Quercetin Lowers Cortisol Levels


By Admin – Steroidal.com

Quercetin is another over the counter supplement that has gained popularity in recent years due to its various positive effects for athletes and bodybuilders. We blogged about Quercetin and its boosting on testosterone levels a little while back and now we’re going to discuss its effects on the catabolic hormone – cortisol.

Firstly just to recap, Quercetin is a plant pigment (flavonoid). It is found in many plants and foods, such as red wine, onions, green tea, apples, berries, Ginkgo Biloba, St. John’s wort, American elder, and some others. Quercetin is used medically in some areas of the world for the treatment of heart and circulatory conditions, heart disease, diabetes, hay fever, inflammation, asthma, cancer prevention and infection of the prostate. Due to its positive effects on testosterone, it is also used to enhance libido and athletic performance.

Today we’re going to look at another of Quercetins performance enhancing attributes, or its ability to lower cortisol levels. Cortisol is an adrenal hormone linked to times of stress and converts muscle tissue into sugars for energy. As bodybuilders or athletes, it’s a hormone we don’t want high all the time, and want to lower it in times of stress, such as post exercise, regardless of this being lifting weights or cardio.

The adrenal glands manufacture cortisol when the pituitary gland in the brain produces adrenal response to adrenocorticotropic hormone (ACTH). The pituitary only starts to do this when its been told to by the hypothalamus (the hormone control centre) secretes a hormone called CRF. Stress or depression will initiate the hypothalamus to secrete CRF, or when we wake up in the morning due to daylight. This explains why cortisol levels are high in the morning.

A recent Japanese study in 2009 at the University of Tokushima, looked at Quercetins effects on cortisol in rats. The rats were given Quesrcetin doses ranging from 10-50mg per kilogram of bodyweight, and to cause stress were submerged in water with only their heads showing. This test is called the Water Immersion Restraint (WIR). The rats were given their Quercetin dose thirty minutes before the WIR, which occurred for three hours. The Japanese researchers then examined the rat’s concentration of ACTH and cortisol.













As we can see, over time the Quercetin dose had the strongest suppression on cortisol levels. They then examined the rats brains they saw the Quercetin had inhibited the release of CRF. This then had an effect on cortisol levels.








The figure above shows the 50mg Quercetin dosage on CRF levels.

Its speculated that over time Quercetin accumulates in the rats brains and has more of a profound effect on cortisol levels. If this is true, a diet rich in Quercetin may mean less of a cortisol peak in times of stress from depression or physical activity.

Limitations are that this study is on rodents and large doses are used compared to human consumption from dietary intake. Supplementing with Quercetin is suggested due to its effects on testosterone, its anti-oxidant effects, various health benefits and may lead to a reduction in the manufacturing of stress-induced cortisol.


J Nutr Biochem. 2009 May 6. [Epub ahead of print].