Ginkgo biloba is the oldest living tree species. The Chinese have been using it medicinally for millennia. In recent years, the use of ginkgo (sometimes misspelled gingko) biloba has experienced growing popularity.
The herb itself is from the gingko tree, which is one of the oldest trees still in existence today, going back 280 million years. This has been used a millennium in Chinese medicine and for centuries in Europe, particularly Germany. It has recently been approved in that country for the treatment of dementia.
This ornamental tree, native to the orient, is now cultivated around the world for its beauty, disease and pollution resistance, as well as for its medicinal value. The two major constituents are the flavonoids (called flavoglycosides or sometimes Ginkgo Heterosides), and the terpene lactones. All of the reliable studies have been performed with a 50:1 extract of the leaves, which have been further standardized to contain 24% flavoglycosides (flavone glycosides) and 6% terpene lactones. The various flavonoids are responsible for the tremendous anti-oxidant and free-radical scavenging activities associated with Ginkgo biloba extracts (GBE).
A 2002 examination of US marketed ginkgo products found that some products failed to meet the standards that were claimed on the bottle and therefore caution is advised in product selection. Ginkgo products are sold over-the-counter throughout the world and by prescription in Germany and France.
The ginkgolide class of chemicals has not been found in any other living species to date. The overall physiologic results of ginkgo use are increased perfusion to the brain and peripheral circulation, enhanced free radical scavenging, improved cerebral tolerance to hypoxia, and strengthened microvasculature.
Ginkgo biloba has been double-blind tested many times for its ability to increase the oxygen content to the brain and other bodily tissues. It has been shown to promote mental clarity and concentration, increase alertness and short-term memory and has been used preventatively in regenerative compounds for loss of memory and senility, in cardiac protection formulas against stroke and atherosclerosis and for hearing disorders and vertigo (dizziness) where blood flow is poor in the ears. It also offers significant protective action against the development of Alzheimer's disease, hearing loss and strokes, and it protects arterial walls.
The most studied active ingredient is Ginkgolide-B one of the terpene lactone constituents. Ginkgolide-B is a known inhibitor of Platelet Activating Factor (PAF), which is responsible for platelet aggregation, PAF-induced asthma and various inflammatory and pro-oxidative processes. By blocking PAF, GBE has an effect on the overall peripheral circulation, which is especially noticed in increased cerebral circulation. This increased brain circulation, when combined with PAF's ability to "recharge" nerve cells (via increased Na+-K+ ATPase activity) and the flavonoids blocking the lipid peroxidation along the nerve myelin sheath, have given GBE a well-deserved focus in brain function research.
Ginkgo extracts are used for almost any type of vascular disorder associated with spasms, hypoxia and free radical damage. Ginkgo is a mild antioxidant and may be useful in asthma, coughs, and allergies.
Ginkgo has been used successfully against Raynaud's disease, varicose conditions, dementia syndromes, vertigo and tinnitus of vascular origin, peripheral arterial occlusion, platelet aggregation and intermittent claudication. Ginkgo is also being investigated for its use immediately after stroke, in asthma, in sexual dysfunction, and in depressive disorders.
According to the Journal of American Medical Association, October 22/29, 1997, Volume 278, November 16, a double blind study was performed at Albert Einstein College of Medicine in New York, which revealed that Ginkgo Biloba was safe and capable of stabilizing as well as improving the thinking and social functioning of patients with "mild memory loss". Even in people who do not have a dementing disease, it seems to increase the memory and actually improve the IQ. It may take several months for the herb to show an effect and most of the time the effect is a subtle improvement.
Positive clinical effects have been seen with short-term memory, tinnitus (ringing in the ear), vertigo, concentration, slowing the onset of Alzheimer symptoms, intermittent claudication, impotence, migraines, allergies and asthma. Most of these studies were performed using 120-mg daily of the 24%-6% standardized extract. GBE has been reported in at least 10 different scientific articles, protecting eyes from the damage leading to macular degeneration, a leading cause of blindness. Many of these studies have been compiled into several volumes that are available through the American Botanical Council. The German Commission E has "Approved" the standardized extract of ginkgo leaves for brain functions (memory etc), intermittent claudication, and vertigo/tinnitus; although leaf extract preparations are "Unapproved" for the same.
