Quercetin

written by Marina Zacharias

Quercetin is a flavanoid that serves as the backbone for many other flavanoids. It is consistently the most active of the flavanoids in experimental studies, and many medicinal plants owe much of their activity to their high quercetin content.

It is best known as an anti-inflammatory/anti-allergy agent. Because it stabilizes mast cell membranes and prevents the release of histamine and other inflammatory agents, it is often prescribed for food and inhalent allergies, asthma, excema, psoriasis, gout, and ulcerative colitis.

Due to its antioxidant effect, quercetin can inhibit inflammatory processes mediated by "leukotrienes" (inflammatory agents a thousand times more powerful than histamines), hyaluronidase (collagen-destroying enzymes), and lysosomal enzymes (other promoters of localized inflammation).

Quercetin can significantly decrease the accumulation of "sorbitol" in the lens of diabetic animals, effectively delaying the onset of cataracts. It is also indicated in diabetes for its ability to enhance insulin secretion, protect the pancreatic beta-cells from the damaging effects of free radicals, and inhibit platelet aggregation.

It functions like other bioflavonoids in enhancing the collagen network (structural integrity) of blood vessels, and is known for its antiviral activity.

Many flavonoids inhibit tumor formation, but again quercetin has consistently demonstrated significant antitumor activity against a wide range of cancers. Including squamous cell carcinoma; leukemia; and cancers of the breast, ovaries, colon, rectum, and brain. Unfortunately, there are no human studies to support the impressive results noted in animal and "in vitro" studies.

In nature it occurs in various fruits, vegetables, nuts, seeds, leaves, flowers, and barks. I use a high quality powder concentrate (300 mg. per capsule) made by Allergy Research. For best absorbtion it should be used in conjunction with a protein-digesting enzyme (for example: bromelain) in equal amounts.

Quercetin appears to be extremely safe to use. Carcinogenic and teratogenic studies in rats and rabbits have shown that it is without apparent side effects even when consumed in very large quantities (2,000 mg. per Kg. of body weight) for long periods of time (up to 2 years).

Unlike the citrus bioflavonoids, quercetin has no interaction with any drug. It can be used even during pregnancy.