Eosinophilia-Myalgia Syndrome: The 1989 Tryptophan Outbreak
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Eosinophilia-myalgia syndrome

Also called EMS, tryptophan outbreak, L-tryptophan EMS · Reviewed

Definition: Eosinophilia-myalgia syndrome (EMS) is an illness that was linked to tryptophan supplements in a 1989 outbreak. The name means a high level of eosinophils, a type of white blood cell, together with muscle pain. A 1990 study tied the outbreak to tryptophan made by one company under specific manufacturing conditions.

What the 1990 study found

Belongia and colleagues, led from the Centers for Disease Control, studied cases in Minnesota. Among people whose tryptophan source was known:

  • 29 of 30 patients (97%) and 21 of 35 controls (60%) had taken tryptophan from a single maker;
  • the patients' lots were linked to less powdered carbon in a purification step and a new bacterial strain used in fermentation;
  • one lab peak, called peak E, was in 9 of 12 lots used by patients and 3 of 11 used by controls.

The authors concluded the outbreak came from a chemical in the product tied to those manufacturing conditions, not clearly from tryptophan itself.

Why it is a quality story

The same ingredient made two ways gave different results. That is why lab tests such as an HPLC purity check and a certificate of analysis matter for any dietary supplement or research product, since small impurities can matter.

Why it matters for your log

The study traced cases to specific retail lots. Writing down the brand and lot number of what you take, next to your start date, is what makes that kind of tracing possible.

Read more on Dose Track: Side-by-side comparisons · Side effects from FDA labels

General education drawn from labels and published studies, not personal medical advice. Your prescriber, pharmacist and the label that came with your product are the final word.
Dietary supplementA dietary supplement , under US law (21 U.S.C. 321(ff)), is a product intended for ingestion to supplement… HPLC purityHPLC purity is the percent of a sample that is the intended compound, measured by high-performance liquid… Certificate of analysis (COA)A certificate of analysis (COA) is a document listing test results for one batch (lot) of a product: what… New dietary ingredientA new dietary ingredient (NDI) is a dietary ingredient that was not marketed in the United States before…

Frequently asked questions

What caused the 1989 eosinophilia-myalgia syndrome outbreak?+
A 1990 study linked it to tryptophan from one maker and to specific manufacturing conditions, and concluded a chemical constituent of the product was responsible, possibly the one seen as peak E.
What does eosinophilia-myalgia mean?+
A high level of eosinophils, a type of white blood cell, together with muscle pain (myalgia).

Sources

  1. Belongia EA et al. An investigation of the cause of the eosinophilia-myalgia syndrome associated with tryptophan use. N Engl J Med 1990;323:357-65 (PubMed 2370887)

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