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Getting sleepy after a big holiday meal? Don’t blame the turkey


If you feel sleepy after your holiday turkey dinner, don’t blame the bird, says Texas A&M University Professor Nicolaas Deutz.

As the myth goes, an amino acid found in turkey called tryptophan causes drowsiness.

But according to Deutz, an expert in nutrition and a professor at Texas A&M’s Center for Translational Research in Aging and Longevity (CTRAL), that theory is wrong on several levels.

As he points out, drowsiness after a turkey dinner is much more likely due to the quantity of food rather than the turkey itself. Also, turkey contains no more tryptophan than any other kind of poultry. In fact, he says, tryptophan can be found in almost any protein.

“This story about tryptophan in turkey is just kind of a running joke,” he insists. “It has nothing to do with the tryptophan.”

On a more practical level, he hopes that he can use the amino acid to help patients with a disease that is no laughing matter: multiple sclerosis.

In a study funded by the Maastricht University Medical Center, he explores the potential for tryptophan-enriched diets to improve the mood and cognition of patients with the debilitating disease.

Even though multiple sclerosis typically affects younger people between the ages of 20 and 50, CTRAL – a center that is focused on improving the lives of much older adults – has a special interest in studying treatments for multiple sclerosis.

“In many ways, multiple sclerosis is almost like the brain getting older on its own,” Deutz explains. “The memory problems really look similar to dementia, Parkinson’s and other diseases that affect older people.”

In the past he conducted research in which his team reduced tryptophan in their diets and saw several negative effects on memory and cognition. In patients with depression, it worsened their moods.

As he saw it, the next logical question to ask was: If a decrease in tryptophan levels worsens those symptoms, can an increase have the opposite effect?

Deutz also conducts research on people with minimal cognition deficiency, or what he calls a very mild form of dementia. That is people who, for example, have trouble finding their keys in the morning.

In addition to cognitive improvement, he and his team monitor changes in metabolism levels as a possible cause for memory loss.

Researchers had been attempting for decades to conduct similar experiments, until the discovery of a toxic byproduct in tryptophan supplements halted those efforts. Now, patients can ingest the amino acid via natural proteins.

“This research has been around for nearly 30 or 40 years,” Deutz explains. “What makes it new is finally bringing it to a translational/clinical level and having a practical application. We now have more tools to measure metabolism and safer ways to digest large amounts of tryptophan.”

To participate in this active study, visit CTRAL’s website at: