Ginkgo (Ginkgo biloba; in Chinese and Japanese , pinyin romanization: y�n x�ng, Hepburn romanization: ichō or ginnan), also spelled gingko, also known as the Maidenhair Tree after Adiantum, is a unique species of tree with no close living relatives. The ginkgo is classified in its own division, the Ginkgophyta, comprising the single class Ginkgoopsida, order Ginkgoales, family Ginkgoaceae, genus Ginkgo and is the only extant species within this group. It is one of the best-known examples of a living fossil, because Ginkgoales other than G. biloba are not known from the fossil record after the Pliocene.
For centuries it was thought to be extinct in the wild, but is now known to grow in at least two small areas in Zhejiang province in Eastern China, in the Tian Mu Shan Reserve. However, recent studies indicate high genetic uniformity among ginkgo trees from these areas, arguing against a natural origin of these populations and suggesting that the ginkgo trees in these areas may have been planted and preserved by Chinese monks over a period of about 1000 years. Whether native ginkgo populations still exist has not been demonstrated unequivocally.
The relationship of Ginkgo to other plant groups remains uncertain. It has been placed loosely in the divisions Spermatophyta and Pinophyta, but no consensus has been reached. Since Ginkgo seeds are not protected by an ovary wall, it can morphologically be considered a gymnosperm. The apricot-like structures produced by female ginkgo trees are technically not fruits, but are seeds that have a shell that consists of a soft and fleshy section (the sarcotesta), and a hard section (the sclerotesta).
Ginkgos are very large trees, normally reaching a height of 20–35 m (66–115 feet), with some specimens in China being over 50 m (164 feet). The tree has an angular crown and long, somewhat erratic branches, and is usually deep rooted and resistant to wind and snow damage. Young trees are often tall and slender, and sparsely branched; the crown becomes broader as the tree ages. During autumn, the leaves turn a bright yellow, then fall, sometimes within a short space of time (1–15 days). A combination of resistance to disease, insect-resistant wood and the ability to form aerial roots and sprouts makes ginkgos long-lived, with some specimens claimed to be more than 2,500 years old.
Ginkgo is a relatively shade-intolerant species that (at least in cultivation) grows best in environments that are well-watered and well-drained. The species shows a preference for disturbed sites; in the "semi-wild" stands at Tian Mu Shan, many specimens are found along stream banks, rocky slopes, and cliff edges. Accordingly, Ginkgo retains a prodigious capacity for vegetative growth. It is capable of sprouting from embedded buds near the base of the trunk (lignotubers, or basal chi chi) in response to disturbances, such as soil erosion. Old individuals are also capable of producing aerial roots (chi chi) on the undersides of large branches in response to disturbances such as crown damage; these roots can lead to successful clonal reproduction upon contacting the soil. These strategies are evidently important in the persistence of Ginkgo; in a survey of the "semi-wild" stands remaining in Tian Mu Shan, 40% of the Ginkgo specimens surveyed were multi-stemmed, and few saplings were present.
Ginkgo (Ginkgo biloba) is one of the oldest living tree species and its leaves are among the most extensively studied botanicals in use today. In Europe and the United States, ginkgo supplements are among the best-selling herbal medications. It consistently ranks as a top medicine prescribed in France and Germany.
Ginkgo has been used in traditional medicine to treat circulatory disorders and enhance memory. Scientific studies throughout the years have found evidence to support these uses. Although not all studies agree, ginkgo may be especially effective in treating dementia (including Alzheimer's disease) and intermittent claudication (poor circulation in the legs). It also shows promise for enhancing memory in older adults. Laboratory studies have shown that ginkgo improves blood circulation by dilating blood vessels and reducing the stickiness of blood platelets.
Ginkgo leaves contain two types of chemicals (flavonoids and terpenoids) believed to have potent antioxidant properties. Antioxidants are substances that scavenge free radicals -- compounds in the body that damage cell membranes, tamper with DNA, and even cause cell death. Free radicals occur naturally in the body and grow in number as we age. But environmental toxins (including ultraviolet light, radiation, cigarette smoking, and air pollution) can also increase the number of free radicals. Free radicals are believed to contribute to health problems including heart disease and cancer as well as Alzheimer's disease and other forms of dementia. Antioxidants such as those found in ginkgo can help neutralize free radicals and may reduce or even help prevent some of the damage they cause.
