Quercetin, a member of a class of organic compounds called flavonoids, is found mainly in citrus fruits, apples, onions, teas and red wine. Scientists have studied it in cell culture experiments and found that it has good anti-inflammatory and antioxidant properties. Neuropathy is a condition involving damage to the peripheral nerves, those that extend outward from the brain and spinal cord. Studies in humans and mice indicate that quercetin may have therapeutic value in the treatment of neuropathy.
Nature of Quercetin
Quercetin is a flavonoid -- polyphenolic organic compounds synthesized by plants. It serves as a pigment that imparts its reddish color to foods such as apples, grapes and red onions. Its polyphenolic chemical structure makes it a potent antioxidant, and it may also have anti-inflammatory and antihistamine properties. Scientists have studied quercetin for biological activities related to heart disease, cancer, prostatitis, allergies and diabetic neuropathy. Most of what is known about these biological activities comes from laboratory cell culture studies, animal studies and small clinical trials. A full understanding of the therapeutic value of quercetin requires results from placebo-controlled, large-scale human clinical trials.
Neuropathy Defined
Neuropathy, also called peripheral neuropathy, is the term doctors use to describe damage to the peripheral nerves. These nerves send signals from various parts of the body to the spinal cord, which then transmits the signals to the brain. They also carry nerve impulses from the brain and spinal cord to direct muscle movement and organ function. Peripheral nerves thus control involuntary body functions such as breathing, heartbeat and digestion. Symptoms of neuropathy include deficiencies in coordination, muscle control and balance, trouble swallowing and feelings of pain, numbness, tingling or burning that start in the feet and may later involve the hands, arms and legs. One of the most common causes of neuropathy is uncontrolled diabetes. Other causes include genetic predisposition, inflammation, malignancy and infections.
Quercetin in Mice
In the September 2003 issue of "Progress in Neuropsychopharmacology and Biological Psychiatry," researchers reported the use of a mouse model of diabetes to demonstrate the potential therapeutic value of quercetin for relief of the pain of diabetic neuropathy. The scientists induced diabetes in the mice and found they showed hyperalgesia, an extreme sensitivity to pain. After the mice were given an oral dose of quercetin, they showed a significant increase in their threshold for pain.
Clinical Trial of Quercetin
Reporting in the September 2005 issue of the "Journal of Diabetes and Its Complications," scientists described the results of a clinical trial involving topical admininstration of quercetin to 34 men and women with diabetic neuropathy affecting their feet. A group of patients rubbed the quercetin preparation onto their feet three times a day for four weeks and another group applied placebo. The researchers found that the quercetin group experienced reduced pain and numbness and a better quality of life. Side effects of the treatment were mild and posed no serious problems.
References
- University of Maryland Medical Center; Quercetin; May 2009
- American Cancer Society; Quercetin; November 2008
- Better Medicine: Neuropathy
- "Progress in Neuropsychopharmacology and Biological Psychiatry"; Quercetin, a Bioflavanoid, Attenuates Thermal Hyperalgesia in a Mouse Model of Diabetic Neuropathic Pain; Muragundla Anjaneyulu, et al.; September 2003
- "Journal of Diabetes and Its Complications"; A Multicenter, Double Blind, Safety Study of QR-333 for the Treatment of Symptomatic Diabetic Peripheral Neuropathy; Carolyn LeFante, et al.; September 2005
