Quercetin

You may have heard of the French paradox. The French diet is very high in fat and cholesterol (just think of pt de fois gras and croissants), yet France has one of the worlds lowest rates of heart disease. One theory for this discrepancy is that another major player in the French diet—red wine—protects the arteries of the heart. A natural antioxidant found in red wine, quercetin protects cells in the body from damage by free radicals (naturally occurring but harmful substances). Heart disease and high cholesterol are thought to be at least partly caused by free radical damage to blood vessels, so it makes sense that quercetin might help protect against heart attacks and strokes. Quercetin belongs to a class of water-soluble plant coloring agents called bioflavonoids, a type of nutrient that were learning more about all the time. Although they dont seem to be essential to life, its likely that we need them for optimal health. Another intriguing finding is that quercetin may help prevent immune cells from releasing histamine, the chemical that initiates the itching, sneezing, and swelling of an allergic reaction. Based on this very preliminary research, quercetin is often recommended as a treatment for allergies and asthma.

Quercetin is not an essential nutrient. It is found in red wine, grapefruit, onions, apples, black tea, and, in lesser amounts, in leafy green vegetables and beans. However, to get a therapeutic dosage, you'll have to take a supplement. Quercetin supplements are available in pill and tablet form.

A typical dosage is 200 to 400 mg 3 times daily. Quercetin may be better absorbed if taken on an empty stomach.

The most popular use of quercetin is as a treatment for allergic conditions such as asthma, hay fever, eczema, and hives. This use is based on test-tube research showing that quercetin prevents certain immune cells from releasing histamine, the chemical that triggers an allergic reaction. It also may block other substances involved with allergies. But we have no evidence as yet that taking quercetin supplements will reduce your allergy symptoms. Prostatitis is an inflammation or infection of the prostate gland. In some cases, no cause can be discovered. The condition causes chronic pain and difficulty with urination, and is sometimes called chronic pelvic pain syndrome. Conventional treatment for this condition is often unsatisfactory. According to a 1-month double-blind placebo-controlled trial of 30 men with chronic pelvic pain, quercetin at a dose of 500 mg twice daily might be helpful. A small double-blind placebo-controlled trial found that a supplement containing quercetin reduced symptoms of interstitial cystitis. Very preliminary evidence also suggests that quercetin might help prevent heart disease and strokes. Test-tube and animal research also suggests that quercetin might have anticancer properties. An animal study found that quercetin might protect rodents with diabetes from forming cataracts. Another intriguing finding of test-tube research is that quercetin seems to prevent a wide range of viruses from infecting cells and reproducing once they are inside cells. One study found that quercetin produced this effect against herpes simplex, polio virus, flu virus, and respiratory viruses. However, none of this research tells us whether humans taking quercetin supplements can hope for the same benefits. Much more research needs to be done on the use of quercetin for these conditions.

Quercetin appears to be quite safe. However, at one point concerns were raised that it might cause cancer. Quercetin fails a standard laboratory test called the Ames test, which is designed to identify chemicals that might be carcinogenic. However, a bad showing on the Ames test does not definitely mean a chemical causes cancer. Other evidence suggests that quercetin does not cause cancer, and may in fact help prevent cancer. However, one highly preliminary study suggests that quercetin combined with other bioflavonoids in the diet of pregnant women might increase the risk of infant leukemia. Maximum safe dosages for young children, women who are pregnant or nursing, or those with serious liver or kidney disease have not been established.