Quercetin is a potent antioxidant and has anti-inflammatory activity, protecting cellular structures and blood vessels from the damaging effects of free radicals. It improves blood vessel strength. Quercetin inhibits the activity of catechol-O-methyltransferase that breaks down the neurotransmitter norepinephrine. This effect may lead to elevated levels of norepinephrine and an increase in energy expenditure and fat oxidation. It also means quercetin acts as an antihistamine leading to relief of allergies and asthma. As an antioxidant, it reduces LDL cholesterol and offers protection from heart disease.

1. Quercetin is used for treating conditions of the heart and blood vessels including "hardening of the arteries" (atherosclerosis), high cholesterol, heart disease and circulation problems.

2. Quercetin is also used to increase endurance and improve athletic performance.

3. Quercetin is also used for diabetes, cataracts, hay fever, peptic ulcer, schizophrenia, inflammation, asthma, gout, viral infections, chronic fatigue syndrome(CFS), preventing cancer and for treating chronic infections of the prostate.

4. Quercetin has anticancer activity, inhibits PI3-kinase activity and slightly inhibits PIP Kinase activity, reduces cancer cell growth via type II estrogen receptors.