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Wednesday
Nov252009

It's Not the Turkey That Knocks You Out on Thanksgiving

Written by Tom Nikkola - Director of Nutrition & Weight Management

As far back as I can remember, our family always went to my Godparents house for Thanksgiving. Many of the great-tasting foods were the same from year to year and the day often unfolded much the same. We'd arrive, visit, have appetizers while watching one of the football games, eat dinner, dessert and then like magic; the adult men would fall fast asleep while the women visited in the kitchen. I can still see and hear my Godfather, Bill, snoring on the chair and my Dad sound asleep on the couch. Year after year, someone would say, "It's the turkey. That tryptophan puts you right to sleep."

Is there something special about turkey that really does knock you out, especially on Thanksgiving Day? Why is it that you can have turkey on other days and there's no effect? Is there something special about a baked turkey? Or is it possible the turkey really has nothing to do with the afternoon coma many people are put in following Thanksgiving dinner?

Turkey Isn't a "Sleeping Pill"

Turkey has gotten its reputation for inducing sleep based on the fact that it contains the amino acid l-tryptophan. The body uses tryptophan to produce the neurotransmitter serotonin. Serotonin is necessary to support rest, relaxation and restful sleep. Taking the amino acid tryptophan by itself may help support sleep, which could be where turkey got is sleep-inducing reputation. However, turkey is not really deserving of this reputation.

Turkey does not contain a significant amount of tryptophan compared to other foods, especially other protein-containing foods. The chart below shows the amount of tryptophan in a 3.6 ounce (100 gram) serving. As you can see, there are many other foods that have a higher concentration of tryptophan than turkey, yet none of these foods have the reputation for inducing sleep. Tryptophan competes with other amino acids in food to be absorbed into the brain. The small amount found in food is likely not enough to cause sleep, especially in the presence of the other amino acids. So if the turkey doesn't do it, what puts people to sleep?

Food

Tryptophan

(gr / 3.6 oz portion)

Dried Egg White

1.00

Dried Spirulina

0.93

Dried Atlantic Cod

0.70

Raw Soybeans

0.59

Parmesan Cheese

0.56

Caribou

0.46

Sesame Seed

0.37

Cheddar Cheese

0.32

Sunflower Seed

0.30

Pork Chop

0.25

Turkey

0.24

Chicken

0.24

Beef

0.23

Salmon

0.22

Atlantic Perch

0.21

Lamb Chop

0.21

Egg

0.17

White Wheat Flour

0.13

White Rice

0.08

Milk

0.08

Russet Potatoes

0.02

Adapted from the USDA nutrient database and Wikipedia

Then what causes me to fall asleep?

Considering a typical Thanksgiving Day meal, the list of foods likely includes: appetizers (typically high in carbohydrates), dinner rolls, stuffing, potatoes, gravy, turkey, green bean casserole, cranberries (usually sweetened) and of course, pumpkin pie. Although dinners vary from family to family, the majority of the foods will be fairly high in carbohydrate. The only food choice high in protein is the turkey, ham or something similar. Using my personal example from above, first come the appetizers. They're likely high in carbohydrates (yes, they're probably high in fat, too, but that won't impact blood sugar). Then comes the meal with a huge load of carbohydrates, followed by dessert, with more sugar and carbohydrates. Depending on where you get the information, Thanksgiving meals are between 3000-4500 calories.

So, once you're loaded up with carbohydrates, your blood-sugar goes up, up, up for a while and at some point it will come crashing down. That's when the lights go out. Along with falling blood-sugar, a couple of other things take place while you're sitting on the couch, more stuffed than the turkey ever could have been. Your intestines stretch out to handle the large volume of food, which can have the opposite impact of the "fight or flight" response on your nervous system. The huge feeding causes your nervous system to relax and induce sleep. Also, your digestive system needs more blood than normal to support the digestion of the meal. Since your digestive system needs it, the rest of your body gets less blood than normal, including your brain. Your body just knows that the best thing to do is make you sit still and burn as few calories as possible as it attempts to digest the massive meal.

Summary

Overfeeding is never really a healthy thing to do. The best thing to do is eat slowly, eat only one serving, and fill up more of your plate with turkey and vegetables. Eating more turkey will replace a lot of the other high-carb/high-fat foods around the table and fill you up faster. In fact, the turkey that you were told would put you to sleep may actually keep you from overdoing the food and falling fast asleep.

If you do choose to overindulge, be sure you get yourself to the gym the next day. If you average 300 calories burned per hour during exercise, you'll only need to workout for...fifteen hours to offset your meal. Fortunately, Life Time Fitness is open 24 hours a day! Happy Thanksgiving!

Resources:

Lieberman, H. Nutrition, brain function and cognitive performance. Appetite. November 2002

Coco Blaantyne. Does Turkey Make You Sleepy? Scientific American. November 21, 2007

Joanne Holden, Nutrition Data Laboratory, Agriculture Research Service. USDA National Nutrient Database for Standard Reference, Release 20. US Dept Agriculture

This article is not intended for the treatment or prevention of disease, nor as a substitute for medical treatment, nor as an alternative to medical advice. Use of recommendations in this and other articles is at the choice and risk of the reader.

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