‘Pie hole’, colloquial for one’s mouth, is believed to have evolved in the USA in the 1980s from the British expression ‘cake hole’ (coined in the mid 20th century). Pie hole refers to a mouth, as in: Shut your pie hole or, in this case: Put less in your pie hole.

Wednesday, November 27, 2013

Turkey and Tryptophan Got You Tired?

Every year since my first American Thanksgiving, I've heard people gobble about how turkey contains tryptophan and tryptophan makes you sleepy... Thus making it perfectly acceptable to take a nap post the annual Thanksgiving stuffing of the belly. Since it's that time of year, it seems a pertinent time to ponder this proposition. 

Tryptophan is one of the 20 amino acids (building blocks of protein). Turkey does contain tryptophan, but before you clap the gavel and declare this thought a fact, let's examine some other evidence.

Turkey isn't the only meat containing tryptophan; many meats do. In fact cheese, milk, eggs, tofu, seeds and nuts also do. Tryptophan on it's own, on an empty stomach may make one drowsy, but Thanksgiving dinners contain a number of sumptuous offerings beyond straight tryptophan containing turkey.

Tryptophan is used by the brain to synthesise serotonin, a sleep related neurotransmitter. Serotonin is ultimately metabolised by enzymes in the pineal gland to make melatonin, also sleep related. Think you have it pegged? Hold the phone...

Elevated blood levels of tryptophan doesn't equate to greater synthesis of melatonin. What we are not considering here is sweet. No really, it's dessert. After eating sugars/simple carbohydrates, the body releases insulin (the hormone responsible to storing excess glucose in the liver and muscles). Insulin also causes muscles to store branched chain amino acids. But tryptophan is an aromatic, not branched chain, amino acid.

What does it mean? After insulin's done its thing, there's a higher level of tryptophan hanging out in the blood. But again, this doesn't correspond with greater concentrations of melatonin synthesis.

The real cause of sleepiness after stuffing substantial amounts of scrumptious sustenance down one's pie hole? Exactly that, overeating. Stretching the small intestines induces sleepiness. More blood is needed there for digestion, therefore there is less blood elsewhere. Think "rest and digest", compared to "fight or flight".

We get to enjoy this holiday but once a year, why spoil it with a list of annoying tips? Here's a list of a different kind:
  • Enjoy the company of the ones you love
  • Be thankful to live in a country where there is peace, freedom and food
  • Take the time to savour and enjoy each bite
  • If you want to take a nap, don't blame the turkey
Happy Thanksgiving.

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