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L-tryptophan and 5-HTP: Some Detective Work

Time and again I read about the positive impact of L-tryptophan and 5-HTP upon mood, anxiety, sleep, and more. And, of course, supplements abound. So what do you say we take an objective look.

L-tryptophan is one of eight essential amino acids for humans. What that means is we can’t synthesize it internally, so we have to obtain it through diet. L-tryptophan is the precursor of several compounds, one of which is the ever-popular neurotransmitter, serotonin.

Serotonin’s role in mood and anxiety is well known. But you may not have been aware of the fact that serotonin is the precursor of melatonin. And since melatonin is a major player in sleep, so then are serotonin and L-tryptophan.

Common dietary sources of L-tryptophan are chocolate, milk, yogurt, red meat, fish, poultry, sunflower seeds, peanuts, and eggs. And while we’re at it, let’s address a Thanksgiving/Christmas Day myth. Turkey has no more L-tryptophan than any other hunk of poultry. So if you’re looking for the cause of those post-feast sleepies, you’d be better served by taking a peak at the carbohydrate content of the other dishes.

For years, L-tryptophan has been available as a dietary supplement. In addition to being used as a mood enhancer and sleep aid, it’s shown promise in the treatment of specific situations such as premenstrual dysphoric disorder (PMDD) and seasonal affective disorder (SAD). It’s also shown promise as an independent antidepressant, as well as a supplement to an existing antidepressant regimen.

Of note, there was a large L-tryptophan-related outbreak of something known as eosinophilia-myalgia syndrome (EMS) in 1989. The final score was 1,500 cases of permanent disability and at least 38 deaths. How did that happen? Well, several theories have been offered. The one that seems to stick is the outbreak being traced to L-tryptophan supplied by a Japanese supplement manufacturer. It seems genetic engineering used in production may have been the culprit.

The sale of most L-tryptophan was banned in the United States in 1991. And even after it was known that a contaminated batch caused the outbreak, and the manufacturing process had been fixed, the FDA still maintained L-tryptophan was unsafe. Finally, in 2001, the FDA loosened up, but still issued a cautionary statement.

Since 2002, L-tryptophan has been sold in the United States in its original form.

5-Hydroxytryptophan (5-HTP) is a naturally-occurring amino acid, and is a catalyst in the synthesis of serotonin and melatonin from L-tryptophan. Bottom-line: it increases the production of serotonin.

5-HTP is primarly used as a mood enhancer and sleep aid. It’s also been reported to be an effective appetite suppressant. In addition, it’s shown promise in the treatment of fibromyalgia, anxiety, and binge-eating associated with obesity.

Like L-tryptophan, 5-HTP is sold over-the-counter in the United States as a supplement. And what makes this especially important is the fact that dietary sources of 5-HTP are insignificant.


L-tryptophan and 5-HTP, in supplement form, appear to be worth considering as one seeks relief from mood, anxiety, and sleep issues. But I have to emphasize that some studies have shown mixed results in terms of efficacy, and researchers have gone so far as to question the reliability of any conclusions drawn by a significant number of studies.

Finally, don’t ever, ever, ever forget – L-tryptophan and 5-HTP can lead to some very dangerous physical issues. And you just never know. So, please, do your research and consult your physician before beginning a regimen.

Oh, here’s a resource that may be helpful. It’s the website of the National Institutes of Health’s National Center for Complementary and Alternative Medicine. Check it out here.

That will be that. I hope the information will be helpful, and I encourage you to add your input by commenting. Thanks!