By Beth Israel Deaconess Medical Center Correspondent
It's a familiar scene: Gravy-stained plates piled high in the sink, pumpkin pie browning in the oven, trails of cranberry sauce splattered across the floor, and in the next room, serenaded by the sounds of football and an over-indulgent uncle, your family teeters at the brink of sleep.
What's the deal? You wonder. Is all this yawning the effect of tryptophan in turkey?
The claim, though commonly referenced and widely believed, is more fiction than fact.
Yes, turkey is a source of tryptophan — an essential amino acid that's necessary for a healthy diet — but so are many other common foods: chocolate, oats, fish, peanuts. And for tryptophan to have any noticeable effect on the brain, it has to be consumed by itself, on an empty stomach. When other amino acids are present, tryptophan has to compete to pass through the formidable blood-brain barrier, something this heavy amino acid is not particularly good at.
The exception to this occurs when you eat a small, carbohydrate snack several hours after eating foods high in tryptophan. A slice of pie after turkey would do the trick. In this case, the carbohydrates help clear the path as they carry stored tryptophan through the blood-brain barrier, where it gets converted to serotonin and eventually melatonin, an important chemical in the process of sleep.
While misrepresented as a sleeping potion, tryptophan has many beneficial functions that are necessary for daily health. For example, your body uses it to make niacin, a type of B vitamin that's important for digestion, skin health, and nervous system performance. It's also proven to be a key component in regulating one's mood and sense of well-being.
So while you might feel tired with a tummy full of turkey this Thanksgiving, the real culprit is likely overeating, not tryptophan. Although it might have something to do with that talkative uncle too.
Above content provided by Beth Israel Deaconess Medical Center. For advice about your medical care, consult your doctor.
Posted December 2016
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