You always hear about tryptophan around Thanksgiving time. Folks warn that that getting too much turkey (one of the most well-known sources) puts you in a “food coma.” Is it really to blame for that post-dinner snooze?

What Is It?
This specific amino acid (a.k.a. a building block for protein) is considered “essential,” which means your body can’t make it on its own — you can only get it from food. All types of protein-rich foods are made of a combination of different amino acids. Tryptophan is important because it helps the body produce two must-haves: the B-vitamin niacin and the chemical serotonin. Like many other nutrients, supplements exist, but research has found these can cause some very dangerous side effects. So, as usual, stick to the safest version — tryptophan found naturally in your food!

Why Is It Good For You?
Tryptophan is one way that our bodies can get niacin; plus, it’s important for energy metabolism, our digestion and maintaining healthy skin.

What About That “Turkey Makes You Sleepy” Story?
That food myth has to do with tryptophan’s help in forming serotonin, which is involved in sleep regulation, appetite control and mood. The reality is that you’d have to eat tryptophan alone and on an empty stomach (not likely on Thanksgiving) in order for it to make you feel sleepy. Because foods that contain tryptophan also contain other types of amino acids, that holiday turkey isn’t what’s making you tired. In fact, turkey’s tryptophan content isn’t even as high as it is in chicken and cheese.

The reality: Overeating, drinking alcohol and consuming a high-fat meal (which takes more time and energy to digest) are more likely the causes for that Thanksgiving afternoon nap.

Where Can I Find It?
Other than turkey, here are some of the major sources of tryptophan:
Cheese
Chicken
Eggs
Fish
Mushrooms
Nuts
Peanut butter
Pork
Pumpkin (and pumpkin seeds)
Spinach
Tofu
Turkey
Turnips

See a lot of familiar Thanksgiving dishes lurking in that list?