June 27, 2016

Quercetin

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What other names is Quercetin known by?

3,3',4'5,7-Penthydroxyflavone, Bioflavonoid, Bioflavonoid Complex, Bioflavonoid Concentrate, Bioflavonoid Extract, Bioflavonoïde, Bioflavonoïde de Citron, Bioflavonoïdes de Citron, Citrus Bioflavones, Citrus Bioflavonoid, Citrus Bioflavonoids, Citrus Bioflavonoid Extract, Citrus Flavones, Citrus Flavonoids, Complexe de Bioflavonoïde, Concentré de Bioflavonoïde, Extrait de Bioflavonoïde, Extrait de Bioflavonoïdes de Citron, Flavones de Citron, Flavonoid, Flavonoïde, Meletin, Mélétine, Quercetina, Quercétine, Sophretin, Sophrétine.

What is Quercetin?

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 others. Buckwheat tea has a large amount of quercetin. People use quercetin as a medicine.

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

Possibly Effective for...

  • Prostate pain and swelling (inflammation). Taking quercetin by mouth seems to reduce pain and improve quality of life, but doesn't seem to help urination problems in men with ongoing prostate problems that aren't due to infection.

Insufficient Evidence to Rate Effectiveness for...

  • Heart disease. Some research suggests that eating foods rich in quercetin, such as tea, onions and apples, can reduce the risk of heart disease-related death in elderly men. However, other early research suggests that taking a daily quercetin supplement does not improve heart disease risk factors.
  • High cholesterol. Short-term use of quercetin supplements does not seem to lower "bad cholesterol" (low-density lipoprotein (LDL) cholesterol), lower total cholesterol, or raise "good cholesterol" (high-density lipoprotein (HDL) cholesterol).
  • High blood pressure. Some research suggest that 365mg of quercetin aglycone twice daily produces a small (5-7 mmHg) decrease in blood pressure in people with untreated, mild high blood pressure. It's not known yet how important this is.
  • Exercise-induced respiratory infections. Developing research shows that taking 500 mg of quercetin twice daily for 3 weeks before, and continuing during 3 days of extended, intense cycling reduces the number of upper respiratory infections in the 14 days following the heavy exercise.
  • Kidney transplantation. Some research suggests that a combination of 20 mg of quercetin and 480 mg of curcumin taken once or twice daily, starting within 24 hours of kidney transplantation and continuing for one month, in combination with anti-rejection drugs, improves early function of the transplanted kidney.
  • Lung cancer. Some research suggests that consuming high amounts of quercetin in the diet might reduce the chance of developing lung cancer, especially in men who smoke.
  • Ovarian cancer. One study found no link between quercetin intake from the diet and the chance of ovarian cancer.
  • Pancreatic cancer. Some research suggests that eating high amounts of quercetin in the diet might reduce the chance of developing pancreatic cancer, especially in men who smoke.
  • Exercise performance.
  • "Hardening of the arteries" (atherosclerosis).
  • Diabetes.
  • Cataracts.
  • Hay fever (allergic rhinitis).
  • Stomach and intestinal ulcers.
  • Schizophrenia.
  • Pain and swelling (inflammation).
  • Asthma.
  • Gout.
  • Viral infections.
  • Chronic fatigue syndrome (CFS).
  • Cancer.
  • Other conditions.
More evidence is needed to rate quercetin for these uses.

Natural Medicines Comprehensive Database rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, and Insufficient Evidence to Rate (detailed description of each of the ratings).


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