What Is It?

Ginkgo refers to preparations of the leaves of the Ginkgo biloba or maindenhair tree, for therapeutic purposes. 2 Ginkgo is one of the most popular herbal preparations in the US and Europe, due to its effectiveness for improving cognitive function. Ginkgo is the subject of over 400 studies, and demonstrates benefit in improving function in cases of impaired cognitive ability, poor circulation to the lower legs, vertigo and tinnitus. 3,4

Ginkgo is available in either non-standardized form or as a standardized extract containing 24% flavone glycosides and 6% terpene lactones. The standardized extract has shown efficacy in human and other studies. 2,3,4 Ginkgo has gained broad acceptance among the general public, and broad distribution throughout the health food sector, drug stores and supermarkets, due to the outstanding body of science supporting its use.

Medicinal History

According to botanist Steven Foster, Ginkgo was once common in North America and europe, but became largely extinct during the ice age, surviving only in China. 5 Ginkgo is mentioned in the oldest Chinese herbal the Shen Nong Ben Cao Jing. 6 Ginkgo leaf was mentioned in the Dian Nan Ben Cao, or Pharmaceutical Natuiral History of Southern Yunnan, published in 1436. Ginkgo was also mentioned in a subsequent Chinese herbal published in 1505, Ben cao Pin Hui Jing Yao, or Essentials of the Pharmacaopoeia Ranked According to nature and Efficacy. In Chinese traditional medicine, ginkgo leaves are known to benefit the brain. 5

Ginkgo made its passage from China and Japan to Europe around 1727. 7 In 1771 the famous botanist Linnaeus gave ginkgo the official name Ginkgo biloba. The first ginkgo tree was introduced to the United States in 1784. Ginkgo became a widely appreciated ornamental that can tolerate a wide range of growing conditions, including urban pollution.

Modern research into the beneficial properties of Ginkgo biloba began in earnest in the 1970’s. The Willmar Schwabe company of gerrmany has largely led the scientific charge, and has been the primary entity responsible for bringing to light the many and varied beneficial properties of Ginkgo biloba extract. Today Ginkgo biloba extract products are found in health food stores, pharmacies and supermarkets, and Ginkgo biloba is one of the best-selling botanicals in the natural pharmacy.

Habitat & Cultivation

Ginkgo biloba is native to China, specifically the area of Tianmushan, where the oldest known specimens of ginkgo exist. The tree is grown as an ornamental in the United States, Southeast Asia, Japan, Australia and France. 2 For the manufacture of extracts, Ginkgo biloba is cultivated in Japan, China, Korea, South Carolina and Maryland in the US, and France. 8,9 For the purpose of making botanical supplements, the leaves are picked at maturity and are extracted.

How It Works

Ginkgo biloba extract has been shown to improve tolerance to reduced oxygen levels in brain tissue due to impaired circulation; inhibit cerebral edema (swelling) due to trauma or toxicity, and accelerate its regression; reduce edema (swelling) in the retina of the eye and reduce cellular lesions in the retina; inhibit the reduction of certain important brain chemicals (called muscarinergic cholinoceptors and alpha-adrenoceptors); stimulate the uptake of the vitamin choline in the hippocampus region of the brain; increase memory performance and learning capacity; improve equilibrium in cases in which it is disturbed; improve circulation, especially in fine vessels; improve the formation and flow of blood through the heart and blood vessels; act as a protective antioxidant; inhibit platelet aggregation, a primary cause of hardeing of the arteries; protect nerves. These various activities are due to the presence of terpene lactones, flavone glycosides, flavonoids, ginkgolides and bilobalide. 2,3,4,8,9

Contemporary Uses Approved by Authoritative Bodies

Germany’s Commission E supports the use of Ginkgo biloba extract for “symptomatic treatment of disturbed performance in organic brain syndrome within the regimen of a therapeutic concept in cases of demential syndromes with the following principal symptoms:”
• Memory deficits
• Disturbances in concentration
• Depressive emotional condition
• Dizziness
• Tinnitus
• Headache

Germany’s Commission E states more specifically that the primary uses of Ginkgo biloba extract are:
• Primary degenerative dementia (losing mental function as a result of aging)
• Vascular dementia (losing mental function due to impaired blood flow in the brain) and
• Mixed forms of both.

