Short for 5-hydroxy-L-tryptophan, 5-HTP is a natural stepping-stone between a nutrient in our food and a crucial compound in our brains. Specifically, it's a substance that links the amino acid tryptophan to the chemical messenger serotonin. Tryptophan, which our bodies can't make but we do get from many foods, quickly turns to 5-HTP in the brain. 5-HTP, in turn, rapidly becomes serotonin, a compound that plays a large role in controlling mood, appetite, and sleep cycles. (You've probably heard of serotonin in the context of antidepressant drugs that seem to work by keeping up its presence in the brain.) Among other things, 5-HTP has been used to treat insomnia, migraines, fibromyalgia, attention deficit disorder, and Parkinson's disease.

Because extra tryptophan in our diets leads to extra serotonin in our brains, tryptophan supplements became extremely popular in the 1980s as a natural remedy for insomnia, obesity, and depression. The enthusiasm ended when more than 1,500 people developed a crippling disease, eosinophilia-myalgia syndrome (EMS), after taking tryptophan supplements tainted with an impurity similar to one found in 5-HTP that's known as "Peak X." Thirty-eight of the victims died. (Many cases were linked to a batch of genetically engineered tryptophan supplements from Japan.)

The Food and Drug Administration banned tryptophan supplements in 1990, a move that led to a wave of supplements containing 5-HTP. Today 5-HTP supplements are sold everywhere in countless health food stores and on the Web and promoted with the same promises that were once made about tryptophan.

5-HTP is used to treat a rare condition called post-anoxic myoclonus, which causes involuntary muscle contractions.

The FDA hasn't learned of a recent illness linked to 5-HTP, although peak X was linked to a 1991 case of EMS in a consumer taking 5-HTP. Nonetheless, the agency warns of the need for caution. In 1998, researchers at the Mayo Clinic tested six batches of 5-HTP and discovered small amounts of peak X - similar to the contaminant that caused the outbreak of EMS -- in every one of them. (Later tests by the FDA also found the contaminant.)

The analyzed 5-HTP supplements contained only 3 to 15 percent as much peak X as did the tainted tryptophan, but that's enough to put people taking large amounts of 5-HTP at risk. One book, 5-HTP: The Natural Way to Overcome Depression, Obesity, and Insomnia, recommended taking 300 to 900 milligrams of the supplement each day, and Mayo Clinic researchers say such doses could easily cause trouble. If you take 5-HTP, keep the dose small and see your doctor if you notice any signs of EMS, which include fatigue, muscle pain, numbness, and tingling.

Even if you happen to get a pure batch of 5-HTP, the supplement's effects may not always be benign. Users can become manic, restless, irritable, and (though it's less common) depressed, according to a study in the Archives of Neurology. That's all the more reason to use 5-HTP with caution -- or to steer clear of it. Women who are pregnant or nursing should avoid the supplement entirely.

For depression, the typical dose is 150 to 300 miligrams daily.

Yes. Watch out for the following interactions:

•Taking 5-HTP along with carbidopa (used with L-dopa to treat Parkinson's disease) may cause hardening of the skin similar to scleroderma.

•If you combine 5-HTP with many antidepressants drugs (including tricyclics, monoamine oxidase inhibitors, selective serotonin reuptake inhibitors such as Prozac, and other serotonin agonists), you run an increased risk of harmful side effects.

•Taking 5-HTP with serotonin antagonists reduces the effectiveness of these drugs.

As a forerunner to serotonin, 5-HTP may have the potential to stabilize mood. One small 6-week study compared 5-HTP to an antidepressant in the Prozac family and found equal benefit between the two, with 5-HTP causing fewer and less severe side effects. In another interesting study, researchers found that children treated with 5-HTP for night terrors showed significant long-term improvement.The substance also shows some promise as an antiobesity aid: An Italian study of 25 overweight people with Type 2 diabetes found that subjects who took 750 mg of 5-HTP each day for two weeks ate less fat and carbohydrates and lost weight. As for insomnia, studies from the 1960s and 1970s suggest that tryptophan supplements helped people fall asleep, and 5-HTP may have a similar effect. And although it's not widely advertised, 5-HTP may ease the pain of fibromyalgia. In an Italian study of 50 patients, reported in the Journal of International Medical Research, half of the subjects reported less discomfort after taking 5-HTP for 90 days. But with all the unanswered questions about the product, you're better off using more widely tested remedies.

-- Chris Woolston, M.S., is a health and medical writer with a master's degree in biology. He is a contributing editor at Consumer Health Interactive, and was the staff writer at Hippocrates, a magazine for physicians. He has also covered science issues for Time Inc. Health, WebMD, and the Chronicle of Higher Education. His reporting on occupational health earned him an award from the northern California Society of Professional Journalists.

References

First published January 26, 2000
Last updated January 31, 2008
Copyright © 2000 Consumer Health Interactive

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