A Closer Look at Ginkgo Biloba

Aug. 6, 2007
About a decade and a half ago, ginkgo was the hot new "brain-building" herb, touted as the natural way to pump up our memory and enhance our cognitive abilities.

There was even hope it could help to slow or prevent the onset of Alzheimer's disease. Then, it seems, our attention shifted to other "next big thing" in brain nutrition, omega-3 fatty acids (particularly DHA). Omega-3 fatty acids were already familiar to most consumers as healthy fats. But they had another huge advantage over gingko: They were naturally available in a variety of foods and food ingredients, such as fish, flax and nuts (especially walnuts).

As people were forgetting about ginkgo, new techniques of microencapsulation meant omega-3 s could be incorporated into virtually any food or beverage. By now, ginkgo seemed a little strange and definitely remote by comparison. But maybe we should refresh our memory about this old herb.

Ginkgo biloba has a folk history that goes back centuries. Known commonly as the "Maidenhair tree," Ginkgo was referred to as a living fossil -- its closest relatives are extinct -- by none other than Charles Darwin. The trees thrive naturally in two areas in China, the Zhejiang province in eastern China and in the Tian Mu Shan Reserve. Sporting 4-inch leaves that quickly turn yellow and drop when autumn appears, ginkgo trees grow from 60 to over 160 feet tall.

Deep roots and natural resistance to harsh weather, insects and disease allows some species to reach a ripe old age estimated to exceed 2,500 years. Today, ginkgo trees are cultivated in France, Japan and Korea. In the U.S., they're cultivated in South Carolina, but grow in numerous other states as well.

Claims, and (Over-the-) Counter Claims

As a part of traditional Chinese medicine, the ground ginkgo seeds and leaves have been used to treat asthma, bronchitis and heart dysfunction for more than 5,000 years. In 1965, Willmar Schwabe, Ph.D., introduced ginkgo to Germany where the standardized leaf extract (designated EGb 761) is marketed as Tebonin, Tanakan and Rokan. It is extensively prescribed in Europe for memory and concentration problems, confusion, depression, anxiety, dizziness, tinnitus (ringing in the ears) and even headaches.

Other claims for the herbal include preventing Alzheimer's disease, decreasing intermittent claudication (leg pain caused by narrowing of arteries), improving symptoms of sexual dysfunction, multiple sclerosis and other health conditions. In the US, it is primarily sold as a dietary supplement.

The active components of ginkgo include flavonoids, terpenoids and terpene lactones. Two of its flavonoids, ginkgolides and bilobalide, are exclusive to ginkgo. Animal studies suggest ginkgo may dilate blood vessels and reduce blood viscosity to increase blood supply. It also may modify neurotransmitter systems and diminish free radical damage. In this way, some believe ginkgo could protect neuronal and myocardial cells from ischemia.

Many clinical studies have been conducted to test ginkgo's therapeutic potential. Some have shown promising results for patients with Alzheimer's disease, intermittent claudication and tinnitus among others conditions. But results are not consistent. The National Institute on Aging conducted a trial on 200 healthy adults over age 60 and reported in 2002 that taking gingko for six-weeks did not improve memory.

In October, 2002, the Cochrane Collaboration, one of the world's most respected scientific reviewers of clinical medical trials, concluded the following after reviewing the research: "Ginkgo biloba appears to be safe in use with no excessive side effects compared with a placebo. Many of the early trials used unsatisfactory methods, were small and we cannot exclude publication bias. But overall there is promising evidence of improvement in cognition and function associated with ginkgo. Our view is that there is need for a large trial using modern methodology to provide robust estimates of the size and mechanism of the treatment effects."

However, many studies have since ensued, and April this year, in the most recent Cochrane Collaboration review, the authors concluded, following the same caveats on side effects and initial trials, "The evidence that Ginkgo has predictable and clinically significant benefit for people with dementia or cognitive impairment is inconsistent and unconvincing."

Presently, The National Counsel on Complementary and Alternative Medicine (NCCAM) is conducting a clinical trial of ginkgo with more than 3,000 volunteer subjects. The objective is to assess ginkgo's potential to prevent Alzheimer's disease, cognitive decline and functional disability. NCCAM is also conducting trials to gauge its effect on asthma, multiple sclerosis, vascular function and cardiovascular disease, as well as its potential interactions with prescription drugs.

Whether or not we long remember Ginkgo depends to a great degree on the results of these ongoing studies. Nevertheless, it still shows strong sales as a supplement and in teas and other beverages. Should any of these subsequent studies show positive outcome for the plant, ginkgo could be poised for a comeback that would merit significant attention from processors.

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