By Lisa Justice
If you’ve ever enjoyed a traditional American Thanksgiving feast with turkey and all the trimmings, you’re probably familiar with the post-meal lethargy that’s almost as much a part of the holiday celebration as football. The turkey itself is often blamed as the culprit behind our sleepiness, but is that blame well placed?
The turkey usually attracts the pointing fingers because of its levels of the amino acid L-Tryptophan. L-Tryptophan, like all amino acids, is a building block for the essential proteins our bodies need and can be found in a variety of protein-rich foods, including eggs, chicken, cheese, red meat, yogurt and fish.
So why does L-Tryptophan attract so much attention in the Thanksgiving turkey? L-Tryptophan has been documented as contributing to drowsiness. L-Tryptophan helps your body produce niacin, a B-vitamin that, among other things, is helpful for seratonin.
Seratonin is a chemical in your brain that allows you to relax and contributes to restful sleep. L-Tryptophan also boosts your body’s ability to generate melatonin, a hormone that signals your brain when it’s time to sleep.
So L-Tryptophan certainly is related to sleepiness, but if it’s present in so many other foods, why don’t we experience Thanksgiving levels of drowsiness every time we have a yogurt? The answer lies beyond the turkey and with everything else that comes with your holiday spread.
If the L-Tryptophan from the turkey were a lone amino acid all by itself, it could go straight to your brain and start boosting levels of seratonin and melatonin. But it’s not. There are many other amino acids in the turkey and other dishes that compete with L-Tryptophan for your brain’s attention and block L-Tryptophan from getting to your brain.
That’s where the carbohydrates from dishes like stuffing and potatoes kick in. These carbohydrates trigger your pancreas to release insulin into your blood stream. This process drives some of the other amino acids, the ones blocking the L-Tryptophan from getting to your brain, out of your blood stream and into other tissues. The carbohydrates therefore help reduce L-Tryptophan’s competition and allow more of it to get to your brain.
Eaten by itself, turkey or any other animal protein would not necessarily make you drowsy right away as the combination of amino acids would prevent a rush of L-Tryptophan. However, when L-Tryptophan teams up with carbohydrates, your chances of drowsiness increase.
And then think about how much food you consumed. A large meal requires a lot of energy to digest, so your body will direct all its resources to your digestive system, leaving your brain to want to settle down for a long winter’s nap. And if alcohol was part of your feast, its depressive qualities also can contribute to a desire for decreased activity.
So while turkey does contain a chemical that can assist in inducing nap time, the bird itself cannot be held fully responsible for general Thanksgiving sleepiness. In fact, turkey contains less L-Tryptophan than chicken or milk! So as you’re diving into your celebration this year don’t be hasty to blame the turkey for any grogginess, but rather marvel at how all your foods work together to both fuel your body and inspire it to rest.
* Thanksgiving break: Explorit’s “Beyond the Table” exhibition will be open from 1 to 5 p.m. Saturday through Wednesday and Friday through Sunday, Nov. 23-25. We hope you will join us for some science fun and discovery over the holiday break.