Definition: "An ergogenic aid is any substance or phenomenon that enhances performance "
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30.05.2009 |
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Quercetin reduces cortisol peak after stress
A diet rich in flavonoids, or quercetin analogues, causes your body to make less of the muscle-destroying hormone cortisol after it has been exposed to psychological stress. Japanese researchers suspected this to be the case, and did tests on rats.
Study
The adrenals make cortisol, a sometimes annoying hormone that converts muscle proteins into sugar. When our forefathers were still roaming the prairies and often had to flee hungry sable-toothed tigers or woolly mammoths in a bad mood, long lasting cortisol peaks were no doubt extremely useful.
The adrenals manufacture cortisol when the pituitary gland in your brain produces ACTH. And the pituitary only starts to do this when the hypothalamus, another gland in the brain, produces the hormone CRF. Physical or psychological stress stimulates the hypothalamus to start making CRF. The first daylight has the same effect. That's why your cortisol level rises as the new day dawns.
The researchers caused major stress in their rat subjects by throwing them into water. The animals were submerged, with just their heads kept above water. Water Immersion Restraint is the name given to this practice. [WIR] After subjecting the rats to three hours of this, the researchers took them out of the aquarium and examined them.
Results
When the researchers examined the rats' brains, they saw that the single dose of quercetin had inhibited the release of CRF. The figure below shows the effect of the 50 mg dose. The researchers varied the amount of time the rats had to tread water.
Although the researchers used a high dose, they think that it's possible to benefit from this mechanism through diet as well. One hundred grams of onion can contain as much as 40 mg of quercetin. Other sources of quercetin are green tea, apples and broccoli. A supplement that contains a lot of quercetin is St John's Wort.
Mechanism
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