WEDNESDAY, Nov. 23, 2016 (HealthDay News) -- A nutrition expert is talking turkey to dispel some common myths about the focus of most Thanksgiving meals.

The most-repeated myth is that eating turkey makes you sleepy. While it does contain tryptophan -- an amino acid supplement that promotes sleep when taken alone on an empty stomach -- turkey also contains many other amino acids that are likely to limit the effects of tryptophan, said Judith Rodriguez. She is chair of the department of nutrition and dietetics at the University of North Florida.

After a large meal, your sleepiness is more likely due to blood being diverted from throughout the body, including the muscles and brain, to the stomach for digestion, Rodriguez explained in a university news release.

The second-most popular myth is that turkey skin is made up of bad "saturated" fat. Turkey skin doesn't contain just bad fats, it also has some good fats. But if you have some turkey skin, limit it to a small piece, Rodriguez advised.

Then there's the myth that says a USDA inspection sticker indicates that the bird is fresh and top grade. In fact, the government checks for wholesomeness and proper handling, and provides voluntary grading services. About 70 percent of inspected turkeys are graded. The grades are U.S. Grade A, B and C, Rodriguez said.

It's also a myth that you can check a whole turkey for "doneness" by pricking the leg to check for bleeding, she said.

Instead, you should use an oven-safe thermometer inserted in the lower part of the thigh or in the center of the stuffing. A temperature of 180 degrees in the thigh and 165 degrees in the breast or stuffing indicates doneness, Rodriguez said.

And finally, the myth of origin. Turkeys are not from Turkey, Rodriguez said.

"Of the two wild species of turkey, one is indigenous to the areas from Canada to Mexico, and the other is indigenous to the areas from the Yucatan to Guatemala. The Aztecs ate domesticated turkeys. Turkeys were found in the New World and taken back to Spain, from where they quickly spread throughout Europe and other regions. The bird was introduced to England in the 1500s, then the Pilgrims brought it back to North America in the 1620s on the Mayflower, not realizing that was indeed, the turkey's point of origin," she explained in the news release.

More information

Mass.Gov offers more Thanksgiving health and safety tips.