As we celebrate one of America’s favorite holidays, a day our ancestors set aside to give thanks for a plentiful harvest. It’s a time to reconnect with friends and family we haven’t seen in a while, with lots of food, fun and football. Many of us will settle in for a big meal with turkey, dressing and pumpkin pie. We may eat more than usual, become a bit drowsy, take a nap, wake up and eat some more!
There has been an age-old tale that the turkey at Thanksgiving makes us sleepy, but is it true? Turkey contains tryptophan, which is an amino acid. The primary purpose of amino acids is to build protein, but they have many other functions. For example, tryptophan is used to make the B vitamin known as niacin. It is also a precursor to serotonin, a hormone that plays a role in mood and helps us feel calm. When eating lots of tryptophan-containing turkey, we feel relaxed and maybe even sleepy. It stands to reason, right? I’ll admit this one fooled me. Although turkey contains tryptophan, it also contains many other amino acids, and tryptophan isn’t used to make serotonin unless the body needs it.
Two mechanisms contribute to drowsiness after consuming a large meal. First, our brains secrete serotonin in response to carbohydrates, and there are plenty of those at the Thanksgiving table: mashed potatoes and gravy, dressing, cranberry sauce and a myriad of pies, just to name a few. Next, our blood sugar levels rise and insulin is secreted so blood sugar (glucose) can be taken to the cells. This process signals the body to slow down so food can be digested. The bottom line is we are sleepy because we’ve eaten a delicious meal full of carbohydrates. So, don’t blame the turkey when you can’t keep your eyes open because you’ve stuffed yourself!
Leanne McCrate is an award-winning dietitian based in Missouri. Her mission is to educate the public on sound, evidence-based nutrition. Do you have a nutrition question? Email her at [email protected]