Text Size

Site Search powered by Ajax

Quercetin Supplements

Quercetin Supplements


Quercetin and rutin are bioflavonoids found in eucalyptus, the onion plant, and other sources. It is derived commercially from blue-green algae. Bioflavonoids (formerly termed vitamin P) are water soluble and composed of substances which often appear in fruit and vegetables as companions to vitamin C. Major bioflavonoids include citrin, hesperidin, rutin, flavones, and flavonals; although there are over a thousand altogether.

Method of Action

Bioflavonoids are essential for proper absorption and use of vitamin C. They assist vitamin C in keeping collagen in healthy condition, and are vital in their ability to increase the strength of the capillaries and to regulate permeability. These actions help prevent ruptures in the capillaries and connective tissues, and build a protective barrier against infection.

In countering allergic reactions, quercetin is reputed to inhibit, or block, histamine release.

Quercetin increases bile secretion, the detoxifying function of the liver, and has anti-inflammatory properties in animals. It is also effective against influenza viral infections on chick embryos and mouse tissue.

Therapeutic Approaches

Bioflavonoids are beneficial in the treatment of:

bleeding gums,
cirrhosis of the liver,
coronary thrombosis,
radiation sickness,
retinal hemorrhages,
respiratory infections and allergies like asthma, and
varicose veins.

Quercetin, specifically, is used therapeutically to decrease capillary fragility.

Toxicity Factors

The controversial Ames Test has caused quercitin to be labeled “mutagenic” but the validity is disputed, together with similar results for vitamin C itself and rutin.

Therapeutic recommendations tend to range between 125 and 500 mg. It will usually be taken before meals (i.e. three times a day) together with vitamin C and digestive enzymes (e.g. bromelain).



Airola, Paavo. How To Get Well. Phoenix, Arizona: Health Plus, 1974.

Carlotti-ME; Gallarate-M; Gasco-MR; Trotta-M Inhibition of lipoperoxidation of linoleic acid by five antioxidants of different lipophilicity. Pharmazie. 1994 Jan; 49(1): 49-52.

Elangovan-V; Sekar-N; Govindasamy-S. Chemopreventive potential of dietary bioflavonoids against 20-methylcholanthrene-induced tumorigenesis. Cancer-Lett. 1994 Nov 25; 87(1): 107-13.

Hendrickson-HP; Kaufman-AD; Lunte-CE. Electrochemistry of catechol-containing flavonoids. J-Pharm-Biomed-Anal. 1994 Mar; 12(3): 325-34.

Hirono, I. et al. Carcinogenicity examination of quercitin and rutin in ACI rats. Cancer Letters, 1981(13): 15-21.

Kirschmann, John D. Nutrition Almanac: Nutrition Search Inc. New York: McGraw-Hill. 1984.

Leung, Albert Y. 1980. Encyclopedia of Common Natural Ingredient used in Food, Drugs and Cosmetics. John Wiley and Sons, N Y. 409 pp.

Mahady-GB; Beecher-CW. Quercetin-induced benzophenanthridine alkaloid production in suspension cell cultures of Sanguinaria canadensis. Planta-Med. 1994 Dec; 60(6): 553-7.

Middleton, E. et al. Quercitin: an inhibitor of antigen-induced human basophil histamine release. J of Immunology,1981(127): 546-50.

Oyama-Y; Fuchs-PA; Katayama-N; Noda-K. Myricetin and quercetin, the flavonoid constituents of Ginkgo biloba extract, greatly reduce oxidative metabolism in both resting and Ca(2+)-loaded brain neurons. Brain-Res. 1994 Jan 28; 635(1-2): 125-9.

Ramanathan-R; Das-NP; Tan-CH. Effects of gamma-linolenic acid, flavonoids, and vitamins on cytotoxicity and lipid peroxidation. Free-Radic-Biol-Med. 1994 Jan; 16(1): 43-8.

Scambia-G et al. Quercetin potentiates the effect of adriamycin in a multidrug-resistant MCF-7 human breast-cancer cell line: P-glycoprotein as a possible target. Cancer-Chemother-Pharmacol. 1994; 34(6): 459-64.

Tezabwala-BU et al: Immunotoxicity of polyunsaturated fatty acids in serum-free medium. Immunopharmacol-Immunotoxicol. 1995 May; 17(2): 365-83.

Windholz, Martha, Susan Budavani, et. al. 1976. The Merck Index. Merck and Co., Inc. New Jersey.


Follow Applied Health on FaceBook Follow Applied Health on Twitter Follow Applied Health on Pinterest Follow Applied Health on YouTube

cruelty free - tested only on humans
We test only on humans