Ginkgo Does Not Cause Bleeding
Despite several well-publicized case reports linking the use of Ginkgo biloba extract (ginkgo) to episodes of severe bleeding, this herb does not appear to increase the risk of bleeding, according to a new study in Clinical and Laboratory Haematology (2003;25:251–3).
Ginkgo is a widely used herb that has shown beneficial effects in the treatment of various age-related problems, including loss of memory, hardening of the arteries (intermittent claudication), and macular degeneration. Ginkgo also has shown promise as a treatment for erectile dysfunction, vertigo, ringing in the ears (tinnitus), and vitiligo (a depigmenting skin disorder). In addition, it has recently been found to prevent altitude sickness in mountain climbers.
The use of ginkgo has been clouded, however, by several case reports of spontaneous bleeding, sometimes severe, in people taking the herb. The possibility that ginkgo can promote bleeding is biologically plausible, since it inhibits a substance in the body known as platelet-activating factor, which plays a role in blood clotting. On the other hand, many other nutrients and herbs inhibit various components of the blood-clotting system without actually increasing the risk of bleeding. Because millions of people take ginkgo and because spontaneous bleeding does occur occasionally for no apparent reason, it is possible that the case reports linking ginkgo and bleeding were just a coincidence.
In the new study, 32 healthy young male volunteers were randomly assigned to receive a placebo or a standardized extract of ginkgo in doses of 120, 240, or 480 mg per day for 14 days. The highest dose of ginkgo used in this study was four times the amount typically recommended for prevention and treatment of various health conditions. Compared with the placebo, none of the doses of ginkgo had any effect on platelet function or other measures of blood clotting.
While this study suggests that taking ginkgo does not increase the risk of abnormal bleeding, it is conceivable that ginkgo taken in combination with blood-thinning medication, such as aspirin or warfarin (Coumadin), could cause a problem. Some of the case reports linking ginkgo to bleeding were in people who were also taking blood-thinning drugs. People using these medications should, therefore, consult a doctor before taking ginkgo. It is also possible that the bleeding episodes associated with ginkgo were due to idiosyncratic reactions to the herb in susceptible individuals. Additional studies, using larger numbers of participants and older age groups should be done in order to confirm the safety of ginkgo.
Alan R. Gaby, MD, an expert in nutritional therapies, testified to the White House Commission on CAM upon request in December 2001. Dr. Gaby served as a member of the Ad-Hoc Advisory Panel of the National Institutes of Health Office of Alternative Medicine. He is the author of Preventing and Reversing Osteoporosis (Prima, 1994), and co-author of The Natural Pharmacy, 2nd Edition (Healthnotes, Prima, 1999), the A–Z Guide to Drug-Herb-Vitamin Interactions (Healthnotes, Prima, 1999), Clinical Essentials Volume 1 and 2 (Healthnotes, 2000), and The Patient’s Book of Natural Healing (Prima, 1999). A former professor at Bastyr University of Natural Health Sciences, in Kenmore, WA, where he served as the Endowed Professor of Nutrition, Dr. Gaby is the Chief Medical Editor for Healthnotes, Inc.
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