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Law Topics >Injuries > l-tryptophan

FDA scientists have confirmed the presence of impurities in some 5-hydroxy-L-tryptophan (5HTP) products currently marketed and widely promoted as dietary supplements. These products are being used as aids for insomnia, depression, obesity, and in children with attention deficit disorder. The FDA's analytical results are consistent with those obtained and published by researchers from the Mayo Clinic.

One of these impurities is known as "peak X." Although the significance of finding "peak X" and other impurities in dietary supplements containing 5-HTP is unknown, past experiences with these products suggests vigilance is warranted. "Peak X" was identified in one case of the illness eosinophilia-myalgia syndrome (EMS) associated with 5HTP in 1991. Impurities similar to "peak X" were also found in L-tryptophan that was associated with a 1989 epidemic of EMS. 5HTP and L-tryptophan are related in that 5HTP is synthesized from L-Tryphophan in the body. The exact cause of the 1989 epidemic and of the case of EMS associated with 5HTP remain unclear.

EMS is a serious systemic illness characterized by elevations of certain white blood cells and severe muscle pain. The Centers for Disease Control and Prevention (CDC) has identified more than 1,500 cases of EMS, including at least 38 deaths associated with the use of L-tryptophan. The medical literature reports approximately 10 previous cases of EMS worldwide associated with use of products containing 5HTP.

Research has not resolved whether these EMS cases were caused by L-tryptophan or 5HTP, one or more impurities, or other factors. At this time, the FDA is unaware of any recent illnesses associated with the 5HTP products being sold as dietary supplements. The widespread promotion and use of these products, however, began only recently.