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Debunking the L-Tryptophan Myth this Thanksgiving

Tuesday, November 19, 2013

Ever blamed your family’s post-Thanksgiving meal exhaustion on the turkey? We asked Endocrinology dietitian Erika Davies to weigh in on the correlation between the l-tryptophan in turkey and drowsiness.

What is l-tryptophan?

Davies explained that tryptophan is an essential amino acid that must be obtained through diet because the body cannot produce it.  “It is a precursor to the neurotransmitter serotonin,” Davies said.

According to WebMD, tryptophan is used by the body to make niacin, a B vitamin that is important for digestion, skin and nerves, and serotonin. Serotonin is a brain chemical that plays a large role in mood and can help to create a feeling of relaxation. Tryptophan is needed to produce serotonin, which is used to make melatonin, a hormone that helps control your sleep and wake cycles.

WebMD notes that tryptophan requires assistance from foods high in carbohydrates to affect serotonin levels. As the food digests, tryptophan is competing against various amino acids in the bloodstream trying to enter the brain. It’s the carbohydrates that actually help tryptophan raise serotonin levels.

So, what causes that sleepy feeling after you gobble down a Thanksgiving meal?

While tryptophan can make a person sleepy, turkey does not contain substantially more tryptophan than other protein sources like chicken. In fact, tryptophan can also be found in cheese, milk, eggs, fish, nuts, and soy.

Davies said that the sleepiness people feel after their Thanksgiving meal is more likely due to the heavy intake of food, especially carbohydrates.

What can parents do to ensure children have a healthy Thanksgiving? 

Since most of the foods offered at Thanksgiving contain a lot of carbohydrates, Davies recommends that parents:
  • Offer non-starchy vegetable choices such as tomatoes, celery, carrots, broccoli, cauliflower, lettuce, green beans, eggplant, summer squash, onions, or peppers.
  • Try to stick to their regular meal plan, if possible.
  • Keep kids active to help them burn off all those extra carbohydrates – take a walk around the neighborhood, ride bikes, go to the park, or play outside with other family members.
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