Gingko Biloba
There has been a great deal of news about Gingko biloba and its supposed health benefits in treating everything from diminished memory to premenstrual syndrome.
The name Ginkgo derives from an incorrect transcription of the Japanese yin-kwo,
meaning silver fruit. Ginkgo biloba, or maidenhair tree, is native to China, Japan and Korea where, with its fan-shaped leaves, it is admired in temples and gardens. It has been used in Traditional Chinese Medicine since the 14th century for the treatment of asthma, cough, bladder inflammation, abnormal discharge and alcohol abuse.
Ginkgo biloba was introduced into Europe around 1730 and is now widely used as a medicinal plant in France, Germany and the United States. It was first mentioned in European medical texts for digestion. Recently, the leaves of Ginkgo biloba have been used in Europe for circulatory disorders. In 1997, Ginkgo biloba was the best-selling herb in Europe, while in the United States sales reached $66 million, up 140 per cent from 1992.
What can Ginkgo biloba do?
There has recently been a great deal of news about Ginkgo biloba and its supposed health benefits in treating everything from diminished memory to premenstrual syndrome (PMS). It has been approved by the German Commission E Monographs for treating the symptoms of dementia, disturbances in concentration, depression, dizziness, tinnitus (ringing in the ears from causes other than damage to the eardrum), vertigo, headache, Raynauds disease and calf pain and limping caused by lack of blood to the muscles.
Clinical studies show that daily doses of 120 to 240mg of Ginkgo biloba extract can improve blood flow, memory performance and learning capacity within eight to 12 weeks. Other research has shown that Ginkgo bilobas effect on the central nervous system is comparable to that of tacrine and other cognitive activators such as pramiracetam and vinpocetine as well as some anti-dementia medications.
Researchers studying the use of Ginkgo biloba for memory enhancement in geriatric patients found that one patient reported improvement in erections. Further studies into the use of Ginkgo biloba for erectile dysfunction have also noted marked improvement in erections. Interestingly, one study reported a greater sexual response from women than from men when patients were given 209mg of Ginkgo biloba per day as an antidepressant.
A French study of 165 women found Ginkgo biloba extract was effective in treating PMS, particularly breast symptoms. Another study (Quaranta et al, 2003) found that taking 40mg of Ginkgo biloba extract on a long-term basis improved visual field damage in patients who had normal-tension glaucoma (NTG). NTG is a condition where the optic nerve is damaged, and the authors of this study suggest that improved blood flow to the optic nerve may have accounted for the improvement in vision.
In elderly depressed individuals who werent responding to antidepressant drugs, researchers found Ginkgo biloba relieved symptoms of depression after four weeks of treatment.
Traditional Chinese Medicine uses the nuts from the Ginkgo biloba plant (called bai guo in Chinese) as opposed to using the leaves like Europeans do for wheezing, urinary
infections, incontinence and premature ejaculation. The theory behind how bai guo is prescribed also differs from Western thinking. Traditional Chinese Medicine commonly prescribes dried herbs in a formula which is boiled into a tea. They rarely prescribe herbs individually, as they believe the healing effect of a herb increases when it is combined with other herbs. Taking herbal medicines in a formula is also thought to override the toxicity of the individual ingredients. Ginkgo biloba nuts have been found to have a slightly more toxic effect than the leaves and should therefore only be taken when prescribed by a qualified Chinese Medicine practitioner.
How does Ginkgo biloba work?
Ginkgo biloba extract is thought to relax blood vessels and increase their tone, thus improving blood circulation. It also contains flavonoids which may enhance the neurotransmitters in the brain and explain why Ginkgo biloba improves brain function. The way Ginkgo biloba boosts the amount of glucose available to the brain may also explain how it improves brain function, as eating sugar will give you the same result, only the effect will be short-lived.
Another way Ginkgo biloba may help memory is through its antioxidant function. The brain and central nervous system are susceptible to free radical attack because of the high content of fatty acids in cells. Free radical damage is now recognised as playing an important role in many disorders associated with ageing, including Alzheimers disease, a progressive degeneration of brain tissue where, eventually, blood flow to the brain slows, depriving the cells of oxygen and glucose. Antioxidants help to minimise free radical damage. Furthermore, the effect of Ginkgo biloba on serotonin receptors in the brain makes it potentially useful in treating depression.
Side effects
No health risks have been found when the proper dosages of Ginkgo biloba extract are used. However, mild gastrointestinal complaints can occur and there have been some reports of blood pressure problems, headaches, allergic reactions and inflamed veins. Overall, Ginkgo biloba is very safe when consumed in normal quantities. As a precaution, children under the age of 12 are advised not to use Ginkgo biloba, as studies have only been conducted on people with dementia syndromes.
Dosage
Unless your doctor prescribes otherwise, 120 to 240mg of dry extract in liquid, tablet or capsule form should be divided into two or three doses to be taken daily. You will find that different brands of Ginkgo biloba products have different concentrations, so make sure you read the labels. Its also important to bear in mind that taking Ginkgo biloba for less than six to eight weeks has no effect but you should generally not exceed three months.
Although Ginkgo biloba is the worlds most ancient tree, its therapeutic value has only recently been realised in Western countries such as Australia. With our population rapidly ageing, we may find its potential for treating Alzheimers disease increasingly useful.
Remember, there can be contraindications with herbal medicines and pharmaceuticals alike. If you are already taking medication, consult your doctor before you start taking any herbal or nutrient supplements.
References available on request.
Kizzy Gandy, BHSc (Chinese herbal medicine), works in
regulatory affairs consultancy for complementary medicines and also runs a Chinese Medicine clinic in Dee Why on Sydneys Northern Beaches. She is currently completing a Master of Herbal Medicine at the University of Sydney.
Did you know?
Gingko biloba:
- is the oldest living tree species in the world
- is recommended for people suffering signs of dementia and symptoms such as disorientation,
memory loss, headache, depression, vertigo and tinnitus - has been shown to slow the progress of Alzheimers disease and to directly enhance cognitive function in the elderly
- protects nerve cells in the body and is a strong
antioxidant - increases the circulation of blood to the brain and other parts of the body and improves the supply of oxygen and uptake of glucose
- may interact with prescription drugs such as warfarin; and
- more than 400 studies have been conducted on Ginkgo biloba.
Source: Complementary Healthcare Council of Australia
