Based on studies conducted in laboratories, animals, and humans, ginkgo is used for the following:
Dementia and Alzheimer's disease
Ginkgo is widely used in Europe for treating dementia. It was first used because it improves blood flow to the brain. Now further study suggests it may directly 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.
Clinical studies suggest that ginkgo may have 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 work as well 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 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 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.
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 revealed that people taking ginkgo tend to walk about 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 work better than ginkgo in improving walking distance.
One small study found that people with glaucoma who took 120 mg of ginkgo daily for 8 weeks had improvements in their vision.
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 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 no effect on memory. The most effective dose seems to be 240 mg per day. Ginkgo is commonly added to nutrition bars, soft drinks, and fruit smoothies to boost memory and enhance mental performance, although it's unlikely that such small amounts of ginkgo would work.
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 ginkgo may help preserve vision in those with ARMD.
Nerve damage and certain blood vessel disorders can lead to tinnitus -- ringing, hissing, or other sound in the ears or head. Because ginkgo improves circulation, it has been studied to see whether it can treat tinnitus. A few poorly designed studies found it might reduce the loudness of the sound. However, a well-designed study including 1,121 people with tinnitus found that ginkgo was no better than placebo in relieving tinnitus symptoms. In general, tinnitus is a very difficult problem to treat.
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.
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 metabolized 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 drugs to control seizures, such as carbamazepine (Tegretol) or valproic acid (Depakote), less effective.
Antidepressants -- Taking ginkgo along with a kind of antidepressant called selective serotonin reuptake inhibitors (SSRIs) may increase the risk of serotonin syndrome, a potentially fatal condition. Ginkgo may strengthen both the good and bad effects of antidepressant medications known as MAOIs, such as phenelzine (Nardil). SSRIs include:
- Citalopram (Celexa)
- Escitalopram (Lexapro)
- Fluoxetine (Prozac)
- Fluvoxamine (Luvox)
- Paroxetine (Paxil)
- Sertraline (Zoloft)
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 arrhythmias.
Blood-thinning medications -- Ginkgo may raise the risk of bleeding, especially if you take blood-thinners such as warfarin (Coumadin), clopidogrel (Plavix), and aspirin.
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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