Quercetin

Quercetin

Quercetin is a bioflavonoid found in high concentrations in onions, red wine, green tea and herbal extracts such as St. John's wort. Quercetin is frequently used in natural medicine because of antioxidant properties.

Efficacy

Preclinical data from in-vitro studies have shown anti-neoplastic activity in various types of cell lines. Quercetin has also shown to inhibit P53 gene mutations.

While there are few clinical studies assessing the anticancer actions of quercetin, evidence suggest antineoplastic effects of quercetin. For example, one such pilot trial assessed the effect of 60 mg of quercetin along with 1440mg curcumin daily in 5 patients with familial adenomatous polyposis (FAP). All 5 patients had a decrease in polyp number and size from baseline of 60.4% (P<0.05) and 50.9%(P<0.05) respectively after a mean of 6 months of treatment. There were no adverse effects reported.

Safety

Doses up to 1000 mg/day for up to 12 weeks have been shown well tolerated for human consumption.

Recommendations

Quercetin is used in naturopathic medical practice in doses of 500-3000 mg/day as post-chemotherapy adjuvant therapy to stabilize the P53 gene. Since it inhibits the release of histamine it is also prescribed for cancer patients with Ig E-mediated allergies. Courses of quercetin treatment may range from weeks to months. Some cancer patients, especially those with IgE-mediated allergies remain on low dose quercetin (500 mg/day) for years to manage allergies and prevent cancer recurrence.

http://depts.washington.edu/integonc/clinicians/act/quercetin.shtml