How Much Melatonin Is Really in That Supplement?

Supplementary melatonin is the fourth most popular natural product used by adults in the United States and the second most popular given to children.

But supplements like melatonin are not subject to the same quality controls as prescription medications. A new study of melatonin sold over-the-counter shows that information on the label often does not reflect the content of the product.

Melatonin content may differ from amount listed on labelSupplementary melatonin is the fourth most popular natural product used by adults in the United States and the second most popular natural product given to children. It can change the timing of sleep, ease jet lag, and help night owls shift to an earlier sleep schedule. Occasionally it’s used to correct a melatonin deficiency, or for insomnia (although for insomnia it’s unlikely to yield much benefit).

But supplements like melatonin are not subject to the same quality controls as prescription medications. A new study of melatonin sold over-the-counter shows that information on the label often does not reflect the content of the product. Here are the details:

Testing for Melatonin and Serotonin

The researchers tested the contents of 30 different melatonin supplements sold in Canada (likely similar to melatonin sold in the United States). Among them were products with 16 different brand names (the names were not published), in 5 different strengths, and in 7 different formulations, some containing herbal additives and others without. They wanted to see how closely the amount of melatonin listed on the label matched the melatonin content of the actual supplement.

They also screened for serotonin. Serotonin is a precursor of melatonin found in the herbal extracts with which commercial melatonin is often combined.

Variation in Melatonin Content

Holy cow! The actual melatonin content of the supplements varied quite a lot from the content listed on the labels. Some labels overstated the amount of melatonin contained in the product. The worst offender here was a capsule listed as containing 3 mg of melatonin that actually contained about 0.5 mg.

Other labels greatly underrepresented the amount of melatonin in the product. The worst offender here was a chewable tablet listed as containing 1.5 mg of melatonin that actually contained nearly 9 mg. (This is particularly concerning since chewable tablets are most often taken by children.)

Not only was the melatonin content of the product off by more than 10% of the listed content in about 71% of the products tested. As shocking as this may seem, the melatonin content varied widely from lot to lot of the same product. While the first lot of the chewable tablets cited above contained nearly 9 mg of melatonin, the second lot contained only 1.3 mg. That’s a variation of 465%.

Variation Could Be a Problem

Does the dose of melatonin you take matter? To some extent, yes, say the authors of a commentary on the study. Suboptimal doses might be ineffective. Taking too low a dose might lead you to believe melatonin didn’t work when a higher dose would.

Higher-than-advisable doses could lead to undesirable side effects. Too high a dose would be risky for people taking medications that interact with melatonin, or those who are pregnant or have diabetes. And the long-term effects of supplementary melatonin on prepubertal children are still unknown.

Overall Conclusions

So what are we to do with this information in light of the fact that the researchers haven’t revealed the names of the products they studied? Here’s a summary of what they learned, which, if you take or are contemplating taking melatonin, is worth consideration.

  • The least variable products overall were those containing the simplest mix of ingredients: the tablets or sublingual tablets with melatonin added to a filler. Apparently, added herbal extracts tend to make products more variable.
  • Except for the chewable tablet cited above, capsules generally showed the greatest lot-to-lot variability in melatonin content. (However, the melatonin content of some capsules was within 10% of the content listed on the label).
  • Unexpectedly, the three liquid products tested showed fairly high stability and low lot-to-lot variability.
  • The melatonin content of products listed as containing 1 or 1.5 mg of melatonin was quite a bit more likely to diverge from what was claimed than were products listed as containing higher doses. Products purportedly containing 1.5 mg of melatonin were also quite a bit more variable from lot to lot.

Unlisted Serotonin

Eight of the 30 products tested contained unlisted serotonin. While the presence of serotonin is hard to explain in supplements containing just melatonin and a filler, it might be expected in supplements containing herbal extracts. In one such product, a capsule listed as containing 3 mg of melatonin plus lavender, chamomile, and lemon balm, the serotonin content was assessed at 74 micrograms.

Serotonin raises significant health concerns if taken in excess, the Canadian authors say. It can lead to a condition called serotonin syndrome, which can be mild or fatal and “exacerbated by interactions with other medications, such as selective serotonin reuptake inhibitors and the analgesic tramadol.”

I’d like to see the content of supplementary melatonin sold in the U.S. tested and reviewed by brand and formulation. ConsumerLab? Otherwise for people using over-the-counter melatonin (or interested in trying it) it’s a kind of Wild West situation when it comes to knowing which brand to buy. Pharmacists and doctors who prescribe melatonin may be better informed. Comments?

