As a matter of fact I am so impressed that I have planted three ginkgo trees for my own use.
The Ginkgo tree species has survived for over 150 million years and some trees live to over 1000 years. It is sometimes called a living fossil. It has been used for memory, circulation, hearing problems, allergic reactions and to preserve general health and vitality.
Ginkgo is a herb widely used in Europe to improve memory and cognitive function and also in the treatment of intermittent claudication, a vascular constriction disorder of the lower legs that results in calf pain upon exertion. It is also used in the treatment of tinnitus. For a herb, ginkgo is pretty well studied. In this case, that means that there are more than two dozen double blind, placebo controlled trials in humans and quite a few animal studies.
Medical claims for the herb *are* supported by these studies. In essence, ginkgo is a mild vasodilator, and part of its effects on cognition are probably from increased blood flow in the brain. However, it has some effects directly on memory itself (as opposed to increasing attention as stimulants do) that appear unrelated to its vaso- dilating properties and so is of interest to researchers investigating Alzheimer's Disease. ginkgo also has antioxidant properties; some European physicians are using it to limit tissue damage after strokes, apparently with good results. Some people with learning disabilities report that it's helpful, although this particular use has never been studied in humans. People with memory and concentration problems from Chronic Fatigue Syndrome, Fibromyalgia Syndrome, closed head trauma and other diseases are currently experimenting with this herb to see if it can improve their mental performance. No formal studies are available on this use. There does not appear to be any evidence to support the idea that it's a cognitive enhancer or 'smart drug' in non-impaired persons.
It is possible that ginkgo may be effective in the treatment of certain sexual dysfunctions. An article a few years ago in a leading urology journal found that it was more effective than placebo in the treatment of male erectile difficulties. The author attributes the effect to ginkgo's vasodilating properties and believes that the increased blood flow to the penis was aiding erection. More recently, a psychiatrist in San Francisco has been using ginkgo to treat sexual dysfunction related to the use of SSRI antidepressants. He presented a poster session at the last American Psychological Association conference of the results of this treatment in 80 people. However, he did not use a control group. It's not clear whether this applies to women. Unfortunately, there are very few studies on drug related sexual dysfunction in women. We do know that yohimbine, a drug that is somewhat effective in male sexual disorders, appears ineffective in women. Additionally, hormonal therapies for men and women differ somewhat, so we cannot simply assume that what works for a man will work for a woman. However, women do also possess genital erectile tissues; the use of vasodilators in sexual dysfunction is a very intriguing idea and I would very much like to see a controlled study on this application of ginkgo, especially in women.
Ginkgo has a long history of use in Chinese herbalism. However, Chinese herbalists usually use the seed rather than the leaf (used in European extracts). Chinese herbalists also use ginkgo in different amounts and for indications that are not directly translatable to scientific medicine. Large amounts of ginkgo need to be used to get a pharmacologic effect; therefore. it is best used in extract form. Virtually all the studies have been done using one extract from a French company. This extract is standardized to 24% isoflavones and 6% terpines, mostly ginkgolides. I don't know the name of the French company; however, it's relatively easy to come across 24% standardized liquid extracts in either alcohol or (for recovering alcoholics ) vegetable glycerine. Any claims made for ginkgo apply ONLY to this form. All bets are off for other versions. According to the Herb Research Foundation, the effective dose appears to be around 120 mg. to 160 mg per day. This figure refers to the dosage of flavones and ginkgolides and not to raw herb or total extract. It can take up to 6-8 weeks for cognitive effects to be noticed, although vasodilating effects (and side-effects) can be noticed much earlier.
Ginkgo is generally regarded as very safe, even by the US FDA, which is quite conservative on the subject. However, like most herbs, there's not a PDR that you can consult that tells you what the counterindications and drug interactions are. There are no reports of adverse effects in the scientific literature; however, I have encountered anecdotes of ginkgo lowering blood pressure to the point of dizziness and it does appear to increase the effects of vasodilating medications for high blood pressure. One elderly woman who took ginkgo after a stroke developed dizziness and low blood pressure. She told me that, even though she completely stopped the ginkgo immediately, it took 10 days for the side effect to go away. Her situation is far from typical: nonetheless others may also find that it takes several days for ginkgo related side effects to go away. I am unaware of adverse interactions with SSRIs or other anti-depressants. If anecdotes are of any value, my husband takes ginkgo along with bupropion for ADD and has never had a problem. Of course, n=1 is not exactly a great clinical study. :) Of greater concern is the fact that ginkgo decreases platelet agglutination and therefore increases the time it takes for blood to clot. This is not cause for panic: aspirin does the same thing, which actually makes it useful as a preventative and emergency treatment for myocardial infarction (heart attack). It is now standard to tell people who think are having a heart attack to immediately call the paramedics and then take one aspirin. Doctors also tell people who are at risk of heart attack to take one baby aspirin a day. However: Aspirin does increase the risk of stroke from a broken blood vessel in the brain. This is called a hemorrhagic stroke (as opposed to an ischemic stroke which is caused by atherosclerotic blockage of blood supply to the brain) and is the reason why doctors are not telling every person to take aspirin to protect the heart. I have been unable to find out how the anti-clotting effects of ginkgo compare to those of aspirin. (which seems to me like a reasonable standard of comparison since most folks are pretty familiar with aspirin). There is debate among pharmacognosy researchers and the scientific end of medical herbalism community about whether ginkgo can increase the risk of hemorrhagic strokes.