WHO supports the use of Ginkgo biloba extract for symptomatic treatment of mild to moderate cerebrovascular insufficiency (poor circulation in the brain), with the same symptoms listed by Germany’s Commission E, with the addition of:
• Headache
• Raynaud disease
• Acrocyanosis (bluish discoloration of the extremities)
• Post-phlebitis syndrome (painful swelling of veins)

It is important to understand that not all forms of impaired mental function are due to impaired circulation, and thus not all forms of impaired mental function will respond to treatment with Ginkgo biloba. Kreutzfeld-Jacob Disease, for example, produces a gross loss of mental function as the brain becomes filled with holes like Swiss cheese. This, and numerous other types of degenerative brain disorders will not respond to ginkgo treatment. Thus the nature of any reduction in mental capacity should be established. 2,3,4

Potential Risks

The following information is derived from the World Health Organization, Germany’s Commission E, and the AHPA Botanical Safety Handbook.

Safety issues and concerns
• Infrequent incidents of stomach or intestinal upsets or headaches. 3,4

Contraindications – based on conditions and medication intake, etc.
• There are no contraindications known for use of Ginkgo biloba during pregnancy.
• There are no contraindications known for use of Ginkgo biloba while nursing.
• Ginkgo biloba extracts show no mutagenic or carcinogenic activity.
• WHO and Commission E state that Ginkgo biloba is contraindicated in cases of hypersensitivity to Ginkgo biloba preparations. Neither one describes the nature of such potential hypersensitivity.

Potentially harmful drug interactions
• Ginkgo Biloba extract may increase the effect of blood thinning agents and aspirin. (Herbal Med, AHPA 57-58)
• Ginkgo biloba extract may beneficially increase the activity of papaverine, used in the treatment of male impotence.
10

Allergy precautions
• Infrequent incidents of allergic skin reaction. 4

Usage Tips

Unless otherwise directed by a physician, use 120 – 240 mg daily of Ginkgo biloba, in two or three doses daily. For memory deficits, disturbances in concentration, and depressive emotional condition due to impaired circulation in the brain, use:
• 60 mg 2 times per day, equals 120 mg. or,
• 40 mg 3 times per day, equals 120 mg.

For vertigo, tinnitus and headache due to impaired circulation in the brain, use:
• 120 mg 2 times per day, equals 240 mg. or,
• 80 mg 3 times per day, equals 240 mg.
2,3,4

Product Choosing/Buying Tips

Look for standardized extracts of Ginkgo biloba containing 24% flavone glycosides and 6% terpene lactones. Doses in these products will range from 40 – 80 milligrams per tablet/capsule.

Science Update

In the past years, hundreds of studies have been conducted on Ginkgo biloba, making it certainly one of the most exhaustively investigated botanicals of all time. The following few studies give some of the highlights of more recent ginkgo research.

In a human study of Ginkgo extract combined with a chemotherapy drug and administered to colon cancer patients, the combination proved more effective than the chemotherapy alone. This finding suggests that Ginkgo biloba extract may be an effective adjunct in chemtherapy treatment. 11

In a double-blind, placebo-controlled human clinical study, the effects of Ginkgo were compared with those of a group of Alzheimer’s drugs called cholinesterase inhibitors. At the end of the six month study, researchers found that results of the two were comparable. This study shows that at present, Ginkgo biloba extract proves as effective in the mitigation of Alzheimer’s as the cholinesterase inhibitor class of drugs. 12

In a human study on the effects of Ginkgo on blood sugar levels in normal individuals, ginkgo appeared to stimulate insulin production. Unexpectedly, ginkgo also lowered blood pressure among subjects. 13

Additionally;

In a study of Alzheimer’s patients given Ginkgo biloba extract, improvement was observed in the group of patients with very mild to mild cognitive impairment, while in more severe dementia, ginkgo functioned more to stabilize or slow down worsening of condition. 14

A study in the Annals of the New York Academy Of Sciences reported that administration of a Ginkgo biloba extract, protects against age-associated oxidative damage to mitochondrial DNA, oxidation of glutathione, and other signs of oxidative damage to mitochondria. The bottom line? Ginkgo biloba extracts protect cells and demonstrate anti-aging activity. 15

A study reported in Planta medica suggests that ginkgetin from Ginkgo biloba is associated with anti-inflammatory activity against skin inflammatory responses. 16

A study reported in Therapie reported that Ginkgo biloba extract protects the retina and the heart against damage due to constricted blood flow via its antioxidant properties and its regulation of oxygen use in the mitochondria of cells. 17

