Investigations determined an impurity in the manufacturing process was the
An impurity in a manufacturing process unrelated to biotechnology was the
cause of the harmful effects.
L-Tryptophan is an amino acid that occurs naturally in protein-containing
food (e.g. milk, turkey). Amino acids are building blocks of protein.
Until 1990, L-Tryptophan was manufactured and sold in the United States in
pill form as a dietary supplement. The Food and Drug Administration (FDA)
ordered L-Tryptophan pulled from store shelves after 36 deaths and illnesses
in 1989 and 1990 were linked to consumption of the supplement in the United
In 1989, an outbreak of an extremely rare blood disorder,
Eosinophilia-Myalgia Syndrome (EMS), developed in the United States.
Thirty-six people died from EMS-related complications, and another 1500
became seriously ill (NYT, 8/31/98). 95% of these cases involved users of
L-Tryptophan supplements manufactured, imported, and distributed by Showa
Denko, a Japanese company (Food Chemical News, 10/19/92) (PR Newswire,
National Nutritional Foods Association, 7/9/90).
In 1990, the FDA recalled all capsules or pills providing 100 mg or more of
L-Tryptophan in a daily does and banned all sales of the supplement pending
further investigation (FDA letter, 1/17/90). The ban remains in effect
Some have raised the question of the role that a genetically engineered
bacterium (known as Strain V) may have played in Showa Denko's manufacturing
process of some lost of L-Tryptophan (Newsday, 8/14/90).
· After years of investigation, no evidence exists that links EMS and
genetic engineering. Dr. Gerald Gleich of the Mayo Clinic, who testified
for the injured plaintiffs in litigation against Showa Denko, published a
paper exonerating genetic engineering (BIO insert re: L-T, 1/26/98; see
Mayeno and Gleich 1994, Trends in Biotechnology, also known as TIB TECH,
vol. 12, pp. 346-352).
· Rather, most experts agree that the available evidence suggests that an
impurity in Showa Denko's manufacturing process of certain batches of
L-Tryptophan existed and was the cause of the toxic effects (NYT, 8/31/98;
BIO Insert re: L-T, 1/26/98).