There's reportedly good Thanksgiving news for turkey lovers: Contrary to popular belief, tryptophan in turkey doesn't cause drowsiness.

In fact, scientists told National Geographic News the substance could possibly aid in the treatment of depression and multiple sclerosis.

Purified tryptophan is a mild sleep-inducing agent and that probably led to the idea that foods containing heavy doses of the chemical cause drowsiness.

But tryptophan can't function well as part of a meal.

"Tryptophan is taken to the brain by an active transport system shared by a number of other amino acids and there's competition among them -- like a crowd of people trying to get through a revolving door," Simon Young, a neurochemist at McGill University in Montreal, Canada, told National Geographic News.

He said consuming tryptophan-rich foods may cause blood levels of the amino acid to rise, but not enough tryptophan will reach one's brain to have a sedative affect.

And, scientists told NGN, turkey isn't even unusually high in tryptophan. Many other foods, such as beef or soybeans, have higher concentrations.

Copyright 2005 by United Press International

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