Gingko
Overview
Some estimates state the ginkgo tree has been in existence for more than 200 million years, which would make it one of the oldest tree species in the world. A gingko tree can live for 1,000 years and grow to a height of 30 meters or 100 feet.
The leaves are fan shaped and attach to branches which are short and horizontal. The fruit of the gingko tree is inedible and smells foul, and it has a seed which resembles an almond. The trees are cultivated the world over to meet the medicinal demands for gingko, and are highly favored by landscapers because they can flourish in adverse conditions in urban environments.
The leaves of the gingko tree are the part which is used to make medicines in both Europe and in North America. Gingko products have been available for several decades without a prescription. In Traditional Chinese Medicine (TCM), the fruits are also used as supplements.
Gingko Health Benefits
Oddly, although this herb has been used in TCM for uses such as ‘benefitting the brain’ and as an astringent for the lungs and the relief of asthma symptoms, gingko is not thought of as a terribly important herb in TCM circles. In Europe, however, gingko is considered a conventional drug and annual sales there are estimated to be over $500 million US annually.
Many studies have proven that gingko has a positive effect on the cardiovascular system by increasing blood flow. A typical continued dose of gingko has been shown to decrease blood vessel elasticity, increase coronary blood flow, increase cerebral blood flow, decrease blood viscosity and decrease erythrocyte aggregation.
The compounds in the gingko extract which are responsible for these beneficial effects have not been identified but current thought points to the flavonoids and the ginkolides. The flavoinoids of the extract are also thought to possess highly effective antioxidants. The antioxidant activity which gingko exhibits is believed to play a large role in several of this herb’s therapeutic actions, particularly its neuroprotective effect and ability to protect from ischemia-reperfusion damage.
Gingko is used extensively in the treatment of ‘chronic cerebral insufficiency.’ This activity can include memory loss, confusion, fatigue, difficulty concentrating, anxiety, dizziness, tinnitus, headache, depressed mood and decreased physical strength. Most physicians believe this is due to an impairment of the cerebral circulation, which is improved by daily consumption of gingko. Taking 40 mg of gingko extract three times daily for one year showed significant improvements in short-term memory, mood disturbances, alertness, vertigo, headaches and tinnitus. More recent tests showed the same results, with those taking daily doses of gingko scoring significantly higher on several different cognitive function tests.
One study of patients suffering from arthritis showed that those treated with gingko for 6 months had significantly greater relief from pain and exhibited better tolerance to walking than those who took placebos. The benefits continued during the remainder of the 65-week trial period.
When gingko is used to treat patients with ischemic heart disease, it is also believed the positive effects are due to its antioxidant properties. Studies have shown that gingko improved cardiac mechanical recovery, diminished the decrease of myocardial ascorbate during reperfusion and suppressed the leakage of lactate dehydrogenase.
Other studies show that extracts of gingko can have a positive influence on neuron metabolism and neurotransmitter disturbances. It has also been suggested that the bilobalides in gingko may help in the regrowth of damaged neurons in the central nervous system.
In recent years, there has been much attention placed on using gingko biloba extract as part of a management plan for dementia. Various studies and tests suggest that gingko may indeed be useful in the successful treatment of vascular dementia or dementia which is related to the onset of Alzheimer’s disease.
Another study of patients using gingko extract for the treatment of several various disorders due to aging for a period of more than three months showed significantly higher scores on specially-designed geriatric clinical evaluation tests. The benefits continued to increase in subsequent months.
Other studies in which gingko was used to treat patients with resistant depression had good results, with the gingko showing significantly better results than those using placebos or tetracyclic antidepressants. Studies with animals have also shown that gingko extracts may help to reduce the emotional and behavioral consequences of stress.
Studies have also been conducted in which gingko was used to treat patients with sudden hearing loss. Another study suggested that gingkolide B has a protective effect when used against neuronal damage following trauma. A study with rats suggested gingko biloba extract reduced brain swelling in response to injury and resulted in less impairment after the injury.
Dosage
Most of the research which has been conducted on the effects of gingko used a standardized extract of ginkgo-flavone glycosides at 24% and terpenoids at 6%. Recent studies show no significant differences between the various forms of dispensing gingko (drops, tablets and capsules). Standard recommendations are to consume 40 mg of the extract three times daily, or 300 mg of dried leaves per day.
Typical treatment for conditions which warrant the use of gingko suggest daily consumption for 1 to 3 months before positive results will be seen.
Adverse Effects
Most health care practitioners agree that there are no known drug interactions. However, there are some studies which suggest gingko may potentiate the actions of anti-coagulants.
Infrequently, gingko may be the cause of gastrointestinal disturbances and headaches.
Also, pregnant or nursing mothers should not use gingko as its safety for this group has not been sufficiently studied.
References
- Bone, K. A Clinical Guide to Blending Liquid Herbs: Herbal Formulations for the Individual Patient, Churchill Livingstone (2003)
- Braun, L. & Cohen, M. Herbs & Natural Supplements: An evidence-based guide, Elsevier (2005)
- Duke, J. The Green Pharmacy: Herbal remedies for common diseases and conditions from the world's foremost authority on healing herbs, Rodale Limited (2003)
- Kowalchik, C. & Hylton, W. Rodale's Illustrated Encyclopedia of Herbs, Schwartz Books (1987)
Posted in Ginkgo
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