Order: Ginkgoales

Family: Ginkgoaceae

Common Names:Maidenhair tree : named for the resemblance of the leaves to those of the maidenhair fern

Ginkgo

Yajiao : duck foot (Japanese)

Introduction

Ginkgo biloba is one of the most unique trees on the planet today. It is so removed from other modern trees that it stands alone in its own Order. Charles Darwin called the tree a 'living fossil', and indeed fossils of ginkgo trunks and leaves have been found dating it back to the lower Jurassic age, more than 190 million years ago! (Jalalopour et al 1999)

The tree is deciduous, dropping its leaves in an autumn display of gold. It is dioecious in nature (separate male and female trees), and the fruit of the female tree is quite distinctive with a highly disagreeable odour associated with the fleshy outer coating (Dallimore and Jackson, 1966).

Traditionally, records show the ginkgo tree has been cultivated in China and Japan for around two thousand years. The actual origin of the tree is uncertain. It is very tolerant of a range of climates, but performs best with an average temperature of 10 - 18C, rainfall of 600 ­ 1000mm and a summer maximum and with little wind. (Hori et al 1997).

Traditional medicinal uses of Ginkgo

The ginkgo tree has been revered in eastern culture for thousands of years as a medicinal plant. Chinese and Japanese herbalists have long known of its properties and have cultivated ginkgo in and around temples and shrines, in the courtyard of villages and in schoolyards not only for spiritual values which the tree lends, but also to have a handy supply of the leaves and nuts.

Steeping dried leaves in a tea, or used as an extract distilled from the leaves, ginkgo was very important in Chinese and Japanese traditional medicine, and was used in the treatment of many illnesses (Hori et al 1997), including:

• Poor circulation and associated illnesses
• Deafness, tinnitus and vertigo ­ illnesses all associated with an inner ear imbalance
• Absent-mindedness, and dementia in older members of the community
• Hypertension and depression in the aged
• Impotence in men.

The leaves were collected at different times of the year, according to their intended use, with some collected in late summer when the green colour is at its most vibrant and others in mid autumn when the leaves reached a golden hue (Hobbs 1994).

Autumn colour of the ginkgo tree.

The nuts also played an important part in traditional medicine in Japan and China. After feasts they were often ground up into porridge and eaten to aid digestion. Children who repeatedly wet the bed were given roasted ginkgo nuts as a cure. Despite the medicinal properties of the nuts, in large doses they are quite poisonous, and care must to be taken in administering them (Hori et al 1997)

The recent popularity of ginkgo extracts in herbal and alternative treatments has prompted widespread scientific study of the plant. Medical studies of the leaf extract have aimed to prove the theories held by generations of Chinese herbalists, and to discover modern medicinal uses for the extract.

Biochemical studies have concentrated on the flavonoids that are contained within the ginkgo leaf, known as ginkgolides and bilobalides. (Biosynergy 1999, Janssens 1999). While not particularly originally named, these compounds make up the active ingredients within the plant extract, and much of the curative properties of the ginkgo tree are due to the activities of these flavonoids. The following is a collection of studies undertaken to prove the beneficial elements of ginkgo to modern science.

Poor circulation.

It has been widely held for thousands of years that an extract from the leaf of the Ginkgo biloba tree aided in the circulation of blood around the body. Recent studies have proved that this is true, and that the flavonoids contained in the leaf have anti-ischaemic effects in blood. Janssens (1999) showed that this was caused by bilobalide acting on the mitochondria in the blood, allowing it to continue its respiratory activities when the blood flow is altered, thus protecting the body against the onset of ischaemic-induced damage. The implications of this are that the bloodflow to areas of the body that are at risk of being damaged is increased. This was seen in another study by Janssens on the effect of ginkgo extract on the development of varicose veins (*Janssens 1999), which showed that the development of varicose veins by poor blood circulation was reduced with the use of ginkgo extract.

Blood circulation is increased to many other areas of the body with the use on ginkgo extract. A study into the effects of Ginkgo biloba extract showed that it increased movement of blood to the eyes which has the effect of reducing the onset of blindness and other ocular blood flow disorders (Chung 1999).
The positive effect which ginkgo has on the circulation of blood around the body has also been useful in the treatment of heart disease. Many studies have been conducted on this, and these have shown that there is Platelet Activating Factor (PAF) working in conjunction with the flavonoids, to break down arterial plaque. The consequences of this are more flexible arteries, and this coupled with increased blood flow decreases the chance of heart disease (Biosynergy 1999).

Tinnitus

The use of ginkgo leaf extracts for the treatment of tinnitus was popular among the Chinese herbalists, and recent scientific studies have been testimony to the positive effect of the herb on tinnitus. One such study by Jastreboff et al (in Life Extension Foundation, 1999) used rats to study the affect of ginkgo extract on tinnitus on rats. This study showed significant decrease in the behavioural manifestation of tinnitus.

Memory loss

Increased blood circulation (see Poor Circulation) also improves memory by creating a greater flow of oxygen to the brain. Two very recent experiments have shown this using mice with induced cerebral ischeamia. The mice showed a great improvement when given the ginkgo extract, with increased demonstrated memory in a maze (Gajewski et al 1999) and reduced effects in induced amnesia (Tadano et al 1998, p127). With enough ginkgo extract the unfortunate mice will be smart enough to escape any more scientific tests.
Ginkgolides and bilobalides also have strong antioxidant properties (Lugasi et al 1999). Antioxidants are vital in our body in the scavenging of free radicals, which break down existing human tissue and cells. The brain is very vulnerable to free radicals; however, antioxidants such as those contained in ginkgo extracts can minimise cumulative free radical damage.
Dementia is a severe form of memory loss, especially in the aged. Itil et al (1999) conducted a study comparing the effects of conventional drugs used to treat dementia in America with use of a common ginkgo extract. This study concluded that ginkgo was in fact more effective on more patients than the synthetic conventional drugs.

