Quercetin, a flavonoid found in plants, is a potent antioxidant that can scavenge harmful free radicals in the body, possibly helping to prevent cell damage and chronic conditions, such as heart disease and cancer. Some natural healers advise quercetin supplements to promote health and treat a variety of conditions, including arthritis. Most scientific research has involved the effects of quercetin in the diet. While clinical studies on quercetin and arthritis are limited, a recent study showed some benefits of supplementary quercetin for osteoarthritis. Consult your doctor before using quercetin.
Features
Quercetin, or pentahydroxyflavone dihydrate, is found naturally in citrus fruits, apples, onions, parsley and green tea. Dark red and purplish fruits and berries that contain high levels of anthocyanins -- such as blueberries, Concord grapes, cherries and blackberries -- are excellent sources of quercetin. In addition to being used to treat arthritis, quercetin is employed to alleviate allergies, reduce the risk of cancer and heart disease, lower cholesterol levels, and treat interstitial cystitis and prostatitis.
Effects
Quercetin has anti-inflammatory, antihistamine and antiviral qualities. In animal and test tube studies, quercetin has anti-cancer properties, inhibiting the growth of breast, colon, ovarian and lung tumors. The University of Maryland Medical Center reports that people who eat diets high in quercetin-rich fruits and vegetables have a lower risk of some types of cancer. Some researchers believe that quercetin's antioxidant and anti-inflammatory effects may help treat both rheumatoid arthritis -- in which the immune system attacks the synovial membrane lining the joints -- and osteoarthritis, in which the cartilage between the bones deteriorates, causing the bones to rub against each other. UMMC notes that people with rheumatoid arthritis had fewer symptoms when they switched to a vegan diet featuring abundant amounts of fresh, raw berries and fruits rich in antioxidants.
Research
In an animal study published in 2006 in "Biological Pharmacology," both oral and intracutaneous dosages of quercetin decreased clinical arthritis symptoms in rats. Researchers noted that quercetin achieved an anti-inflammatory effect by inhibiting macrophage-derived cytokines as well as decreasing nitric oxide. They concluded quercetin was a potent anti-inflammatory therapeutic and preventive agent. In a study published in 2009 in "Bioscience, Biotechnology, and Biochemistry," researchers found that a combination of quercetin, chondroitin and glucosamine given for three months to patients with rheumatoid and osteoarthritis resulted in a significant improvement in pain symptoms in the osteoarthritis patients, as well as improvement in the synovial fluid properties. However, rheumatoid arthritis patients showed no improvement.
Usage and Considerations
According to Blue Shield Complementary and Alternative Health, quercetin may be taken in tablet or capsule form in dosages of 200 to 500 mg three times a day. Quercetin is sometimes combined with the anti-inflammatory enzymes bromelain and papain, which promote its absorption. Quercetin in turn promotes the absorption of vitamin C; BSCAH advises taking the supplements at the same time. Quercetin is generally considered safe, but it may cause headache and upset stomach. It can also interact with prescription drugs. Consult your doctor before taking quercetin; avoid quercetin if you are pregnant or breastfeeding.
References
- University of Maryland Medical Center: Quercetin; UMMC Staff; May 2009
- Blue Shield Complementary and Alternative Health: Quercetin
- "Biological Pharmacology"; Therapeutic And Preventive Properties of Quercetin In Experimental Arthritis Correlate With Decreased Macrophage Inflammatory Mediators; Maria Mamani-Matsuda, et al.; September 2006
- "Bioscience, Biotechnology, and Biochemistry"; Effects of an Oral Administration of Glucosamine-Chondroitin-Quercetin Glucoside on the Synovial Fluid Properties in Patients with Osteoarthritis and Rheumatoid Arthritis; H. Matsuno, et al.; February 2009
- Arthritis Foundation: Disease Center
