Tryptophan was a popular over the counter supplement here in the US twenty years ago, used as a sleep aid (and for other
indications). However, there was a problem with the processing of a certain brand (or brands by one manufacturer) of tryptophan
supplement that led to a serious, sometimes fatal condition called eosinophilia-myalgia syndrome (EMS) years ago and caused
tryptophan to be pulled off US shelves.

L-tryptophan is an amino acid. FDA took action to limit the availability of L-tryptophan supplements because of the association
between dietary supplements containing L-tryptophan and the 1989 epidemic outbreak of eosinophilia-myalgia syndrome (EMS) in the
United States.

In the summer and fall of 1989, an epidemic outbreak of eosinophilia-myalgia syndrome (EMS) occurred in the United States. This
illness is associated with the use of dietary supplements containing L-tryptophan. In all, more than 1500 cases of EMS, including at
least 37 deaths, have been reported to the national Centers for Disease Control and Prevention (CDC), although the true incidence of
the disorder is thought to be much higher. Some individuals suffering from L-tryptophan-related EMS have recovered, while other
individuals' illnesses have persisted or worsened over time.

Two case-control studies initiated by the health departments in New Mexico and Minnesota confirmed a strong association between the
use of a specific brand of L-tryptophan and development of EMS. With the recall of L-tryptophan from the market in November 1989, a
precipitous fall was observed in the incidence of EMS.

Note that it was believed to be a problem in the processing, and not the tryptophan itself, which caused the damage.  

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. 

Pathophysiology: The pathogenesis of the disease remains unknown. The 3 major pathological findings observed in persons with EMS are
(1) endothelial cell hyperplasia in the capillaries, with evidence of swelling and necrosis; (2) an inflammatory cell infiltrate of
predominantly monocytes, histiocytes, lymphocytes, macrophages, and plasma cells and occasionally eosinophils in nerve, muscle, and
connective tissue, including the subdermal fascial layer (fasciitis); and (3) increased fibrosis, mostly in the fascia.

Frequency:

    * In the US: By July of 1991, 1543 cases were reported to the CDC. However, estimates indicate that 5,000-10,000 people actually
have EMS. 

    * Internationally: Reports indicate that EMS occurs in other parts of the world, including the United Kingdom, France, Israel,
Japan (12 patients), western Germany (69 patients), and Canada (10 patients). Cohort studies performed during the epidemic estimated
the attack rates for EMS among users of L-tryptophan to be 0.5-9%, depending on the product lot of the L-tryptophan ingested. Since
the epidemic of 1989-1991, only a few new cases have been reported. 

Mortality/Morbidity:

    * By July 1991, 31 deaths were attributed to EMS. The mortality rate ranged from 2% in national surveillance data to 6% in some
cohorts. Most deaths were the result of neurogenic causes, including ascending polyneuropathy, cardiopulmonary disease, and
superimposed infection. 

    * Of the patients with acute illness, 34% required hospitalization for incapacitating myalgia, muscle cramps, or pulmonary
involvement.

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