Plant Description:
Ginkgo biloba is the oldest living tree species. A single tree can live as long as 1,000 years and grow to a height of 120 feet. It has short branches with fan-shaped leaves and inedible fruits that produce a strong odor. The fruit contains an inner seed, and there has been a report of a human poisoning from ingesting the seed. Ginkgos are tough, hardy trees and are sometimes planted along urban streets in the United States.
Although Chinese herbal medicine has used both the ginkgo leaf and seed for thousands of years, modern research has focused on the standardized Ginkgo biloba extract (GBE), which is prepared from the dried green leaves. This standardized extract is highly concentrated and seems to be clinically more effective in treating health problems (particularly circulatory ailments) than the non-standardized leaf alone.
What's It Made Of?:
More than 40 components isolated from the ginkgo tree have been identified, but only two are believed to be responsible for the herb's medicinal effects: flavonoids and terpenoids. Flavonoids are plant-based antioxidants. Laboratory and animal studies have shown that flavonoids protect the nerves, heart muscle, blood vessels, and retina from damage. Terpenoids (such as ginkgolides) improve blood flow by dilating blood vessels and reducing the stickiness of platelets.
Medicinal Uses and Indications:
Based on studies conducted in laboratories, animals, and humans, gingko is used for the following:
Dementia and Alzheimer's disease
Ginkgo is widely used in Europe for treating dementia. It was used originally because it improves blood flow to the brain. Now further study suggests it may work directly to protect nerve cells that are damaged in Alzheimer's disease. A number of studies have found that gingko has a positive effect on memory and thinking in people with Alzheimer's or vascular dementia.
Clinical studies suggest that ginkgo may provide the following benefits for people with Alzheimer's disease:
Improvement in thinking, learning, and memory (cognitive function)
Improvement in activities of daily living
Improvement in social behavior
Fewer feelings of depression
Several studies have found that ginkgo may be as effective as prescription Alzheimer's medications in delaying the symptoms of dementia.
However, one of the longest and best-designed studies found ginkgo was no better than placebo in reducing Alzheimer's symptoms. In a 2008 study, 176 people in the United Kingdom with Alzheimer's took either ginkgo or placebo for 6 months. At the end of the study there was no difference in cognitive function or quality of life between the groups.
Ginkgo is sometimes suggested to prevent Alzheimer's and dementia, as well, and some studies have suggested it might be helpful. But in 2008, a well-designed study (the GEM study) with more than 3,000 elderly participants found the ginkgo was no better than placebo in preventing dementia or Alzheimer's.
Intermittent Claudication
Because ginkgo improves blood flow, it has been studied in people with intermittent claudication (pain caused by reduced blood flow to the legs). People with intermittent claudication have a hard time walking without feeling extreme pain. An analysis of eight published studies revealed that people taking ginkgo tend to walk roughly 34 meters farther than those taking placebo. In fact, ginkgo has been shown to be as effective as a prescription medication in improving pain-free walking distance. However, regular walking exercises are more beneficial than ginkgo in improving walking distance.
Glaucoma
One small study found that people with glaucoma who took 120 mg of ginkgo daily for 8 weeks had improvements in their vision.
Memory Enhancement
Ginkgo is widely touted as a "brain herb." It has been studied to see whether it can improve memory in people with dementia, and some studies found it did help. It's less clear whether ginkgo helps improve memory in healthy people who experience normal memory loss that comes with age. Some studies have found slight benefits, while other studies have found no effect on memory. The most effective dose seems to be greater than or equal to 240 mg per day. Ginkgo is commonly added to nutrition bars, soft drinks, and fruit smoothies to boost memory and enhance cognitive performance, although it's doubtful that such small amounts of gingko would be effective.
