Learning Lab Denmark - INCUBEus


The molecular engineered amino acid L-Tryptophan with the empirical formula C11H12N2O2 was marketed in the US in 1989 as a food supplement by the company Showa Denko K.K. It was freely available on shelves of health stores.

Within a few months, 37 people had died from taking the drug and another 1,500 had permanent disabilities. They had developed EMS, which is a systemic connective tissue disease characterised by severe muscle pain, an increase of white blood cells and certain skin and neuromuscular manifestations. At least 850 lawsuits for roughly $1 billion dollars were filed.

A definitive answer on the cause of the toxic effects was never reached because all relevant evidence in Showa Denko’s laboratory was destroyed before it could be examined.

Two explanations are considered plausible: either the company failed to purify the batches in question, or the molecular engineered mechanism developed a new and extremely toxic impurity. The accident has been subject to intense public debate due to its relation to genetic engineering.

To date, despite the L-tryptophan tragedy, the biotech companies and the US government continues to state that the drug has not caused any human health problems in the US and that company risk assessment methods are adequate.

In September 1999, David Aaron, U.S. deputy secretary of commerce, declared, “Not a rash, not a sneeze, not a cough, not a watery eye has been developed from this.”

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Links and references:

American Food & Drug Administration:

Paper about genetic engineering:

Information Paper on L-tryptophan and 5-hydroxy-L-tryptophan from the U. S. Food and Drug Administration:

Card: L-Tryptophane
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