Over the last few years, melatonin supplements have grown in popularity as a way to help people, including children, improve their sleep habits. But a new study published in JAMA found that almost 90% of melatonin gummies have significantly higher quantities of the hormone than advertised, which could negatively affect consumers' health.

Melatonin gummies may not be as advertised

Melatonin is a hormone produced in response to darkness that can help regulate the body's sleep cycle. It is widely sold as a dietary supplement to help people sleep more easily. According to a 2022 study, melatonin use among U.S. adults increased by more than five times between 1999 and 2018.

As a dietary supplement, melatonin products are not reviewed by FDA before they enter the market. Although melatonin is generally considered safe, there is little information about the highest dose people can safely consume. Taking too much melatonin can lead to breathing difficulties, vomiting, and excessive sleepiness.

Children in particular may be susceptible to adverse outcomes from high doses of melatonin. In a recent CDC report, researchers found that the number of calls to U.S. Poison Control Centers about melatonin ingestion among children jumped 530% between 2012 and 2021. Overall, these calls were associated with 27,795 ED and clinic visits, 4,097 hospitalizations, 287 ICU admissions, and two deaths.

With this rise in pediatric melatonin ingestions, researchers decided to test the melatonin content in commonly available gummy dietary supplements. For the study, the researchers used the NIH Dietary Supplement Label Database to identify 30 unique melatonin gummy brands, which were marketed to both adults and children.

Of these 30 brands, four were unavailable to purchase, and one did not include "melatonin" in its label, so 25 products were included in the final analysis. To determine the contents of each gummy product, the researchers reconstituted the gummies in methanol and a mixture of acetonitrile-methanol before assessing their levels of melatonin, cannabidiol (CBD), and serotonin. Serotonin was included because it had previously been reported as a potential contaminant in melatonin products.

Overall, the researchers found that 22 out of the 25 products (88%) were inaccurately labeled, with one product containing only CBD and no melatonin. In the products with melatonin, the actual amount included ranged between 74% to 347% of the labeled quantity. Only three products had quantities within 10% of what was specified in their labels.

"I can't be assured the supplements my patients will see on store shelves are going to be accurately labeled," said Pieter Cohen, an associate professor at Harvard Medical School who led the study.

Should FDA do more to regulate dietary supplements?

According to Stephen Ostroff, a former FDA official who served as both acting commissioner and deputy commissioner of the agency's food program, the study is the "perfect example of why the FDA needs to do a better job overseeing dietary supplements."

Although Cohen acknowledged that FDA's current legal authority to regulate supplements is weak, he also argued that the agency has not done enough to enforce its current regulations, which may result in products of questionable quality being put on the market.

"The regulatory framework for supplements is broken," Cohen said. "The manufacturers are not complying with the law, and the FDA is not enforcing the law. So what that means is that we have a lot of poor-quality products out there."

For its part, FDA said it would "review the findings of the paper" and that it "takes product quality concerns, including under- or over-potent products, seriously." However, the agency also emphasized that "does not have the authority to approve dietary supplements before they are marketed, and firms have the primary responsibility to make sure their products are not adulterated or misbranded before they are distributed."

Representatives of the dietary supplements industry have also defended the safety of these products. According to Steve Mister, CEO of the Council for Responsible Nutrition, "supplement companies go to great lengths" to ensure the safety of their products, as well as the accuracy of their labels.

How to protect children from high doses of melatonin

Because high doses of melatonin may negatively impact children, health experts recommend keeping these supplements out of their reach so that they won't accidentally ingest them, especially the gummy versions.

"What worries me about things being put into gummy form … is if you get a hold of that and you're a little kid, you're going to chow down on it," said Sarah Ash Combs, an emergency medicine physician at Children's National Hospital.

Cora College Bruener, a pediatrician at Seattle Children's Hospital, recommends parents speak with a pediatrician about how to help their child sleep and develop good sleep hygiene habits before they try a supplement. Parents should also speak to a pediatrician before giving a supplement to their children.

For people who want to use melatonin, whether for themselves or their children, experts recommend buying supplements that have been assessed by a third-party, independent entity, such as U.S. Pharmacopeia, to ensure their quality and ingredient accuracy.

"Melatonin is not equivalent to a warm glass of milk," Cohen said. "Melatonin should be treated by what it truly is, a medication. Just as parents would not casually give Benadryl to children to help them go to sleep, the same approach should be taken toward melatonin." (Florko, STAT, 4/25; George, MedPage Today, 4/25; Hassanein, USA Today, 4/26; Whyte, Wall Street Journal, 4/25; Sforza, The Hill, 4/26)