Eosinophilia-myalgia syndrome: a recent syndrome serving as an alert to new diseases ahead.

A recently recognized disease, the eosinophilia-myalgia syndrome, is described and presented as a new condition attributable to nutritional toxicology. Its etiology is related to the ingestion of L-tryptophan, manufactured by a single Japanese supplier who had modified its production system, which, though of high purity, contained in minute concentrations a number of contaminants or impurities. Patients with eosinophilia-myalgia syndrome develop an eosinophilia with pathologic changes mainly involving skin, muscle, and connective tissue. The findings suggest an autoimmune response. Experimental studies with the implicated L-tryptophan as well as with some contaminants have as yet failed to develop a suitable animal model of eosinophilia-myalgia syndrome. Further studies are needed to unravel the pathogenesis of this complex syndrome. At present, physicians need to be cognizant of this recent syndrome and be aware that other new diseases, induced by nutritional toxicological alterations and possibly related to technicological developments, lie ahead.