When I think of an herbal remedy that is a perfect example of the marriage of folklore and modern science, ginkgo biloba invariably comes to mind. No other herb better typifies the vast potential of plant medicines within the standards of modern medicine. Ginkgo is prescribed daily by thousands of doctors around the world, used by millions of people, and is one of the most frequently prescribed medications in both France and Germany. It also continues to be one of the most widely studied herbs, with new applications being discovered constantly.

Ginkgo's Background

Ginkgo biloba is the world's oldest living tree species, the sole survivor of the Ginkgoaceae tree family whose fossil record dates back more than 200 million years. Once widespread in North America and Europe, ginkgo was destroyed in many regions during the Ice Age, surviving only in China, where it was later cultivated as a sacred tree. Today ginkgo is planted widely throughout the United States, both for its ornamental value and because of its ability to resist insects and pollution.

The earliest mention of ginkgo biloba as a medicine is found in the Chinese materia medica, Pen T'sao Ching (The Classic of Herbs), published in 2800 B.C. and attributed to the emperor and sage Shen Nung. Mention is made of ginkgo's use for respiratory ailments (such as asthma), as well as its benefits for brain function. Indeed, when applying the ancient "doctrine of signatures", the ginkgo leaf bears an uncanny resemblance to the cerebral hemispheres.

Modern research on ginkgo dates back to the late 1950s when Dr. Willmar Schwabe of Schwabe Gmbh in West Germany found himself faced with the unenviable task of determining an optimal balance of the various components of the ginkgo leaf for an extract that would give ginkgo's maximum medicinal benefits. The result of Dr. Schwabe's work was a standardized concentrated extract of ginkgo biloba leaves (24 percent flavone glycosides) known in Europe as EGB761 (marketed under the names Rokan, Tanakan, and Tebonin). The 27-step extraction process requires fifty pounds of dried leaves to yield one pound of the standardized extract and takes up to two weeks to complete.

Ginkgo's Active Compounds

Ginkgo biloba is a classic case of the sum of its components-100 or more-being greater than the action of any one component alone. This synergism was a critical consideration in the creation of the standardized extract. The more than 280 laboratory and clinical studies on the extract have firmly established the need for a guaranteed balance of these components to ensure optimal medical benefits from ginkgo.

The compounds most responsible for ginkgo's effectiveness are the flavone glycosides, sugars derived from the chemical of the natural color of the leaf (flavo- is a prefix indicating yellow; ginkgo leaves turn yellow-gold in the Fall), including kaemp-ferol, quercetin, isorhamnetin, and also proanthocyanidins. These compounds contribute to ginkgo biloba's powerful antioxidant and free radical scavenging properties.

Much recent research focuses on a set of alcohol-soluble terpenes, the most important of which are known as ginkgolides and bilobalides. These compounds, unique to ginkgo, show positive benefits in improving circulation, decreasing blood viscosity, and decreasing tissue damage during inflammation.

Ginkgo and Circulation

Ginkgo's meteoric rise in popularity over the last 15 years has been due, in part, to its documented ability to increase circulation to the brain and to the extremities. Numerous studies have shown that ginkgo protects arteries, veins, and capillaries from damage and also regulates their tone and elasticity. Additionally, ginkgo directly influences circulation by reducing the stickiness of platelets (a key factor in the formation of atherosclerosis) and by protecting red blood cells from destruction and keeping them evenly dispersed.

This means a healthier and more efficient delivery of oxygen to tissues of the body. Nowhere is this improvement more critical than in the brain. Studies have indicated that by age 70, blood flow to the brain is reduced by 20 percent. Individuals showing signs of dementia (including Alzheimer's disease) may have a reduction of over 30 percent. Proper circulation to the brain ensures sufficient delivery not only of oxygen, but also of glucose, the brain's primary fuel. It follows that optimal brain function depends on a large and constant supply of glucose and oxygen. Without these important circulation-dependent substances, a long list of conditions, including memory loss, decreased concentration, dizziness, vertigo, and tinnitus, can result.

Reduction in peripheral blood flow is another condition brought on by aging. The elderly often suffer from decreased blood flow to the legs, arms, and hands. This may manifest itself as Raynaud's Syndrome, intermittent claudication (muscular pain due to inadequate blood supply), numbness and tingling.

With its proven circulation-increasing capability, ginkgo is a logical choice for conditions associated with poor circulation, and numerous studies have indicated clinical benefits of ginkgo in circulatory disorders previously thought to be irreversible.

Ginkgo and Free Radicals

Ginkgo is one of the herbs with documented antioxidant properties. Studies in France have shown ginkgo to be very effective in protecting the lipid (fat) portion of cellular membranes from free radical damage. If one considers that the brain cells contain the highest content of unsaturated fats (lipids) of any cells in the body, this protective action further supports ginkgo's benefits for the central nervous system. Free radical damage in the rain and nervous system is widely postulated to be a major cause of accelerated aging.

Ginkgo can play a triple role in the protection of the cells of the body and particularly those of the brain. First, it increases circulation and the subsequent delivery of glucose and oxygen to cells. Second, in the presence of free radicals threatening cellular damage, ginkgo can protect cells from damage and scavenge free radicals from the system.

Ginkgolides and Platelets

Over the last five years, research on the ginkgolides has led to a medical breakthrough. Three ginkgolides (A, B, and C) have demonstrated the ability to inhibit a mediator in the body known as platelet-activating factor (PAF). PAF contributes to inflammatory conditions, shock, bronchial constriction, and gastrointestinal ulceration. PAF has also been implicated in asthma, organ transplant rejection, heart arrhythmias secondary to myocardial infraction, and vasculitis (inflammation of blood vessels). Research is underway in Europe and the United States to further investigate the ginkgolides' ability to inhibit the potentially damaging action of PAF.

Safety of Long-Term Ginkgo Use

Thanks to extensive research on both humans and animals, as well as to clinical trials, the safety of long-term use of ginkgo is well understood. There have been no reports of significant adverse reactions when ginkgo is used at the recommended dosage. Scattered reports of mild gastric upset and headache (short duration) have occurred in rare cases (less than 0.5 percent in one 1989 study). The less purified extracts that do not meet the standards set by Dr. Schwabe are more likely to cause these side effects. It should also be noted that elderly persons with a history of atherosclerosis and compromised blood flow to the brain should begin with a lower dose Of the ginkgo extract and build up to the recommended dosage over a period of two to three weeks. (Editor's Note: This advice is not intended to replace the recommendations of your health care practitioner.)

Dr. Brown, a member of [Let's Live's] Herb Advisory Board, is a naturopathic physician residing and practicing in Seattle, Washington. He is a faculty member of Bastyr College in Seattle. Dr. Brown is the founder and director of Natural Product Research Consultants (NPRC)

Reprinted with Permission from Let's Live magazine, April 1992.