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Tryptophan and bananas

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Description: Why are bananas a better source of tryptophan that rice?
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bluegray
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« on: December 18, 2008, 15:02:47 PM »

Recently I read up on Tryptophan. Basically it is an essential amino acid that you need to make Serotonin. There are various sources on the web that claim bananas can help you sleep, cure depression ect. because it contains tryptophan, although it does not often say how much. It also does not often mention that almost all other protein rich foods also contain tryptophan.

According to the tryptophan wikipedia page, bananas contain 0.01g/100g and white rice contain 0.08g/100g. But I don't see white rice being promoted as an anti-depressant Huh?

Can anyone shed some light on the subject?
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AcinonyxScepticus
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« Reply #1 on: December 18, 2008, 15:59:38 PM »

There are various sources on the web that claim bananas can help you sleep, cure depression ect. because it contains tryptophan...

I didn't know tryptophan was an antidepressant (or people claimed it was).  Hmm, interesting.

Anyway, I'm here to impart second-hand wisdom, the best kind; someone else's research. Grin  I'm interested to see what other members have to say.

According to the Show Penn and Teller: Bullshit, in an episode about the thousands of insomnia curing claims, they stated that some people claim that tryptophan in milk causes sleepiness.  They then go on to explain that if you wanted to get a dose high enough to induce sleep, you would have to drink 21 full glasses of milk immediately before bed.  But here's the kicker; in order to have any measurable effect, tryptophan must be taken (in pure form) on an empty stomach!  All that milk counteracts the drowsiness you would gain from the tryptophan in the milk.  Same goes for turkey.

Anyone with more reliable sources?

James
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« Reply #2 on: December 18, 2008, 16:07:19 PM »

Scientific American: Does Turkey Make You Sleepy?

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« Reply #3 on: December 18, 2008, 16:17:48 PM »

enzymestuff.com: Enzymes & Serotonin
All meats contain the amino acid tryptophan, but they also contain much higher amounts of the competing amino acids. Turkey, milk, whole grains, bananas, eggs also contain tryptophan, but much lower amounts of the other competing amino acids. So foods in this last group have the net effect of increasing tryptophan levels and promoting more serotonin production.


Scientific American: Does Turkey Make You Sleepy?
Turkey and other protein-rich foods contain many amino acids, and tryptophan is the scarcest among them, Wurtman says. After a turkey dinner, several amino acids circulate through the bloodstream. To get into the brain they must be shuttled across the blood–brain barrier by specialized transport proteins. Like passengers trying to board a crowded bus, amino acids compete for rides on these transporters. Not only does tryptophan have paltry representation among the passengers; it also competes with five other amino acids for the same transporter. Aced out by other amino acids, tryptophan thereby has a tough time hitching a ride to the brain.

Taken in isolation, tryptophan would increase brain serotonin, Wurtman says, but no food source contains tryptophan in the absence of other amino acids.

So maybe bananas would perform differently from white rice...
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