FDA Refuses to Lift Ban on Sale of Food Supplement L-Tryptophan

The U.S. Food and Drug Administration said Tuesday that it will not allow L-tryptophan back on the market, despite a call by the Costa Mesa-based National Nutritional Foods Assn. to lift the agency’s ban on the food supplement.

The FDA’s statement in Washington came despite news that a study will be published today in the Journal of the American Medical Assn. indicating that an epidemic of a potentially fatal blood disorder may be linked to only one manufacturer of the food supplement.

An Oregon study by the Centers for Disease Control indicated that a worldwide epidemic last year of eosinophilia-myalgia syndrome “was caused by a contaminant or an alteration in a subset of L-tryptophan manufactured by a single company in Japan shortly before the outbreak began,” said the study’s lead investigator, Dr. Laurence Slutsker.

Slutsker said that the Minnesota Health Department has completed a similar study, as yet unpublished, that also links the disease to one manufacturer, Showa Kenko of Japan. He added that preliminary results of studies by state health departments of New Mexico and New York have yielded the same finding.

The Costa Mesa group, which represents health food retailers and manufacturers, and other health food industry officials argue that these studies give sufficient evidence that L-tryptophan produced by five other Japanese firms is safe and should be allowed back on the market as a treatment for ailments such as insomnia and premenstrual syndrome.

However, the FDA in its statement Tuesday said that additional studies of a wider geographic area are needed to determine whether the contaminants being found in L-tryptophan cause EMS or simply are indicators of another agent that causes the disease.

Slutsker said that putting L-tryptophan back on the market now without further studies would be “premature.”