Macular Degeneration
The flavonoids found in ginkgo may help stop or lessen some retinal problems (problems with the back part of the eye). Macular degeneration (often called age-related macular degeneration or ARMD) is an eye disease that affects the retina. It is a progressive, degenerative eye disease that tends to affect older adults and is the number one cause of blindness in the United States. Some studies suggest that gingko may help preserve vision in those with ARMD.
Tinnitus
Nerve damage and certain blood vessel disorders can lead to tinnitus (ringing, hissing, or other sound in the ears or head when no external sound is present). Because ginkgo improves circulation, it has been studied to see whether it can treat tinnitus. A few poorly designed studies found it might moderately relieve the loudness of the tinnitus sound. However, a well-designed study including 1,121 people with tinnitus found that ginkgo (taken 3 times daily for 3 months) was no more effective than placebo in relieving symptoms of tinnitus. In general, tinnitus is a very difficult problem to treat.
Other
A standardized ginkgo extract was reported to significantly improve functional measures (such as coordination, energy level, strength, mental performance, mood, and sensation) in 22 people with multiple sclerosis (MS).
Available Forms:
Standardized extracts containing 24 - 32% flavonoids (also known as flavone glycosides or heterosides) and 6 - 12% terpenoids (triterpene lactones)
Capsules
Tablets
Liquid extracts (tinctures, fluid extracts, glycerites)
Dried leaf for teas
How to Take It:
Pediatric
Ginkgo is not generally used in children.
Adult
Initial results often take 4 - 6 weeks, but should grow stronger beyond that period.
Memory impairment and cardiovascular function: Generally, 120 mg daily in divided doses, standardized to contain 24 - 32% flavone glycosides (flavonoids or heterosides) and 6 - 12% triterpene lactones (terpenoids). If more serious dementia or Alzheimer's disease is present, up to 240 mg daily, in 2 or 3 divided doses, may be necessary.
Intermittent claudication: 120 - 240 mg per day
Precautions:
The use of herbs is a time-honored approach to strengthening the body and treating disease. Herbs, however, contain components that can trigger side effects and interact with other herbs, supplements, or medications. For these reasons, herbs should be taken with care, under the supervision of a health care provider qualified in the field of botanical medicine.
GBE is generally considered to be safe, and side effects are rare. In a few cases, gastrointestinal upset, headaches, skin reactions, and dizziness were reported.
There have been a number of reports of internal bleeding in people who take ginkgo. However, it is not clear whether ginkgo was responsible or whether there was another cause (whether a combination of ginkgo and blood-thinning drugs caused the bleeding, for example). One human study found that ginkgo significantly prolonged bleeding time when given along with cilostazol (Pletal), a commonly used blood-thinner. However, other studies found that gingko combined with warfarin (Coumadin) did not prolong bleeding time. Because of the uncertainty, you should ask your doctor before taking gingko if you also take blood-thinning drugs.
If you take gingko, you should stop taking it at least 36 hours prior to surgery or dental procedures due to the risk of bleeding complications. Tell your doctor or dentist that you take gingko.
People who have epilepsy should not take gingko, because there is concern that it might cause seizures.
Pregnant and breastfeeding women should not take gingko.
Do not eat Ginkgo biloba fruit or seed.
Possible Interactions:
Ginkgo may alter the metabolism and effectiveness of some prescription and non-prescription medications. If you are being treated with any of the following medications, you should not use ginkgo without first talking to your health care provider:
Anticonvulsant medications -- High doses of ginkgo could make drugs to control seizures, such as carbamazepine (Tegretol) or valproic acid (Depakote), less effective.
Antidepressants -- Taking ginkgo along with selective serotonin reuptake inhibitor (SSRIs) antidepressants may increase the risk of serotonin syndrome, a potentially fatal condition. Ginkgo may enhance the effects (both good and bad) of antidepressant medications known as MAOIs, such as phenelzine (Nardil). SSRIs include:
Citalopram (Celexa)
Escitalopram (Lexapro)
Fluoxetine (Prozac)
Fluvoxamine (Luvox)
Paroxetine (Paxil)
Sertraline (Zoloft)
Antihypertensive (blood pressure) medications -- Ginkgo may lower blood pressure. For that reason, if you take medication to lower your blood pressure you should ask your doctor before taking gingko. There has been a report of an interaction between ginkgo and nifedipine (Procardia), a calcium channel blocker used for blood pressure and arrhythmias.
