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ginkgo biloba graphic

Ginkgo biloba

Ginkgo biloba is an extract from the leaves of the Ginkgo tree, also known as the Maidenhair tree. The Ginkgo is the oldest living tree species on earth and has been used medicinally by the Chinese for some 4,000 years.

Claimed health benefits

  • Increases blood flow to the brain, theoretically improving cognitive function.

  • Enhances memory, especially in people with age-associated memory impairment problems.

  • Alleviates calf muscle blood vessel athersclerosis, thus reducing pain when walking.

 

Evidence for health benefits

Ginkgo biloba's ability to increase blood flow to the brain has been demonstrated in many scientific studies. A 1994 analysis of 11 placebo-controlled, randomized double blind studies concluded that blood flow was increased in comparison to the placebo group. Six out of seven studies confirmed Ginkgos effectiveness while one study was inconclusive[1]. The possibility of this increased blood flow increasing cognitive ability or intellect is yet to be proven among healthy humans. Ginkgo biloba extract has been shown to be capable of stabilizing and, in a substantial number of cases, improving the cognitive performance and the social functioning of demented patients [2].

The ability of Ginkgo biloba to enhance blood flow has also been shown to alleviate other disorders such as calf muscle blood vessel athersclerosis and varicose veins. A placebo-controlled, double-blind study of the effectiveness of Ginkgo biloba special extract EGb 761 in 60 people found that those taking the extract increased their walking distance which was previously limited by blood flow problems in the lower extremities [3].

 

Cautions

Side effects from taking Ginkgo biloba are few and mild with the most severe reports being gastrointestinal problems, headaches and allergic skin reactions [4]. Very large doses may cause restlessness, diarrhea, nausea and vomiting [5].

It is important to remember that dietary supplements do not have to be manufactured to any standards, and thus supplements from different manufacturers are likely to vary in quality. [tell me more]

There is a distinct lack of scientific data on the safety of herbal supplements when taken by children and pregnant or breast feeding women. If you fit into these categories do not take herbal supplements.

As with all dietary supplements, make sure that you inform your physician of what you are taking when you visit.

 

Dose

The daily dose of Ginkgo biloba that has been used in research is between 120 and 160mg [6].

 

Choosing the brand

Ingredients

The actual active ingredients in Ginkgo biloba are bioflavonoids and ginkgolides. These are usually called Ginkgo biloba extract or GBE. When purchasing a supplement look for any of these substances.

Contamination

The people who harvest herbs for these products are not qualified botanists and there have been many reports of unwanted and sometimes poisonous parts of the plants or other plants being picked and added to herbal remedies. Some journals have speculated that liver damage of unknown origin might stem from herbs more often than doctors realize, and a representative for the Centers for Disease Control and Prevention even suggested that some herbal supplements may be contaminated with real drugs for extra "punch".

Cost per month

$75.00 (based on prices in a mid-western city, March, 2000)

 

References

1. Hopfenmuller W: Evidence for a therapeutic effect of Ginkgo biloba special extract. Meta-analysis of 11 clinical studies in-patients with cerebrovascular insufficiency in old age. Arzneimittelforschung 44(9):1005-13, 1994.

2. Le Bars PL, Katz MM, Berman N, Itil TM, Freedman AM, Schatzberg AF: A placebo-controlled, double-blind, randomized trial of an extract of Ginkgo biloba for dementia. JAMA Oct. 22-29;278(16):1327-32, 1997.

3. Blume J, Kieser M, Holscher U: Placebo-controlled double-blind study of the effectiveness of Ginkgo biloba special extract EGb 761 in trained patients with intermittent claudication. Vasa 25(3):265-74, 1996.

4. Tyler VE: What Pharmacists Should Know About Herbal Remedies: Pharmacists can help patients differentiate between the useful herbs and the harmful ones. J Am Pharm Assoc NS36(1):29-37, 1996.

5. Foster S: Herbal Medicine: An Introduction for Pharmacists. NARD J 10:127-144, 1996.

6. Tyler VE, Foster S: Herbs and phytomedicinal products, in Handbook of Nonprescription Drugs, Ed 11. Washington, American Pharmaceutical Association, 1996, pp 695-713