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Potentially Harmful Contaminant Discovered in Popular Dietary Supplement, 5-HTP
ROCHESTER, MINN. -- Mayo Clinic researchers report finding low levels of a potentially harmful contaminant in off-the-shelf samples of a popular dietary supplement, 5-Hydroxy-L-Tryptophan (5-OH-
Trp or 5-HTP).
The contaminant, called "peak x," was linked to symptoms suffered by a family exposed to 5-HTP in 1991. It also has a similar chemical structure to contaminants found in batches of a related supplement, L-Tryptophan, which were linked to a 1989 outbreak of eosinophilia myalgia syndrome (EMS) that affected thousands of people.
The researchers say the finding is a "red flag" about the possibility of health risks from taking this supplement in large doses. Their report will be published in the September 1 issue of Nature Medicine.
Using sophisticated chemical analysis techniques, Mayo Clinic researchers analyzed pills from six samples of 5-HTP produced by six different manufacturers. Samples were purchased at health and nutrition stores in New York City and Rochester, Minn.
They found peak x in all six samples, both synthetic and natural extract preparations. The levels of peak x were only a fraction (between 3 and 15 percent) of the level that caused the illness in the earlier incident. The researchers warn, however, that, "as the intake of supplements is not medically supervised, the probability of increased doses of 5-OH-Trp and hence, peak x, being consumed is very real."
They point out that a current book (5-HTP: The Natural Way to Overcome Depression, Obesity and Insomnia) recommends consumption of 300 to 900 milligrams per day of the supplement. They say that if followed, this recommendation could bring the consumption level of peak x to levels associated with problems in the past.
The authors say that the potential health risks of dietary supplements were clearly demonstrated in the 1989 outbreak of EMS which killed at least 30 people and sickened more than
1,500. That outbreak was linked to consumption of a contaminated batch of the supplement L-tryptophan. Six different contaminants were linked to illnesses. Mayo Clinic physicians and researchers diagnosed and treated many victims of that outbreak and played a key role in identifying the contaminants that were likely responsible for the illness.
Mayo Clinic researchers have characterized the chemical structure of peak x for the first time. They have discovered that peak x is, in fact, a family of nearly identical compounds. Their chemical structure is similar to two contaminants found in the L-tryptophan linked to EMS symptoms in 1989.
The Mayo researchers have previously raised similar questions about the purity of another popular dietary supplement, melatonin. In several recent publications, they report identification of contaminants in commercial preparations of melatonin whose chemical structure is very similar to some of the contaminants implicated in the L-tryptophan outbreak, as well as to peak x from 5-HTP.
The Mayo research team, led by Stephen Naylor, Ph.D. and Gerald Gleich, M.D., say that their study "emphasizes the need for tighter quality control for the production of both synthetic and 'naturally' produced nutritional supplements" to prevent the possibility of another epidemic in the future.
Mayo researchers have informed the Food and Drug Administration of their findings. They also have provided a description of testing methods used to the six manufacturers of 5-HTP included in the study so that they could confirm the study's findings.
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