Does China’s oldest tree contain memory magic?
The Irish Times
Health Supplement, p. 13
18 March 2008
DOES IT WORK? GINKGO HAS been one of the best-selling herbal remedies in many countries for a number of years. It is approved to treat Alzheimer’s disease in Germany, Belgium and the Czech Republic, as well as for memory problems in other countries. In Ireland, it is available only by prescription.
The remedy is made from the leaves of the ginkgo biloba tree, which is native to southeast Asia. The tree itself is believed to be the oldest living tree species, and has been called a “living fossil”.
It was so highly revered in China that it was planted around temples. The tree is extremely hardy, and was reported to have been one of the first forms of life to re-emerge after the atomic bombs were dropped in Japan.
Traditional Chinese medicine used ginkgo seeds for many different ailments, but recent interest has focused on extracts made from the distinctive fan-shape leaves. During the 1960s, German researchers were looking for herbs that would promote blood circulation. They made a standardised extract of ginkgo which they codenamed EGb 761. That extract continues to be the one most commonly researched and used, though now primarily for memory problems, especially in the elderly.
Evidence from studies
Much of the recent interest in ginkgo arose after a study was published in 1997 in the Journal of the American Medical Association. This study found that patients with Alzheimer’s disease or other illnesses leading to memory problems had less deterioration when taking ginkgo than a placebo.
Several studies before this found beneficial results, but many were not designed well or had very few participants.
Several studies have been carried out since, but did not get the same positive results. A systematic review of all this research concluded last year that results to date were so inconsistent that firm guidelines for using ginkgo could not be given.
The most recent study, published at the end of last month, examined healthy adults (over 85 years old) taking ginkgo for up to three and a half years. It found that ginkgo did not delay the development of memory problems any better than placebo.
Finding safe and effective ways to prevent dementia and memory loss remains a high priority. Ginkgo is being tested in the two largest dementia prevention trials ever to be conducted, with both planning to enrol around 3,000 participants each.
The results of these trials will give much-needed information to help guide future decisions about ginkgo.
Since ginkgo became popular, concerns have been raised about its use along with “blood-thinning” drugs (such as warfarin or aspirin). This concern arose in part because of how ginkgo was originally found. Several cases have been published suggesting a link between excessive bleeding and taking ginkgo.
However, an in-depth review published recently found little evidence to support these concerns. In controlled studies, participants did not report bleeding problems. Where cases of bleeding occurred, people had used brands with higher doses of active ingredients than are in EGb 761. This highlights the importance of finding well-made products. However, reviews of herbal remedies available in US shops and websites have consistently found that about half the products do not contain the recommended levels of active ingredients. Great care is needed in selecting any herbal remedy.
Most research has been conducted using the German brand, codenamed EGb 761. The usual dose recommended is 120 to 200 mg daily, divided into two or three doses. However, more research is needed to confirm the value of ginkgo and whether or when it should be prescribed.
Since ginkgo is only available in Ireland by prescription, you should talk to a doctor before talking it.
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