L-Tryptophan May Help You Sleep

Interesting but dangerous: that’s what I heard about L-tryptophan supplements for several years. Research starting in the 1960s was showing that L-tryptophan might be an effective remedy for insomnia.

Then came the tryptophan-related outbreak of eosinophilia-myalgia syndrome (EMS) in 1989, killing 37 people and sickening thousands. The United States subsequently banned the supplements, and research on L-tryptophan and sleep came to a halt.

Now reviewers of alternative treatments for insomnia are again mentioning L-tryptophan as a substance of interest. Here are the pros and cons.

Mild Insomnia may respond to treatment with L-tryptophan supplementsInteresting but dangerous: that’s what I heard about L-tryptophan supplements for several years. Research starting in the 1960s was showing that L-tryptophan might be an effective remedy for insomnia.

Then came the tryptophan-related outbreak of eosinophilia-myalgia syndrome (EMS) in 1989, killing 37 people and sickening thousands. The epidemic was traced to contaminated L-tryptophan produced by a single Japanese company, but the United States banned L-tryptophan supplements from 1990 to 2001. Research on L-tryptophan and sleep came to a halt.

Now reviewers of alternative treatments for insomnia are again mentioning L-tryptophan as a substance of interest. Here are the pros and cons.

What It Is

L-tryptophan is an essential amino acid the body requires in order to synthesize proteins and other key molecules. It’s a precursor to serotonin, a neurotransmitter important to sleep, and melatonin, a hormone secreted at night.

Humans cannot produce L-tryptophan on their own. So it has to be gotten from food (or supplements). In one experiment, depriving insomniacs of L-tryptophan made their insomnia worse, as recorded by studies conducted in a sleep lab. Low levels of tryptophan resulted in sleep that was lighter and less continuous. This suggests that something about L-tryptophan facilitates sleep.

Laboratory tests show that tryptophan administered at night increases concentrations of both serotonin and melatonin in the brain. So its sedative effects are probably due to its enhancement of the melatonin or the serotonin system.

Randomized Controlled Trials

Taken at bedtime in amounts of 1 to 4 grams, L-tryptophan has been found to be at least somewhat effective for people with insomnia in several studies, including double-blind trials. But results from three randomized controlled trials, considered the highest standard of evidence, are mixed.

  1. In an early study of 96 “serious insomniacs,” weeklong treatment with tryptophan was compared with weeklong use of a placebo. No differences were noted during the tryptophan treatment—but participants taking tryptophan reported falling asleep more quickly than normal in the week following treatment.
  2. In a subsequent study, people with severe chronic insomnia were divided into two groups: one group took tryptophan nightly for 4 weeks, followed by 4 weeks of placebo; the other began with placebo and after 4 weeks swtiched to tryptophan. Group A reported improved sleep quality while taking the tryptophan; group B did not.
  3. In a more recent study, tryptophan from squash seeds and pharmaceutical-grade tryptophan, both in the form of food bars, significantly improved sleep duration and sleep quality in study participants compared with a food bar containing carbohydrate alone. The tryptophan from squash seeds outperformed the pharmaceutical-grade tryptophan in reducing time awake at night.

Well yes, these results are underwhelming.

Consider This, Too

Other research is more encouraging. L-tryptophan in some studies has reduced participants’ sleep latency and cut down on nighttime wake-ups. Reviewers make these comments:

  • The best results seem to occur in cases of mild insomnia with long sleep latency.
  • People with more severe forms of insomnia may need to take L-tryptophan for several nights before they notice improvement in their sleep.
  • In people with sleep maintenance insomnia, L-tryptophan may be more effective for those who wake up several times a night rather than for those who awaken less frequently.           

Foods High in Tryptophan

As alternative treatments for insomnia go, L-tryptophan supplements are now considered safe and relatively free of side effects. (For pregnant and breast-feeding women, however, L-tryptophan is listed as “likely unsafe.”)

But you may be able to get most of what you need in your daily diet. Meat, fish, and seafood contain lots of of L-tryptophan; eggs, cheese, and milk contain quite a bit, too. The following foods are also high in L-tryptophan:

  • soybeans and soy products
  • sesame seeds
  • seaweed
  • spinach
  • mushrooms, wild and garden variety
  • turnip and mustard greens
  • asparagus

One last caveat. By itself, L-tryptophan does not cross the blood-brain barrier. Combining an L-tryptophan-rich food with a carbohydrate greatly improves L-tryptophan uptake in the brain. So for your evening snack, have your cheese on a cracker and your tofu with rice.

If you’ve tried L-tryptophan supplements, what effect did they have on your sleep?