Pupillary Pathways

Food Coma? The Truth about Tryptophan on Thanksgiving

Posted by Amanda Dexter on Nov 26, 2015 8:00:00 AM
Amanda Dexter
Dr. Amanda K. Dexter received her optometric training at Southern California College of Optometry in Fullerton, California, where she was Class of 2010 Valedictorian. She also completed a residency in Primary Care and Ocular Disease at the Veteran's Affairs Hospital in San Diego, California. Dr. Dexter is the Manager and Program Coordinator for OptoPrep, the premiere online study resource for the NBEO Part I & II.

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You’ve just finished a nice big plate of juicy turkey, flavorful stuffing, creamy mashed potatoes and gravy, sweet homemade cranberry sauce, and deliciously spiced pumpkin pie, all washed down with a hearty glass of Pinot Noir.

As you are helping your mother clean up the kitchen, while continuing to engage in conversation with your aunts and uncles you haven’t seen in a while, you start to feel a bit sleepy. Your cousin makes a joke about how everyone is about to fall into a food coma because of all the tryptophan that was eaten, but you let him know that this is a myth. Other family members side with him because that’s something that they have heard for years. 

So who is correct? Is the tryptophan on thanksgiving in the turkey really to blame for tiredness after dinner? Is there truth to the tryptophan theory, or is it really a myth?

The answer is… Don’t blame it on the bird

turkey-png-8.pngContrary to popular belief, eating turkey isn’t the main reason you feel sleepy after your Thanksgiving feast. The often-repeated turkey myth stems from the fact that turkey contains the amino acid tryptophan. Tryptophan is a component of the brain chemical serotonin, which eventually gets converted to the well-known sleep-inducing hormone melatonin. 

Although turkey does contain a significant amount of tryptophan, studies have shown that turkey isn’t any more sleep-inducing that other foods. In fact, many other foods actually have much more tryptophan than turkey. These include spinach, soy, fish, and cheddar cheese. 

So what’s the real culprit?

Post-meal drowsiness on Thanksgiving has more to do with what else is on your plate, than the actual turkey itself. It’s more likely that consuming large amounts of carbohydrates, fats, and alcohol may be the real cause of the post-Thanksgiving meal snooze. 

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We all know that when you eat a ton of carbs (mashed potatoes, stuffing, rolls, etc), your body releases extra insulin to keep your blood sugar levels in check. This in turn triggers the uptake of most types of amino acids from the bloodstream into the muscle cells. Tryptophan is an amino acid that is not removed from the blood as much as some of the others. Therefore, the relative concentration of tryptophan in the blood increases. Now it can better make its way to the brain to produce serotonin and that familiar sleepy feeling that follows. 

Other experts blame the fat in our side dishes for the sleepiness. Fat takes a lot of energy to digest, so the body redirects blood flow to the digestive system. More blood to the gastrointestinal system means less going elsewhere, and reduced blood flow throughout the body will ultimately lead to a feeling of tiredness. 

Let’s also not forget the alcohol either. A couple of beers, or a couple glasses of wine with your Thanksgiving dinner can add to the nap-factor. Alcohol is a central nervous system depressant, and when added to a large meal, just plain tiredness from all the conversations with friends and relatives, and the work of simply preparing the Thanksgiving meal itself, fatigue can set in pretty easily post-meal time. 

So… don't blame the bird, blame all the side dishes you ate with it. And don’t feel bad about taking a little nap! You’ve worked hard studying for exams and boards, so embrace the relaxation, the delicious hearty meal, and the inevitable food coma! 

Fun Turkey Facts to Replace the Tryptophan Tale:

Since we’ve determined the truth about tryptophan, here are a few cool facts to tell your friends and family during dinner to replace this old myth… 

  • Turkeys may be descendants of the T. Rex and Velociraptor!
  • Despite their size and weight, turkeys sleep in trees!
  • Female turkeys don’t gobble, only males do!
  • Wild turkeys can fly up to 55 miles per hour!
  • Turkeys have periscopic vision and can see 360 degrees peripherally! 
  • Turkeys have 2 stomachs, one of which contains tiny stones for digestion!

Happy Thanksgiving!

-Dr. Dexter

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Topics: Holidays