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Turkey and Tryptophan—does it make us drowsy?
Turkey and Tryptophan—does it make us drowsy?Joyce E.M. Wall

Is turkey responsible for the sleepiness that occurs after enjoying a Thanksgiving dinner? Turkey contains tryptophan, an amino acid that is important in our diet. Tryptophan is a precursor for the production of serotonin, a neurotransmitter that influences a calming, sleep-inducing effect on the brain.

Until 1989, tryptophan supplements were dispensed over-the-counter and were used for appetite control, depression, stress reduction, and as a sleep aid. The supplements were recalled by the U.S. FDA after a contaminated lot manufactured in Japan was associated with an outbreak of a potentially fatal condition known as eosinophilic myalgia syndrome (EMS). This painful blood disorder causes high fever, rash, weakness, and shortness of breath. During that outbreak, over 1,500 people were reported to have contracted EMS with at least 37 fatalities.

So, does turkey really make you drowsy? No—it’s a myth! In order for the tryptophan in turkey to produce a sedative effect, it has to be taken on an empty stomach. However, after a typical thanksgiving meal of turkey, stuffing, sweet potatoes, gravy, cranberry sauce, and pumpkin pie, the tryptophan doesn’t stand a chance in your digestive system. It is unlikely that the tryptophan will cause any sedative effects when ingested with other foods.

So, why is there a difference in body responses when we take tryptophan supplements compared with consuming it through the diet? When people take tryptophan supplements, the purified compound can get to the brain with relative ease. But after a turkey feast, the tryptophan molecules are slowed down. They are circulated through the body as part of a package with lots of other competing amino acids. There is competition for those amino acids to cross the blood-brain barrier and their potential to pass through quickly is greatly reduced.

Then why are we drowsy after a Thanksgiving feast? We typically feel sleepy after consuming large quantities of food, especially if the meal is high in carbohydrates with potatoes, bread, and sweet desserts. Alcohol consumption can also have a sedative effect and contribute to lethargy. Or, maybe we are just so relaxed around our family and friends that we just want to sleep!

Reference links:

  1. http://www.npr.org/templates/story/story.php?storyId=97449569

Copyright ©2010 Joyce E.M. Wall

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