GINKGO
Ginkgo biloba

Location
Against the south side of the Medical and Dental Building.

Description
Ginkgo biloba, also called maidenhair tree, is a tall, deciduous tree with fan-shaped leaves that are long-stemmed and two-lobed (hence the species name biloba).  The leaves turn golden in autumn. The yellow fruits contain a hard seed (Weiss 1998).

History
Ginkgo originated two hundred million years ago, and is the only surviving member of its genus (Blumenthal 2000). Ginkgo has been grown in China for thousands of years and in Japan for about 1,000 years. Ginkgo was introduced to Europe in the eighteenth century.  The first tree to be planted in North America was in 1784 in a garden near Philadelphia (Kiple 2000).

Ginkgo seeds (also called nuts) have been used in traditional Chinese medicine for thousands of years. Roasted seeds, devoid of pulp, are a delicacy in Japan and China.  Roasted, grilled, steamed or boiled nuts are also used in Asian soups, appetizers, and desserts.  Boiled, dried, canned, or candied ginkgo seeds are available in Asian food stores (Kiple 2000).

Current Medicinal Uses
More than four hundred scientific studies have been conducted on extracts or components of ginkgo leaf in the past 30 years.  Ginkgo biloba extract (GBE) is popular in Europe, the United States, and other parts of the world; it is used to aid memory and circulatory problems in the elderly (Blumenthal 2000).  Clinical trials support the present use of GBE for improving microcirculatory disorders and dementia.

A systematic review of nine randomized, double-blind, and placebo-controlled studies also concluded that ginkgo is more effective for dementia than placebo (Ernst 1999b). A meta-analysis of eight placebo-controlled, double-blind randomized controlled trials found that ginkgo significantly increased pain-free walking distance in patients with intermittent claudication (Pittler 2000).

A review of randomized controlled trials of ginkgo for tinnitus found that ginkgo was significantly better than placebo in four of five studies; all of the studies that found a benefit used daily doses of 120-160 mg (Ernst 1999a). The largest trial to date (not included in the above review), a double-blind, placebo-controlled trial of 1121 healthy people with tinnitus, found no difference between groups treated with placebo or a standardized extract (LI 1370, Lichter Pharma) three times daily for twelve weeks (Drew 2001). Two trials of ginkgo in combination with laser treatment found no benefit of ginkgo as adjunctive treatment for tinnitus (Plath 1995, Wedel 1995).

Ginkgo leaf and ginkgo leaf extracts have been used to treat many other conditions, including preventing acute mountain sickness, and treating sexual dysfunction caused by serotonin reuptake inhibitors (Blumenthal 2000). Topically, ginkgo leaf extracts have been used on wound dressings.

Ginkgo seeds are used as a food and also in traditional Chinese medicine as an expectorant, to treat wheezing, and to treat urinary tract conditions (Bensky 1986).

Adverse Effects
Ginkgo seeds should be boiled before eating, as they contain ginkgotoxin (4’-O-methylpyridoxine), an anti-vitamin B6 compound, which is inactivated by boiling. During food shortages in China and Japan, overconsumption of ginkgo seeds resulted in a syndrome called Gin-nan sitotoxism, with a 27% mortality rate (Arenz 1996). The leaves contain very small amounts of ginkgotoxin, which is much more concentrated in the seeds.  Ginkgotoxin has been linked to seizures (Kajiyama 2001, Granger 2001).

Contact with the fruit pulp should be avoided, as it contains ginkgolic acid, which is similar to poison ivy allergens. Contact with the fruit has caused contact dermatitis (Fugh-Berman 2003).

References
Arenz A, Klein M, Fiehe K et al. Occurrence of neurotoxic 4’-)-methylpyridoxine in Ginkgo biloba leaves, Ginkgo medications and Japanese Ginkgo food. Planta Medica 1996;62:548-551.

Bensky D, Gamble A. Chinese Herbal Medicine Materia Medica.  Eastland Press, Seattle,1986:560-561.

Blumenthal M, Goldberg A, Brinckmann J, ed. Herbal Medicine. Integrative Medicine Communications, Newton, 2000:160-169.

Drew S, Davies E.  Effectiveness of Ginkgo biloba in treating tinnitus: double-blind, placebo controlled trial.  BMJ 2001;322:73-75.

Ernst E, Stevinson C. Ginkgo biloba for tinnitus: a review. Clin Otolaryngol. 1999a;24(3):164-7.

Ernst E, Pittler MH.  Ginkgo biloba for dementia: a systematic review of double-blind, placebo-controlled trials.   Clin Drug Invest 1999b;17(4):301-308.

Fugh-Berman A. The 5-Minute Herb and Dietary Supplement Consult. Lippincott, Williams, and Wilkins, Baltimore, 2003:148-149.

Granger AS.  Ginkgo biloba precipitating epileptic seizures. Age Ageing. 2001 Nov;30(6):523-5.

Kajiyama Y, Fujii K, Takeuchi H, Manabe Y.  Ginkgo seed poisoning. Pediatrics. 2002 Feb;109(2):325-7.

Kiple KF, Ornelas KC, ed. The Cambridge World History of Food. Cambridge University Press, Cambridge, 2000.

Pittler MH, Ernst E.  Ginkgo biloba extract for the treatment of intermittent claudication: a meta-analysis of randomized trials.Am J Med. 2000 Mar;108(4):276-81.

Plath R, Oliver J. Results of combined low-power laser therapy and extracts of Ginkgo biloba in cases of sensorineural hearing loss and tinnitus. Adv Otorhinolaryngol 1995;49:101-104.

Wedel Hv, Calero L, Walger M et al. Soft-laser/Ginkgo therapy in chronic tinnitus. Adv Otorhinolaryngol 1995;49:105-106. 

Weiss RF. Herbal Medicine. Beaconsfields Publishers LTD, Beaconsfield, 1988.