There have been a couple of anecdotal reports of hemorrhagic stroke from herbalists on the phytopharmacognosy list, but we don't know for sure if they're related to ginkgo or not. Many people who take ginkgo are elderly, and so already at increased risk of stroke. I think the risk of stroke from ginkgo, if any, is pretty small. However, until a properly conducted study is done in humans we can't know for sure. My own recommendation, being fairly cautious, is that it should not be used in persons post head trauma or hemorrhagic stroke, although it's probably helpful in ischemic stroke. It also should not be used by persons with bleeding disorders or on anticoagulants. Persons on blood pressure medications should have their blood pressure closely monitored. Taking blood pressure medication doesn't mean that a person cannot take ginkgo, but the drug dosage may need to be adjusted downwards and there may be unpleasant side effects like increased fatigue during this process. More detailed chemical information on ginkgo for the technically minded: To quote from the American Botanical Council pamphlet on ginkgo: "(ginkgo) preparations currently available on the world market include dried leaf, tinctures, homeopathic preparations and various extracts, The leaves are a rich complex of chemical structures. Active constituents include bioflavonoids, such as the flavonoid glycosides kaempferol, quercetin and isorhamnetine; flavones; and organic acids. Novel dieterpene lactones, unique to ginkgo are currently the focus of intensive pharmacological and clinical research. These include the ginkgolides (A,B,C and M) and bilobalide, a sesquiterpene. The ginkgolides, bitter diterpene principles of the leaves and roots were first isolated in 1932 by Furukawa. The chemical structure of ginkgolides was elucidated and named by Japanese researchers Nakanishi et al., in 1966.
They are extremely complex molecules unique to ginkgo...Using a highly complex multistep procedure, E.Corey et al., chemists at Harvard University, succeeded in completely synthesizing ginkgolide B in 1988. .... The various ginkgolides have different degrees of potency. Ginkgolide B is considered the most active. They are very selective antagonists of platelet aggregation induce by platelet-activating-factor (PAF), an inflammatory autGinkgo biloba (courtesy of Herbanet)
I have seen MRI brain images of patients who are under Ginkgo extract treatment, there was an obvious blood circulation differences between before and after treatment images. Main active constituents of Ginkgo are a special type of sesquiterpene lactones, ginkgolides. Obviously other constituents such as biflavonoids also have beneficial effectson the circulatory system, however, much of the pharmacological effects of Ginkgo extract is due to ginkgolides. please refer to: Gingkgolides, Chemistry, Biology, Pharmacology and Clinical Perspectives, Volume 1, 794 pgs., P. Braquet (Edit.), J. R. Prous Science Publishers (1988) and C. Bruno et al., "Regeneration of Motor Nerves in Bilobalide-Treated Rats", Planta Medica 59, 302-307 (1993). M. Miski
Ginkgo biloba: * botanical name(s): Ginkgo biloba
* synonyms: ginkgo tree, maidenhair tree
* part(s) used: leaves and nut
* qualities: bitter, neutral; associated with Mercury* actions: > nut: expectorant, stops discharges > leaves: relaxation of blood vessels, antioxidant, inhibits platelet aggregation, increases peripheral and cerebral blood flow, cardiovascular tonic, brain tonic
* dosage: note: the clinical research on efficacy of Ginkgo all utilized extracts which are standardized to 24% of the heteroside flavonoids. In order to get a therapeutically effective concentration of flavonoids from an alcohol tincture of Ginkgo, the equivalent dose of 1 oz. q.d. would contain tannins in concentrations able to cause gastrointestinal distress. > tincture: 1 - 4 ml.; see above note > powder: 400 - 1600 mg > capsules: 2 - 4 up to t.i.d.
* therapy: > nut: wheezing and coughing with sputum, leukorrhea, urinary incontinence > leaves: arterial insufficiency, ischemic heart disease, peripheral vascular disease (it affects both arteries and veins); failing mental faculties; tinnitus * toxicity: 1; see tannin toxidrome
* constituents: lignans, flavonoids, mainly flavone glycosides; terpenes, traces of essential oil, tannins, organic acids, carotenoids * no contraindications, although a case was reported of an increase in pre-existing hypotension compounds (Baer, p. 165 (Kinghorn); Muenscher, p. 12)
* handling of the fresh fruit may cause contact dermatitis due to its phenolic * improperly prepared fruits or seeds may act as a nauseant, and damage the liver and kidneys (Westbrooks and Preacher, p. 6; Altonen).