The typical daily dose of ginkgo biloba for dementia syndromes is 120 to 240mg of a standardized extract. The higher doses are generally required for cerebral disorders. A suggested titration for Alzheimer's dementia would be 60mg bid for 6 weeks, then increasing the total daily dose by 40 to 60mg every 8 weeks if improvements are not visible.
The daily dose for intermittent claudication, Raynaud's disease, varicose conditions, and all other previously mentioned disorders is 120 to 180mg. The daily dose should be 60mg bid or tid, because flavones and terpenes have a short half-life. Patients should allow at least 6 to 8 weeks of therapy before maximal benefits are observed.
The active flavonoid compound is flavoglycoside. It is supplied in encapsulated extracts that should be standardized to 24% of the flavoglycoside. The capsules come in 40 to 60mg size and four to six a day are recommended for improving mental function.
Adverse effects related to ginkgo are relatively mild and infrequent and include nausea, headache, diarrhea, dizziness and occasional allergic dermatologic reactions. However, rare cases of hematomas and bleeding have been reported. Ginkgo biloba does not interact with any drug, so it can be taken regularly.
Ginkgo's antiplatelet effect should be considered if the patient is taking other agents with similar blood-thinning actions. Tell your physician if you are taking Ginkgo, and do not vary the dose without telling him.
Patients with mild to moderate Alzheimer's-type dementia have shown statistically significant improvement with Ginkgo use. One effect of Ginkgo extract is that of promoting vasodilation and blood flow, thus providing a therapeutic effect on cognitive disorders and high blood pressure. In Germany, doctors are enthusiastic about the benefits of ginkgo. A combination of ginkgo and ginseng called Gincosan is claimed to produce very good results in elderly patients.
Three months of treatment with a Ginkgo biloba product (240mg per day) maintained attention, memory and functioning – without adverse effects – in a double-blind, placebo-controlled study of 23 patients with mild multiple sclerosis. Deterioration of function was observed in patients who had received a placebo. [American Academy of Neurology 54th Annual Meeting, April 13-20, 2002, Denver, Colorado, USA; P06.081]
In a double-blind German study, ginkgo biloba was significantly superior to a placebo in improving symptoms of intermittent claudication [Peters, 1998]. After six months of treatment, pain-free walking distance in the ginkgo group improved by almost 50% compared to baseline measurements.
One effect of Ginkgo extract is that of promoting vasodilation and blood flow.
Ginkgo Biloba appears to reduce the risk of macular degeneration. [Recent Results in Pharmacology and Clinic, Fuenfgeld FW, ed. Berlin: Springer-Verlag, 1988; pp.231-6]
Ginkgo biloba extract contains substances similar to isoflavone in soy, raising the theoretical possibility that this herb may also have some degree of bone protection; studies regarding this potential use had not been conducted at time of writing.
Studies show that taking Gingko biloba herbal extract at 240mg daily (usually a 24% extract) can produce improvement in 6 months or fewer, even if previous medications have failed. In a study of 20 patients who had received this conventional therapy, 100% regained the ability to have a spontaneous and sustained erection within 6 months of supplementation. Blood flow into the penis improved within 3 months. [Journal of Sex Education Therapy, Vol. 17, 1991, pp.53-61]
A double-blind placebo-controlled study of 67 people with vertigo found that 160mg of Ginkgo biloba extract per day significantly reduced symptoms compared to placebo. At the end of the 3-month study, 47% of the ginkgo group had completely recovered, as compared to only 18% of the placebo group.[ Presse Med. 1986;15: pp.1569-72]
Studies have shown a range of responses from nothing more than a placebo to an effectiveness rate of 50%. Gingko must be administered long term (many months) to achieve benefit. Amongst patients suffering from cerebrovascular insufficiency, a common problem associated with normal aging, a gingko extract produced a significant improvement in the symptoms of vertigo, tinnitus, headache and forgetfulness.
Idiopathic cyclic edema is characterized by water and sodium retention with secondary hyperaldosteronism (over-production of aldosterone) due to capillary hyperpermeability. This defect is detected and measured by the Landis' labeled albumin test; correcting it is important. Ginkgo biloba extract administered either orally or by intravenous infusion provided full correction of this biological anomaly in 10 cases in which the Landis' test was performed before and after oral treatment, and in 5 cases treated by intravenous infusion. [Presse Med 1986 Sep 25;15(31): pp.1550-3 (translated)]
Reduces platelet aggregation.
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