Of course it is. Tryptophan (L-Trpyptophan) is actually one of nine essential amino acids that your body needs and that you must get externally. Turkey is a very good source and that is a very good thing.
Most people blame Tryptophan for the sleepiness you feel after a good Thanksgiving meal. It does contribute but its it not quite that simple. Tryptophan is in part responsible for generating melatonin, which is helps the body regulate sleep. But some experts say there is not enough tryptophan in turkey to make it to your brain to really generate enough melatonin to knock you out.
When you pig out on a huge meal, like you know you are going to do for Thanksgiving, its the carbohydrates that make you sleep, since processing them requires tryptophan (previously stored in this case) which, as mentioned, generates melatonin, which regulates sleep. So in reality, its the candied yams and apple pie with ice cream that are making you sleepy, not the turkey.
For you anti-aging practioners, like me (see Tim vs. Aging) you might be interested in the fact that tryptophan is instrumental in the body in producing niacin, which process to NMN, which processes to NAD+, which is what helps cell reproduce more faithfully.
But if you have a normal diet (i.e. not a vegan or other assorted grasseater…) you won’t have a problem keeping an adequate supply of tryptophan. Chicken, eggs, cheese, fish and peanuts are also very good sources.
And Happy Thanksgiving!