Controversies

Most of the “controversy” surrounding Ginkgo biloba is at this point in time generated by the media, which plays a constant game of see-saw between the pharmaceutical sector and the botanical sector. The body of science behind ginkgo is outstanding, as good as that for most pharmaceutical drugs, and better than that of many. But the economic implications of ginkgo’s increasing popularity are staggering. Drug companies cannot patent Ginkgo, and therefor stand to lose billions of dollars in sales that could go to other, proprietary drugs. For this reason, critics from the pharmaceutical sector are willing to attack ginkgo, and recommend prescription drugs instead. This type of controversy, or articles and news features pro and con, causes a great deal of confusion in the general public. The vast body of science on ginkgo biloba clearly points to a remarkable therapeutic aid which demonstrates benefits in cases of impaired function due to reduced circulation. But proven efficacy does not mean that Ginkgo biloba, and other botanicals, will not continue to be aggressively attacked from time to time in the media.

Trivia

• Ginkgo is so ancient it is considered a “living fossil.”
• Ginkgo is revered as a sacred tree, and is planted near temples in Japan and China.

References:

1. McGuffin M, Hobbs C, Upton R, Goldberg A (eds.). American Herbal Products Association’s Botanical Safety Handbook. 1st ed., (Boca Raton, FL: CRC Press. 1997): 57-58

2. World Health Organization. WHO Monographs on Selected Medicinal Plants, Vol. 1. (Geneva, Switzerland: World Health Organization. 1999): 154-167

3. Blumenthal M, Busse W, Goldberg A, Gruenwald J, Hall T, Riggins CW, Rister RS (eds.). The Complete German Commission E Monographs: Therapeutic Guide to Herbal Medicines. S. Klein, R.S. Rister (trans.). 1st ed., (Austin, TX: American Botanical Council. 1998): 136-138.

4. Blumenthal M, Goldberg A, Brinckmann J (eds). Herbal Medicine: Expanded Commission E Monographs. 1st ed., (Newton, MA: Integrative Medicine Communications. 2000): 160-169.

5. Foster, Steven Ginkgo 1st ed., (American Botanical Council, Austin, TX 1991)

6. Michel, P., Hosford, D. “Ginkgo biloba: from “living fossil” to modern therapeutic agent.” In P. Braquet (ed) Op cit 1988, 1-8.

7. Bown, Deni. The Herb Society Of America Encyclopedia of Herbs & Their Uses. (1st ed., (New York: Dorling Kindersley,1995): 288

8. Leung AY, Foster S. Encyclopedia of Common Natural Ingredients Used in Food, Drugs and Cosmetics, 2nd ed., (New York: John Wiley & Sons, Inc. 1996): 274-277

9. Bruneton J. Pharmacognosy, Phytochemistry, Medicinal Plants. 2nd ed., (Paris: Lavoisier Publishing 1993): 282-285.

10. Blumenthal, M., “Interactions between herbs and conventional Drugs” HerbalGram #49 2000. 60

11. Hauns, B., Haring, B., Kohler, S., et al. “Phase II study of combined 5-fluorouracil/Ginkgo biloba extract (GBE 761 ONC) therapy in 5-flourouracil pretreated patients with advanced colorectal cancer.” Phytotherapy Research. 2001, 15:34-38.

12. Wettstein, A., “Cholinesterase inhibitors and Ginkgo extracts- are they comparable in the treatment of dementia?” Phytomedicine. 1990/2000, 6:393-401

13. Kudolo, G., “The effect of 3-month ingestion of Ginkgo biloba extract on pancreatic B-cell function in response to glucose lading in normal glucose tolerant individuals.” J. Clin Pharmacol 2000, 40:647-654.

14. Le Bars, P., Velasco F., Ferguson J., Dessain E., Kieser M., Hoerr R. “Influence of the severity of cognitive impairment on the effect of the Gnkgo biloba extract Egb 761 in Alzheimer's disease.” Neuropsychobiology. 2002;45(1):19-26

15. Sastre J, Borras C, Garcia-Sala D, Lloret A, Pallardo FV, Vina J.“Mitochondrial Damage in Aging and Apoptosis.” Ann N Y Acad Sci. 2002 Apr;959:448-451. PMID: 11976217

16. Kwak, W., Han C., Son K., Chang H., Kang S., Park B., Kim H. “Effects of Ginkgetin from Ginkgo biloba Leaves on Cyclooxygenases and In Vivo Skin Inflammation.” Planta Med. 2002 Apr;68(4):316-321.

17. Clostre, F. “Protective effects of a Ginkgo biloba extract (EGb 761) on ischemia-reperfusion injury” Therapie. 2001 Sep-Oct;56(5):595-600.