Blood-thinning medications -- Ginkgo has blood-thinning properties and should not be used if you are taking anticoagulant (blood-thinning) medications. There has been bleeding in the brain reported when using a ginkgo product and ibuprofen (Advil), a non-steroidal anti-inflammatory drug (NSAID). Blood-thinners include:
Aspirin
Clopidogrel (Plavix)
Heparin
Warfarin (Coumadin)
Medications to lower blood sugar -- Ginkgo may increase insulin levels in healthy subjects and decrease insulin levels in people with diabetes. If you have diabetes, you should not use gingko without first talking to your doctor.
Cylosporine -- Ginkgo biloba may help protect the cells of the body during treatment with the drug cyclosporine, which suppresses the immune system.
Thiazide diuretics(water pills) -- There is one report of a person who took a thiazide diuretic and gingko experiencing high blood pressure. If you take thiazide diuretics, ask your doctor before taking gingko.
Trazodone -- There is one report of an elderly Alzheimer's patient going into a coma after taking ginkgo and trazodone (Desyrel), an antidepressant medication.
Alternative Names:
Fossil tree; Kew tree; Maiden hair tree
Reviewed last on: 3/26/2009
Steven D. Ehrlich, NMD, private practice specializing in complementary and alternative medicine, Phoenix, AZ. Review provided by VeriMed Healthcare Network.
Supporting Research
Adams LL, Gatchel RJ, Gentry C. Complementary and alternative medicine: applications and implications for cognitive functioning in elderly populations. Altern Ther HealthMed. 2001;7(2):52-61.
Aruna D, Naidu MU.Pharmacodynamic interaction studies of Ginkgo biloba with cilostazol and clopidogrel in healthy human subjects. Br J Clin Pharmacol. 2006 Sep 29; [Epub ahead of print].
Ashton, A. K., Ahrens, K., Gupta, S., and Masand, P. S. Antidepressant-induced sexual dysfunction and Ginkgo Biloba. Am J Psychiatry. 2000;157(5):836-837.
Benjamin J, Muir T, Briggs K, Pentland B. A case of cerebral haemorrhage-can Ginkgo biloba be implicated? Postgrad Med J. 2001;77(904):112-113.
Birks J, Grimley Evans J. Ginkgo biloba for cognitive impairment and dementia. Cochrane Database Syst Rev. 2009 Jan 21;(1):CD003120. Review.
Bridi, R., Crossetti, F. P., Steffen, V. M., and Henriques, A. T. The antioxidant activity of standardized extract of Ginkgo biloba (EGb 761) in rats. Phytother Res 2001;15(5):449-451.
Cheuvront, S. N. and Carter, R., III. Ginkgo and memory. JAMA. 2-5-2003;289(5):547-548.
Christen Y. Oxidative stress and Alzheimer's disease. Am J Clin Nutr. 2000;71(suppl):621S-629S.
Choi WS, Choi CJ, Kim KS, Lee JH, Song CH, Chung JH, et al. To compare the efficacy and safety of nifedipine sustained release with Ginkgo biloba extract to treat patients with primary Raynaud's phenomenon in South Korea; Korean Raynaud study (KOARA study). Clin Rheumatol. 2009 Jan 22. [Epub ahead of print]
Cieza, A., Maier, P., and Poppel, E. Effects of Ginkgo biloba on mental functioning in healthy volunteers. Arch Med Res. 2003;34(5):373-381.
Davydov L and Stirling AL. Stevens-Johnson syndrome with Ginkgo biloba. J Herbal Pharmacother. 2001;1(3):65-69.
