(Austin, TX. December 9, 2002). Popular dietary supplements made of standardized concentrated extract of ginkgo leaf show promise in helping to improve memory associated with dementia in older patients, according to a major scientific review of 33 clinical trials.
Researchers at the Cochrane Collaboration at Oxford University in England reviewed and evaluated human clinical trials on standardized concentrated extracts of ginkgo leaf. The researchers focused on 33 clinical studies that it considered of acceptable design, size and quality and concluded that the herbal extract "appears to be safe in use with no excessive side effects." The trials lasted from 3 to 52 weeks, with most being 12 weeks.
According to a statement released by the Cochrane group, overall, "there is promising evidence of improvement in cognition and function associated with Ginkgo."
The statement also noted that many of the earlier trials on ginkgo were relatively small studies, had some design flaws, and/or used unsatisfactory testing methods. Also, the question of publication bias could not be excluded. Funding for the scientific evaluation was provided by the Alzheimer's Society of England in cooperation with Oxford University.
"Ginkgo standardized extract is approved as a medicine in several European countries for a variety of health conditions, primarily to treat memory loss and dementia associated with aging," said Mark Blumenthal, founder and executive director of the nonprofit American Botanical Council.
The psychological and physiological benefits of ginkgo are based on its primary action of regulating brain chemicals called neurotransmitters and exerting neuroprotective effects in the brain -- protecting against or retarding nerve cell degeneration. Ginkgo also benefits vascular microcirculation by improving blood flow in small vessels. It also has antioxidant activity.
"There has been much public confusion about the true benefits of ginkgo," Mark Blumenthal. Media reports about a ginkgo clinical trial  published in August in the Journal of the American Medical Association (JAMA) sent consumers a confusing message. The trial concluded that a leading ginkgo supplement did not produce measurable benefits for memory in healthy adults over 60. However, a month earlier, another study  concluded that the same ginkgo extract is effective in helping normal healthy older adults in memory and concentration.
"Unfortunately, the public's impression from the news generated by the JAMA was uncertainty about ginkgo's scientifically documented benefits," said Blumenthal. "Now, the Cochrane Collaboration, the world's most respected scientific reviewer of clinical trials in medicine, has concluded that the published literature strongly supports the safety and potential benefits of ginkgo in treating memory loss and cognitive disorders associated with age-related dementia."
All but three of the 33 studies reviewed by the Cochrane group were conducted on two ginkgo products made in Germany. The leading extract, on which 21 studies were conducted, is known as EGb 761® and is made by the W. Schwabe Pharmaceutical company of Karlsruhe, Germany. This extract is imported into the U.S. under the name Ginkoba® by Pharmaton Natural Health Products in Ridgefield, CT and Ginkgold® by Nature's Way of Spingville, UT. The other product on which 8 trials were conducted is known as LI 1370 and is made by Lichtwer Pharma of Berlin, imported and marketed as Ginkai® by Abkit Inc. in New York City.
Ginkgo preparations are made from the leaf of the ginkgo tree (Latin name Ginkgo biloba), the world's oldest living tree, dating back 250 million years. Ginkgo trees were found growing in China and northern Japan, and are now commercially cultivated in the U.S. and other countries. Extracts from ginkgo leaves are pharmaceutically concentrated and standardized to some of ginkgo's unique biologically active chemical compounds. The leading most well-researched ginkgo extract from Germany is licensed as a medicine in many countries worldwide. Ginkgo has been the top-selling herbal dietary supplement in the U.S. for the past five years, with sales of ginkgo dietary supplements in the U.S. in 2000 being measured over $99 million in the mainstream retail market , according to ABC's peer-reviewed journal, HerbalGram. Total ginkgo sales in 2001 for all channels of trade were estimated at $180 million by Nutrition Business Journal.
About the American Botanical Council
The American Botanical Council is the nation's leading nonprofit organization addressing research and educational issues regarding herbs and medicinal plants. The 14-year-old organization occupies a 2.5 acre campus in Austin, Texas where it publishes HerbalGram, a peer-reviewed journal on herbal medicine, and will publish in 2003 a book and continuing education course for healthcare professionals, The ABC Clinical Guide to Herbs, containing an extensive science-based monograph on the safety and efficacy of ginkgo. Information contact: ABC at P.O. Box 144345, Austin, TX 78714-4345, ph: 512-926-4900, fax: 512-926-2345. Website: www.herbalgram.org.
1. Birks J, Grimley Evans J, Van Dongen M. Ginkgo Biloba for Cognitive Impairment and Dementia (Cochrane Review). In: The Cochrane Library, Issue 4, 2002. Oxford: Update Software.
2. Alzheimer's Society (UK) Press Release. October 21, 2002 Alzheimer's Dementia Care and Research.
3. Solomon PR, Adams F, Silver A, Zimmer J, DeVeaux R. Ginkgo for memory enhancement: A randomized controlled trial. JAMA 2002;288(7):835-40.
4. Mix JA, Crews WD. A double-blind, placebo-controlled, randomized trial of Ginkgo biloba extract EGb 761 in a sample of cognitively intact older adults: neuropsychological findings. Human Psychopharmacol Clin Exp 2002;17:267-77.
5. Blumenthal M. Herb sales down 15 percent in mainstream market. HerbalGram 2001;51:68. Market data includes food, drug and mass market retail stores, but does not include warehouse buying clubs (e.g., Costco, Sam's), convenience stores, natural food stores, multi-level and direct sales companies, mail order or Internet sales, or sales through health professionals.