"Are Melatonin Supplements Safe?"
If you’re crossing three or more time zones,
and you plan on staying at your destination
long enough to make it worthwhile,
you can adjust your body clock
to the new time
with behavioral methods
or pharmacological methods.
The behavioral method is light exposure
and light avoidance at specific
times of the day based on
which direction you’re going
and how many time zones you cross.
You may want to take a snapshot
of this table for future reference.
The pharmacological intervention is melatonin,
the so-called ‘‘darkness hormone.”
It’s secreted by a little gland
in the center of your head
as soon as it gets dark
and shuts off when the sun
comes up in the morning,
thereby helping to set
your circadian rhythm.
There’s been a lot of research done
on treating jet lag,
but most of it has come from lab rats
instead of people.
But, most of the handful of human trials
that have been done have found
taking melatonin close to the target
bedtime at the destination to try
to sync your body to the new time
can effectively decrease jet lag
symptoms after long flights.
Now, unlike most or really all other drugs,
the timing of the dose is critical
and determines the effect;
given at the wrong time,
it can make jet lag even worse.
For example, if you were to take melatonin
at bedtime when traveling west.
Dose-wise, taking between 0.5 and 5mg
seems to be similarly effective
in terms of helping with jet lag symptoms,
but the higher dose does seem to have
more of a sleeping pill-type effect,
which appears to plateau at about 5mg,
but those are massive doses.
Even just taking a 3 mg dose produces
levels in the bloodstream 50 times
higher than normal nightly levels.
Yeah, it works, but we don’t know
how safe that is.
After all, melatonin in the early days
used to be known as an anti-gonad hormone,
with human equivalent doses of just
a milligram or two reducing the size
of sex organs and impairing fertility
in laboratory animals.
Now, obviously, rats aren’t people,
but considering the pronounced effects
of melatonin on reproductive physiology
in other mammals, to assume that it would
not have some sexual effects in humans
would almost seem naive.
In fact, they speculate, maybe melatonin
could one day play a role as some
sort of a contraceptive agent.
Wouldn’t we know about these effects though?
How?
Melatonin is available over-the-counter
as a dietary supplement, so there's no
post-marketing surveillance
like there is with prescription drugs.
And then, there’s the purity problem.
Supplements are so poorly regulated
that you never really know
what’s actually in them.
For these reasons, melatonin supplements
cannot be recommended.
Is the purity issue just theoretical though?
You don’t know, until you...
put it to the test.
And, indeed, due to the poor quality control
of over-the-counter melatonin,
what they say is often not what you get.
Melatonin is not only one of the most
popular supplements among adults,
but children too, which makes it even
more egregious that actual melatonin
content varied up to nearly 500%
compared to what it said on the label,
based on an analysis of 31 different brands,
and most had just a fraction of what they said.
And, the most variable sample was a chewable tablet,
which is what kids might take.
It said it had 1.5mg but actually had 9,
which could result in like a hundred times
higher than natural levels.
In short, there was no guarantee
of the strength or purity
of over-the-counter melatonin,
leading these researchers to suggest it
should be regulated as a drug so that,
by law, at least it would have what
it says on the bottle.
OK, but that’s strength.
What about purity?
Four of six melatonin products from health food stores
—2/3 contained unidentified impurities.
With no exclusive patent,
no pharmaceutical company wants to pay
for the necessary toxicological studies—
the stuff is just sold so dirt cheap.
They recommend buying it from
some large, reputable pharmacy chain
and just hoping for the best,
but this study suggests
it’s not worth the risk.
Contaminants present in tryptophan supplements
were reported to be responsible for a
1980’s outbreak of a disease that affected more than
a thousand people and resulted
in dozens of deaths.
Given the structural similarities of tryptophan and melatonin,
maybe when you’re trying to synthesize melatonin,
those same toxic contaminants could be created—
and, indeed, here’s the contaminant blamed
on the tryptophan epidemic,
and here’s what they found in melatonin supplements.
That’s a little too close for comfort,
suggesting melatonin supplements
may just be another accident—
another epidemic, waiting to happen.