DeKosky ST, Williamson JD, Fitzpatrick AL, Kronmal RA, Ives DG, Saxton JA, et al; Ginkgo Evaluation of Memory (GEM) Study Investigators. Ginkgo biloba for prevention of dementia: a randomized controlled trial. JAMA. 2008 Nov 19;300(19):2253-62. Erratum in: JAMA. 2008 Dec 17;300(23):2730.
Diamond BJ, Shiflett SC, Feiwel N, et al. Ginkgo biloba extract: mechanisms and clinical indications. Arch Phys Med Rehabil. 2000;81:669-678.
Drew S, Davies E. Effectiveness of Ginkgo biloba in treating tinnitus: double blind, placebo controlled trial. BMJ. 2001;322(7278):73.
Engelsen, J., Nielsen, J. D., and Hansen, K. F. [Effect of Coenzyme Q10 and Ginkgo biloba on warfarin dosage in patients on long-term warfarin treatment. A randomized, double-blind, placebo-controlled cross-over trial]. Ugeskr.Laeger. 4-28-2003;165(18):1868-1871.
Ernst E. The risk-benefit profile of commonly used herbal therapies: ginkgo, St. John's wort, ginseng, echinacea, saw palmetto, and kava. Ann Intern Med. 2002;136:42-53.
Fong, K. C. and Kinnear, P. E. Retrobulbar haemorrhage associated with chronic Gingko biloba ingestion. Postgrad.Med.J. 2003;79(935):531-532.
Galluzzi S, Zanetti O, Binetti G, Trabucchi M, Frisoni GB. Coma in a patient with Alzheimer's disease taking low dose trazodone and Ginkgo biloba. J Neurol Neurosurg Psychiatry. 2000;68:679-683.
Hartley, D. E., Elsabagh, S., and File, S. E. Gincosan (a combination of Ginkgo biloba and Panax ginseng): the effects on mood and cognition of 6 and 12 weeks' treatment in post-menopausal women. Nutr Neurosci. 2004;7(5-6):325-333.
Hilton, M. and Stuart, E. Ginkgo biloba for tinnitus. Cochrane Database Syst Rev. 2004;(2):CD003852.
Horsch, S. and Walther, C. Ginkgo biloba special extract EGb 761 in the treatment of peripheral arterial occlusive disease (PAOD)--a review based on randomized, controlled studies. Int.J Clin Pharmacol Ther. 2004;42(2):63-72.
Huang, S. Y., Jeng, C., Kao, S. C., Yu, J. J., and Liu, D. Z. Improved haemorrheological properties by Ginkgo biloba extract (Egb 761) in type 2 diabetes mellitus complicated with retinopathy. Clin.Nutr. 2004;23(4):615-621.
Johnson SK, Diamond BJ, Rausch S, Kaufman M, Shiflett SC, Graves L. The effect of Ginkgo biloba on functional measures in multiple sclerosis: a pilot randomized controlled trial. Explore (NY). 2006;2(1):19-24.
Kampman, K., Majewska, M. D., Tourian, K., et al., A pilot trial of piracetam and ginkgo biloba for the treatment of cocaine dependence. Addict Behav. 2003;28(3):437-448.
Kenney C, Norman M, Jacobson M, and et al. A double-blind, placebo-controlled, modified crossover pilot study of the effects of Ginkgo biloba on cognitive and functional abilities in multiple sclerosis. American Academy of Neurology 54th Annual Meeting. April 13-20 2002;P06.081.
Kim YS, Pyo MK, Park KM, et al. Antiplatelet and antithrombotic effects of a combination of ticlopidine and Ginkgo biloba ext (EGb 761). Thromb Res. 1998;91:33-38.
Kohler, S., Funk, P., and Kieser, M. Influence of a 7-day treatment with Ginkgo biloba special extract EGb 761 on bleeding time and coagulation: a randomized, placebo-controlled, double-blind study in healthy volunteers. Blood Coagul.Fibrinolysis. 2004;15(4):303-309.
LaValle JB, Krinsky DL, Hawkins EB, et al. Natural Therapeutics Pocket Guide. Hudson, OH: LexiComp; 2000:441-442.
