Ginkgo (Ginkgo biloba) is one of the oldest living tree species. It is also tops in scientific studies and in purchases. In Europe and the United States, ginkgo supplements are among the best-selling herbal medications.
Ginkgo has a long history of being used in traditional medicine to treat blood disorders and improve memory, and it's best known today as way to potentially keep your memory sharp. There is some scientific evidence to back that up. Laboratory studies have shown that ginkgo improves blood circulation by opening up blood vessels and making blood less sticky. It's also an antioxidant.
For those reasons, ginkgo may improve vein and eye health. Although not all studies agree, ginkgo may help treat dementia (including Alzheimer's disease) and intermittent claudication, or poor circulation in the legs. It may also protect memory in older adults.
Ginkgo leaves have two types of chemicals (flavonoids and terpenoids) that are antioxidants. In your body, harmful particles called free radicals build up as you age, and may contribute to heart disease, cancer, and Alzheimer's disease. Antioxidants like those found in ginkgo fight off free radicals, and stop them from damaging DNA and other cells.
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 smell bad. The fruit has an inner seed, which may be poisonous. Ginkgos are tough, hardy trees and are sometimes planted along urban streets in the United States. The leavesturn brilliant colors in the fall.
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)made from the dried green leaves. This standardized extract is highly concentrated and seems to treat health problems (particularly circulatory problems) better than the non-standardized leaf alone.
What's It Made Of?
Scientists have found more than 40 components in ginkgo. But only two are believed to act as medicine: flavonoids and terpenoids. Flavonoids are plant-based antioxidants. Laboratory and animal studies show 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 people, ginkgo is used for the following:
Dementia and Alzheimer's disease
Ginkgo is widely used in Europe for treating dementia. At first, doctors thought it helped because itimproves blood flow to the brain. Now more study suggests it may protect nerve cells that are damaged in Alzheimer's disease. A number of studies have found that ginkgo has a positive effect on memory and thinking in people with Alzheimer's or vascular dementia.
Studies suggest that ginkgo may help people with Alzheimer's disease:
Several studies have found that ginkgo may work as well as some prescription Alzheimer's medications to delay the symptoms of dementia. It has not been tested against all of the drugs prescribed to treat Alzheimer's.
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 mental 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 help. But in 2008, a well-designed study (the GEM study) with more than 3,000 elderly people found that ginkgo was no better than placebo in preventing dementia or Alzheimer's.
Because ginkgo improves blood flow, it has been studied in people with intermittent claudication, or 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 studies showed that people taking ginkgo tended to walk about 34 meters farther than those taking placebo. In fact, ginkgo has been shown to work as well as a prescription medication in improving pain-free walking distance. However, regular walking exercises work better than ginkgo in improving walking distance.
One preliminary study found that ginkgo might help relieve anxiety. People with generalized anxiety disorder and adjustment disorder who took a specific extract of ginkgo had fewer anxiety symptoms than those who took placebo.
One small study found that people with glaucoma who took 120 mg of ginkgo daily for 8 weeks had improvements in their vision.
Memory and Thinking
Ginkgo is widely touted as a "brain herb." Some studies show that it does help improve memory in people with dementia. It's not as clear whether ginkgo helps memory in healthy people who have normal, age-related memory loss. Some studies have found slight benefits, while other studies have found it didn't help at all. Some studies have found that ginkgo helps improve memory and thinking in young and middle-aged people who are healthy. The dose that works best seems to be 240 mg per day. There's no proof that taking ginkgo will help protect against dementia. Ginkgo is often added to nutrition bars, soft drinks, and fruit smoothies to boost memory and enhance mental performance, although such small amounts probably don't help.
The flavonoids found in ginkgo may help stop or reduce some problems with the retina, the back part of the eye. Macular degeneration, often called age-related macular degeneration or AMD, is an eye disease that affects the retina. The number one cause of blindness in the Unites States, AMD is a degenerative eye disease that gets worse as time goes on. Some studies suggest that ginkgo may help preserve vision in those with AMD.