Hypertension, depression and impotence

As well as affecting normal tissue, Ginkgo biloba extract has the ability to affect the nervous system of the body. Trovero et al (1999) showed that receptors in the body were altered by ginkgo extract. Receptors control the physical symptoms of depression and hypertension, and thus ginkgo extract may be beneficial in the treatment of the diseases. More study is needed in this area.

The curative properties of ginkgo extend into the field of impotence. A common problem with many older men, impotence is related to both the blood flow to the penis, and with associated depression induced sexual dysfunction. The effects that ginkgo has on both of these conditions has already been discussed (see poor circulation.)

New Developments

Studies are continuing into the medical science of Ginkgo biloba and hence, new uses are being found for the leaf extract. One such example of this is the protective properties that the extract has on diabetic tissue. Studies show that enzyme activity is increased in diabetic tissue after the use of Ginkgo biloba extract, a protective effect for the affected tissue (Punkt et al 1999).

Side effects

Within all of the studies given in this page, there were only very minor side effects noted. Some headaches and a small percentage of mild gastrointestinal problems were reported. This seems to affect only a small percentage of patients.

The range of studies that have been undertaken for ginkgo extracts are limited, and there is still much that we do not understand about ginkgo. Many health companies are eager to boost the popularity of ginkgo extract as it is potentially very profitable, and as a result most of the reported studies show ginkgo extract in a positive light. While not discounting any of the studies mentioned in this report, there is a need for greater study into ginkgo extract.

Conclusion

With so many positive effects for humans, it is not surprising that ginkgo extracts are growing in popularity so rapidly. There are currently more than 24 different brands of ginkgo extract on the market in the US at the moment (Itil et al 1998). Most of these contain the extract Egb 761 that claims to contain ginkgolides and bilobalides. This page does not aim to endorse any particular company or product, and any enquires about ginkgo should be aimed at your local health care professional.

Ginkgo Link-go Pages

The Ginkgo Tree - One womans ode to Ginkgo biloba - http://spider.albion.edu/student/ssonnad

Introduction to the Ginkgoales - A comprehensive guide to everything ginkgo - really lovely images as well . http://www.ucmp.berkeley.edu/seedplants/ginkgoales/ginkgo.html

Biosynergy - a vitamin company with a lot of information about traditional uses for Ginkgo biloba as well as modern developments http://www.biosynergy.com/ginkgo.htm

Life Extension Foundation - a really good site with heaps of references on scientific studies on the medical advancements in medical studies on Ginkgo biloba http://lef.org/prod_hp/abstracts/php-ab280.html#7

REFERENCES:

Biosynergy, http://www.biosynergy.com/ginkgo.htm visited 28th August 1999, 11:30 am

Life Extension Foundation, http://lef.org/prod_hp/abstracts/php-ab280.html#7 visited 28th August 12noon

Chung HS, Harris A, Kristinsson JK, Ciulla TA, Kagemann C, Ritch R, 1999, Ginkgo biloba extract increases ocular blood flow velocity In: Journal of Ocular Pharmacology and Therapeutics 15 (3): 233 - 240

Dallimore W and Jackson AB 1966 A Handbook of Coniferales and Ginkgoaceae, 4th edition. Edward Arnold publishers Pp229 - 233

Gajewski A and Hensch SA, 1999, Ginkgo biloba and memory for a maze. In: Psychological Reports 84 (2): 481 - 484

Hobbs C, 1994, Ginkgo - The Elixir of Youth. Botanica Press, Capitola

Hori T, Ridge RW, Tulecke W, Del Tredici P, Tremouillaux-Guiller J, Tobe H, 1997 Ginkgo biloba - A Global Treasure Springer Publishing

Jalalpour J, Malkin M, Poon P, Rehrmann, E, Yu J, http://www.ucmp.berkeley.edu/seedplants/ginkgoales/ginkgo.html : visited 28th August 1999 11am

Janssens D, Remacle J, Drieu K, Michiels C, 1999, Protection of Mitochondrial Respiration Activity by Bilobalide In: Biochemical Pharmacology 58 (1): 109 - 119

*Janssens D, Michiels C, Guillaume G, Cuisinier B, Louagies Y, Remacle J, 1999, Increase in circulating endothelial cells in patients with primary chronic venous insufficiency: Protective Ginkor Fort in a randomised double blind, placebo controlled clinical trial. In: Journal of Cardiovascular Pharmacology 33 (1): 7- 11

Lugasi A, Horvahovich P, Dworschak E, 1999, Additional information to the in vitro antioxidant activity of Ginkgo biloba: In: Phytotherapy Research 13 (2): 160 - 162

Punkt K, Psinia I, Welt K, Barth W, Asmussen G, 1999, Effects on skeletal muscle fibres of diabetes and Ginkgo biloba extract treatment. In: Acta Histochemia 101 (1): 53 - 69

Tadano T, Nakagawasai O, Tanno K, Motikawa Y, Takahashi N, Kisara K, 1998, Effects of Ginkgo biloba extract on impairment of learning induced by cerebral ischemia in mice. In: American Journal of Chines Medicine. 26 (2): 127 - 132