Every year, around Thanksgiving and Christmas, the news media are filled with stories about how eating a turkey dinner will make you sleepy due to tryptophan in the turkey. In actuality, while it makes a fun news story (and a plausible excuse), it's nonsense. Here's why:
Tryptophan is an essential Amino Acid. Tryptophan is a component of many plant and animal proteins, and a normal part of the diet that humans must get from outside sources. It is a precursor (starting material) for serotonin from which our brains make serotonin, which is then used to calm you down and make you sleepy. Tryptophan also helps in niacin (B vitamins) production.
Foods that are considered sources of tryptophan are dairy products, beef, poultry, barley, brown rice, fish, soybeans, and peanuts.
L-tryptophan, in substantial quantities, is a natural sedative. It is normally found in turkey meat, and many people believe it to be the cause of a sleepiness common after a Thanksgiving feast.
L-tryptophan was a very popular sleeping aid in the United States until recently, and was also used for premenstrual syndrome and depression. The FDA (Food and Drug Administration) removed it off the market in 1990 because of a sudden outbreak of eosinophilic-myalgia syndrome among people who had taken the supplement. About 5,000 people got sick and 27 died.
The ailment Eosinophilic-myalgia is characterized by muscle pain, weakness, and joint pain. It is serious and sometimes fatal. An investigation into the connection with L-tryptophan traced the problem to a contaminated batch of the supplement made by a Japanese company, Showa Denko KK, which had changed its fermentation process to incorporate genetically engineered bacteria, and had also lessened the amount of charcoal it used to purify the product. Nevertheless, the FDA did not relax its ban, reasoning that it's still not clear whether manufacturers can make a product that isn't toxic. However, L-tryptophan is still available by prescription in Canada.
Of course, this does NOTt mean that the tryptophan that occurs naturally in foods, like turkey is harmful! The tryptophan that occurs naturally in foods, like turkey, is perfectly safe.
Now, back to our original question. Does the tryptophan in turkey make you sleepy after eating a big Thanksgiving turkey dinner?
Sorry to say, that if you're looking for the sedative effect, it's unlikely you'll get it from eating meats like turkey. L-tryptophan doesn't act on the brain unless you take it on an empty stomach with no protein present. Additionally, the levels found in a turkey dinner are far, far too low to have such an effect. So, even though the mass media, CNN and Fox like to hype it and blame post holiday meal sleepiness on the turkey dinner... that's just a catchy sound-bite.. not the reality. The trypophan isn't to blame for the sudden drowsiness that hits right after the meal when the football games come on, and the dishes are waiting!
It's more likely due to the combination of drinking alcohol and overeating - not just turkey, but also mashed potatoes, ham, creamed onions, cranberries, sweet potatoes, peas, stuffing (or dressing, if you prefer), carrots, bread, pies, and whipped cream, (and how many beers did you have???) - all of which have the effect of pulling the blood away from your brain to help your digestive tract do it's work, and the sugar/insulin effect.
On the bright side, more evidence suggest that caffeine is not only not bad for you; it actually helps many brain functions, alertness, learning, memory and countering Alzheimers... so as long as you don't become a total, jittery addict... have a cup of coffee or tea! (and switch to green tea if you really want to claim additional health benefits! )!
What can you do? Meals heavy in carbs such as simple sugars and simple starches will indeed cause an insulin effect and trigger sleepiness a short while later. So eat a balanced meal, more fresh or steamed vegetables, lean proteins and don't pig out - too much - or just plan on a nap.
But take care of the dishes first... or you'll be seeing an ant invasion!