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Dr. Yee Suk Kim and colleagues of The Catholic University of Seoul, South Korea, performed experiments in rats to evaluate the effectiveness of ginkgo against neuropathic pain, a common pain problem associated with herpes zoster, limb injury, or diabetes. Affected patients may feel severe pain in response to harmless stimuli like heat, cold, or touch.
Objective Evidence of Pain Reduction with Ginkgo
In the experiments, rats with neuropathic pain were treated with different doses of a standardized ginkgo biloba extract or with an inactive solution. Objective tests were performed to see how ginkgo affected neuropathic pain responses to cold and pressure.
For both cold and pressure stimuli, pain responses were significantly reduced in ginkgo-treated rats. This was so on before-and-after treatment comparisons and on comparison of ginkgo-treated versus placebo-treated animals.
The higher the dose of ginkgo extract, the greater the pain-relieving effect. Pain was reduced for at least two hours after ginkgo treatment.
The study provides no evidence as to how ginkgo works to reduce pain. Several mechanisms are possible, including antioxidant activity, an anti-inflammatory effect, or protection against nerve injury—perhaps in combination.
Many herbs and "alternative" drugs are commonly used without prescriptions for a wide range of purposes, despite a lack of scientific evidence for health claims. Ginkgo, one of the most popular herbal products, is widely used as a memory enhancer, among other purposes.
The new study provides the first scientific evidence that ginkgo has a real effect in reducing neuropathic pain. New treatments are needed for neuropathic pain, which does not always respond well to available treatments.
"It's still too early to stock up on ginkgo biloba if you have chronic pain," comments Dr. Steven L. Shafer of Columbia University, Editor-in-Chief of Anesthesia & Analgesia.
Many treatments that are effective in animals do not prove to be effective in humans, or prove to have unacceptable toxic effects when given to patients, Dr. Shafer reminds.
"However," he adds, "it is at least reassuring to know that scientists are investigating the properties of this ancient oriental herbal medication in an effort to determine what chemical constituents account for the many beneficial effects traditionally ascribed to it."