Le Bars PL, Kieser M, Itil KZ. A 26-week analysis of a double-blind, placebo-controlled trial of the Ginkgo biloba extract EGb761 in dementia. Dement Geriatr Cogn Disord. 2000;11:230-237.
Mantle D, Pickering AT, Perry AK. Medicinal plant extracts for the treatment of dementia: a review of their pharmacology, efficacy and tolerability. CNS Drugs. 2000;13:201-213.
Mauro, V. F., Mauro, L. S., Kleshinski, J. F., Khuder, S. A., Wang, Y., and Erhardt, P. W. Impact of ginkgo biloba on the pharmacokinetics of digoxin. Am.J Ther 2003;10(4):247-251.
May BH, Lit M, Xue CC, Yang AW, Zhang AL, Owens MD, et al. Herbal medicine for dementia: a systematic review. Phytother Res. 2008 Dec 11;23(4):447-459.
May BH, Yang AW, Zhang AL, Owens MD, Bennett L, Head R, et al. Chinese herbal medicine for Mild Cognitive Impairment and Age Associated Memory Impairment: a review of randomised controlled trials. Biogerontology. 2009 Apr;10(2):109-23. Epub 2008 Aug 21.
Mazza M, Capuano A, Bria P, Mazza S. Ginkgo biloba and donepezil: a comparison in the treatment of Alzheimer's dementia in a randomized placebo-controlled double-blind study. Eur J Neurol. 2006;13(9):981-5.
McCarney R, Fisher P, Iliffe S, van Haselen R, Griffin M, van der Meulen J, Warner J. Ginkgo biloba for mild to moderate dementia in a community setting: a pragmatic, randomised, parallel-group, double-blind, placebo-controlled trial. Int J Geriatr Psychiatry. 2008 Dec;23(12):1222-30.
Meisel, C., Johne, A., and Roots, I. Fatal intracerebral mass bleeding associated with Ginkgo biloba and ibuprofen. Atherosclerosis. 2003;167(2):367.
Moher D, Pham B, Ausejo M, Saenz A, Hood S, Barber GG. Pharmacological management of intermittent claudication: a meta-analysis of randomised trials. Drugs. 2000;59(5):1057-1070.
Nathan, P. J., Harrison, B. J., and Bartholomeusz, C. Ginkgo and memory. JAMA. 2-5-2003;289(5):546-548.
Oh SM, Chung KH. Antiestrogenic activities of Ginkgo biloba extracts. J Steroid Biochem Mol Biol. 2006;100(4-5):167-76.
Persson, J., Bringlov, E., Nilsson, L. G., and Nyberg, L. The memory-enhancing effects of Ginseng and Ginkgo biloba in healthy volunteers. Psychopharmacology (Berl) 2004;172(4):430-434.
Pittler MH, Ernst E. Ginkgo biloba extract for the treatment of intermittent claudication: a meta-analysis of randomized trials. Am J Med. 2000;108(4):276-281.
Schneider LS, DeKosky ST, Farlow MR, Tariot PN, Hoerr R, Kieser M. A randomized, double-blind, placebo-controlled trial of two doses of Ginkgo biloba extract in dementia of the Alzheimer's type. Curr Alzheimer Res. 2005;2(5):541-51.
Trick, L., Boyle, J., and Hindmarch, I. The effects of Ginkgo biloba extract (LI 1370) supplementation and discontinuation on activities of daily living and mood in free living older volunteers. Phytother Res. 2004;18(7):531-537.
Van Dongen, M., van Rossum, E., Kessels, A., Sielhorst, H., and Knipschild, P. Ginkgo for elderly people with dementia and age-associated memory impairment: a randomized clinical trial. J Clin Epidemiol. 2003;56(4):367-376.
Vellas, B., and Grandjean, H. Association of Alzheimer's disease onset with ginkgo biloba and other symptomatic cognitive treatments in a population of women aged 75 years and older from the EPIDOS study. J Gerontol A Biol.Sci.Med Sci. 2003;58(4):372-377.
The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. � 1997- 2010 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.
