important that labels are accurate and the products free from contaminants.”
Saxena said melatonin is an unstable molecule and in supplement form may be affected by environmental conditions.
“We wanted to help bring the point forward and not point fingers because we don’t really believe that it is intentional,” he said.
“I think it’s more like this is a finding that can help consumers and help manufacturers improve production quality.”