Premenstrual Syndrome (PMS)
Two studies with a somewhat complicated dosing schedule found that ginkgo helped reduced PMS symptoms. Women in the studies took ginkgo beginning on day 16 of their menstrual cycle and stopped taking it after day 5 of their next cycle, then took it again on day 16.
One well-designed study found that people with Raynaud's phenomenon who took ginkgo over a 10-week period had fewer symptoms than those who took placebo. More studies are needed.
How to Take It
Ginkgo should not be given to children.
It can take4 - 6 weeks to see any effects from ginkgo. Ask your doctor to help you find the right dose.
Memory problems and Alzheimer's disease: Many studies have used 120 - 240 mg daily in divided doses, standardized to contain 24 - 32% flavone glycosides (flavonoids or heterosides) and 6 - 12% triterpene lactones (terpenoids).
Intermittent claudication: Studies have used 120 - 240 mg per day.
The use of herbs is a time-honored approach to strengthening the body and treating disease. Herbs, however, 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.
Ginkgo usually has few side effects. In a few cases, stomach upset, headaches, skin reactions, and dizziness were reported.
There have been reports of internal bleeding in people who take ginkgo. It's not clear whether the bleeding was due to ginkgo or some other reasons, such as a combination of ginkgo and blood-thinning drugs. Researchers arent sure, because different studies have found different results. You should ask your doctor before taking ginkgo if you also take blood-thinning drugs.
Stop taking ginkgo at least 36 hours before surgery or dental procedures due to the risk of bleeding. Tell your doctor or dentist that you take ginkgo.
People who have epilepsy should not take ginkgo, because it might cause seizures.
Pregnant and breastfeeding women should not take ginkgo.
People who have diabetes should ask their doctor before taking ginkgo.
Do not eat Ginkgo biloba fruit or seed.
Ginkgo may interact with some prescription and non-prescription medications. If you are taking any of the following medications, you should not use ginkgo without first talking to your health care provider:
Medications broken down by the liver -- Ginkgo can interact with some medications that are processed through the liver. If you take any prescription medications, ask your doctor before taking ginkgo.
Seizure medications (anticonvulsants) -- High doses of ginkgo could make anti-seizure drugs not work as well. These drgs includecarbamazepine (Tegretol) and valproic acid (Depakote).
Antidepressants -- Taking ginkgo along with a kind of antidepressant called selective serotonin reuptake inhibitors (SSRIs) may increase the risk of serotonin syndrome, a life-threatening condition. Also, ginkgo may strengthen both the good and bad effects of antidepressants known as MAOIs, such as phenelzine (Nardil). SSRIs include:
Medications for high blood pressure -- Ginkgo may lower blood pressure, so taking it with blood pressure medications may cause blood pressure to drop too low. There has been a report of an interaction between ginkgo and nifedipine (Procardia), a calcium channel blocker used for blood pressure and heart rhythm problems.
Blood-thinning medications -- Ginkgo may raise the risk of bleeding, especially if you take blood-thinners such as warfarin (Coumadin), clopidogrel (Plavix), and aspirin.
Alprazolam (Xanax)-- Ginkgo may make Xanax, and drug taken to treat anxiety, not work as well.
Ibuprofen (Advil, Motrin) -- Like ginkgo, the nonsteroidal anti-inflammatory drug (NSAID) ibuprofen also raises the risk of bleeding. There has been bleeding in the brain reported when using a ginkgo product and ibuprofen.
Medications to lower blood sugar -- Ginkgo may raise or lower insulin levels and blood sugar levels. If you have diabetes, you should not use ginkgo 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 ginkgo developing high blood pressure. If you take thiazide diuretics, ask your doctor before taking ginkgo.
Trazodone -- There is one report of an elderly Alzheimer's patient going into a coma after taking ginkgo and trazodone (Desyrel), an antidepressant medication.
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Review Date: 12/13/2010
Reviewed By: Steven D. Ehrlich, NMD, Solutions Acupuncture, a private practice specializing in complementary and alternative medicine, Phoenix, AZ. Review provided by VeriMed Healthcare Network.
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