Beware melatonin supplements – their labels lie

The Pediatric Insider

© 2017 Roy Benaroch, MD

About 36 billion dollars will be spent on vitamins and nutritional supplements in the US this year. It is a huge industry, with big advertising and PR budgets. Maybe it’s time for the manufacturers to spend a little money figuring out how to deliver honest and accurate products.

Tests on a variety of supplements have already shown that most of them are contaminated – many with toxic metals, like lead and arsenic. And a new study of one of the most popular supplements, melatonin, shows that most of the brands available have doses far different from what’s on the label.

Researchers in Canada purchased 31 melatonin products from stores in Guelph, Ontario (IKR! I didn’t know there was a Guelph in Ontario!) They analyzed the content of tablets, liquids, and chewables, and found that few of the products contained their labeled dose. 71% of the products were off by more than 10%, with the actual content of melatonin ranging from 17% to 478% of the labeled dose. There was a huge variability even among the same brand, with different bottles varying by 465% in content. Their research was published in the February, 2017 edition of The Journal of Clinical Sleep Medicine.

Potentially worse: 26% of the samples contained serotonin, a contaminant that can cause serious side effects, especially when combined with a variety of medications.

Though these samples were purchased in Canada, there’s no reason to think melatonin products sold in the US would be any more consistent. Neither country has any laws or standards established to regulate, test, or ensure the quality of “dietary supplements” including melatonin, vitamins, or any so-called “natural” or “herbal” products. In other words, there’s no reason to think that you’re getting what you think you’re getting.

There are some voluntary industry standards, and at least that’s a start. The press release about the melatonin study suggested that consumers from the USA look for a “USP Verified” logo certification from the “United States Pharmacopeial Convention.” I could only find one brand on the USP website of melatonin that’s been certified – “NatureMade” (scroll down the bottom, here. Oddly, the Amazon entries for these products don’t indicate that they’re USP certified.)

Many people purchase herbs and supplements for a variety of reasons – and there are some good clinical studies showing that some of them may help (many others, not so much.) But it doesn’t matter what the studies show if what you’re taking isn’t what’s labeled on the bottle. If the supplement manufacturers want to genuinely help people stay healthy, they need deliver a consistent and reliable product. Otherwise, it’s just smoke, mirrors, and empty promises that might make you sick.

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8 Comments on “Beware melatonin supplements – their labels lie”

  1. Mark Says:

    I don’t see any way this gets solved without government regulations. In the regulation-free “wild west” we currently have, are there any supplement companies who have been proven trustworthy?


  2. Jack Says:

    478%!? That’s insane. Thanks, will definitely look for that stamp on the labels going forward.


  3. Dr. Roy Says:

    Mark, the USP mark is thought to be very reliable — they have stringent qualifications. Only 1 company has USP certified melatonin, “NatureMade.” I can’t vouch for their other products.

    There’s also an independent, well-regarded website called “” that claims to stringently test supplements. It’s a pay site. I have no experience with them, but might join for a year just to see what they’re up to.


  4. Dr. Roy Says:

    Jack, yeah, the numbers are all over the place for this stuff. And I think it would probably be the same for other supplements. There’s just no oversight, and apparently few of the people who buy these things seems to care whether they objectively work or objectively contain their purported ingredients.


  5. Mark Says:

    That USP site lists only a couple brands that have done USP certification and not a wide variety of supplement types (mostly it is standard vitamins and minerals that are on the USP list), so I hope that this is not the only meaningful certification for supplements. What I have heard is that if a supplement is manufactured in the U.S., it’s probably good. Most supplements are manufactured in China though, so in practice you’re looking for a U.S.-based supplement company that does their own quality assurance testing on what they receive from China in order to verify the ingredients. My understanding is that cGMP on the label is the best indicator of this. I’ve been looking for companies that have statements like this on their website: At times, I have asked companies to provide me with copies of their independent lab assessments of the supplements. So what do you think? Is cGMP a strong enough statement of quality? Here’s the FDA site about the regulation:


  6. Dr. Roy Says:

    Mark, I believe the FDA doesn’t prospectively or proactively monitor any manufacturing practices, and only becomes involved with these products AFTER marketing, and only if harm has been demonstrated (see: ephedra). GMPs are found throughout many industries, but is there any enforcement? What if they’re not followed? That FDA page didn’t mention any sanctions or any way for these standards to be measured or enforced.


  7. Mark Says:

    I’m not entirely clear on how the FDA’s ability to measure and enforce GMPs in supplements differs from their ability to measure and enforce GMPs in the pharmaceutical drug industry or any food items we consume. I understand there are big differences in terms of proving what the product does and proving that the product is sufficiently safe, but I don’t understand the differences when it comes to ensuring that the bottle contains what it says on the label. Seems like ultimately, GMP regulation is the way the FDA deals with companies in any industry who aren’t testing for adulterated products. Here are some of the “sternly worded letters” they’ve sent out to prescription drug companies, and from what I can tell, this sort of facility monitoring and resulting “slap on the wrist” is the same as what they do with supplement companies (and in fact, some of the letters reference both drugs and supplements). So what specific measurement/enforcement actions are taken against drug companies to ensure the medicine you buy at the pharmacy contains exactly what it says it does?


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