Someone brought up Tryptophan, a chemical in turkey, and how it causes drowsiness. I claimed that I read it was a myth and nobody believed me. Being completely out numbered and without a source to back it up, I let it drop. Plus, it’s a pretty lame topic for debate. However, curiosity got the best of me and I couldn’t help but look it up as soon as I got back to the office.

The first site in my search was Wikipedia, which states the following:

One widely-held belief is that heavy consumption of turkey meat (as for example in a Thanksgiving or Christmas feast) results in drowsiness, which has been attributed to high levels of tryptophan contained in turkey.[47][48][49] While turkey does contain high levels of tryptophan, the amount is comparable to that contained in most other meats.[14] Furthermore, postprandial Thanksgiving sedation may have more to do with what is consumed along with the turkey, in particular carbohydrates and alcohol, rather than the turkey itself.

HowStuffWorks.com goes into more detail and even mentions a Tryptophan supplement that people were taking prior to it being banned by the FDA in 1990. Here’s what they have to say about the drowsiness issue:

Most likely, it’s the whole traditional Thanksgiving meal that can produce that after-dinner lethargy. The meal is quite often heavy and high in carbohydrates — from mashed potatoes, to bread, stuffing and pie — and your body is working hard to digest that food. After all, the average Thanksgiving meal contains 3,000 calories and 229 grams of fat [source: Meeks]. Also, if you drink alcohol with your dinner, you’ll likely feel its sedative effect, too.

Another great source for such information is Snopes.com. According to Snopes, the idea that eating turkey makes people drowsy is false.

In this instance, lore almost intersects with science. Turkey does contain tryptophan, an amino acid which is a natural sedative. But tryptophan doesn’t act on the brain unless it is taken on an empty stomach with no protein present, and the amount gobbled even during a holiday feast is generally too small to have an appreciable effect. That lazy, lethargic feeling so many are overcome by at the conclusion of a festive season meal is most likely due to the combination of drinking alcohol and overeating a carbohydrate-rich repast, as well as some other factors

Lastly, according information found on a search on the web site belonging to the National Turkey Federation, other foods, such as swiss cheese, or roasted pork loin actually contain more Tryptophan. The last paragraph there seems to sum it up best, specifically the last sentence:

In addition, a large holiday meal usually includes alcohol (which is a central nervous system depressant), overeating and a higher level of fatty foods (which all require a lot of energy to digest). Each of these factors contributes to after-dinner fatigue. In summary, the unusually large, multi-coursed, carbohydrate-rich meal eaten on Thanksgiving is more likely the cause of drowsiness. After all, in March, one does not get sleepy after eating a turkey sandwich.

So, here’s wishing happy and healthy holidays for everyone else!