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Botanical Name: Ginkgo biloba
Common Names: Maidenhair tree
Ginkgo (Ginkgo biloba) is one of the oldest living tree species and its
leaves are among the most extensively studied botanicals in use today. Unlike
many other medicinal herbs, ginkgo leaves are not frequently used in their crude
state, but rather, in the form of a concentrated, standardized ginkgo biloba
extract (GBE). In Europe, GBE is among the best-selling herbal medications and
it ranks within the top five of all prescriptions written in France and Germany.
Ginkgo has been used in traditional medicine to treat circulatory disorders
and enhance memory. Scientific studies throughout the years lend support to
these traditional uses. Emerging evidence suggests that GBE may be particularly
effective in treating ailments associated with decreased blood flow to the
brain, particularly in elderly individuals. Laboratory studies have shown that
GBE improves blood circulation by dilating blood vessels and reducing the
stickiness of blood platelets.
Ginkgo leaves also contain two types of chemicals (flavonoids and terpenoids)
believed to have potent antioxidant properties. Antioxidants are substances that
scavenge free radicals -- damaging compounds in the body that alter cell
membranes, tamper with DNA, and even cause cell death. Free radicals occur
naturally in the body, but environmental toxins (including ultraviolet light,
radiation, cigarette smoking, and air pollution) can also increase the number of
these damaging particles. Free radicals are believed to contribute to a number
of 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 neutralize free radicals and may reduce or even help prevent some of the
damage they cause.
Based on studies conducted in laboratories, animals, and humans, professional
herbalists may recommend ginkgo for the following health problems:
Ginkgo is widely used in Europe for treating dementia. The reason that ginkgo
is thought to be helpful for preventing or treating these brain disorders is
because it improves blood flow in the brain and because of its antioxidant
properties. Although many of the clinical trials have been scientifically
flawed, the evidence that ginkgo may improve thinking, learning, and memory in
people with Alzheimer's disease (AD) has been highly promising.
Clinical studies suggest that ginkgo provides the following benefits for
people with AD:
- Improvement in thinking, learning, and memory
- Improvement in activities of daily living
- Improvement in social behavior
- Fewer feelings of depression
One recent study also found that ginkgo may be as effective as leading AD
medications in delaying the symptoms of dementia in people with this
debilitating condition. In addition, ginkgo is sometimes used preventively
because it may delay the onset of AD in someone who is at risk for this type of
dementia (for example, family history).
Eye problems
The flavonoids found in ginkgo may help halt or lessen some retinal problems
(that is, problems to the back part of the eye). Retinal damage has a number of
potential causes, including diabetes and macular degeneration. Macular
degeneration (often called age-related macular degeneration or ARMD) is a
progressive, degenerative eye disease that tends to affect older adults and is
the number one cause of blindness in the United States. Studies suggest that
ginkgo may help preserve vision in those with ARMD.
Intermittent Claudication
Because ginkgo is reputed to improve blood flow, this herb has been studied
in people with intermittent claudication (pain caused by inadequate blood flow
[atherosclerosis] to the legs). People with intermittent claudication have
difficulty walking without suffering 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 leading medication in improving pain-free walking distance.
However, regular walking exercises are more beneficial than ginkgo in improving
walking distance.
Memory Impairment
Ginkgo is widely touted as a "brain herb" and is commonly added to nutrition
bars and fruit smoothies to boost memory and enhance cognitive performance.
Researchers recently reviewed all of the high-quality published studies on
ginkgo and mild memory impairment (in other words, people without Alzheimer's or
other form of dementia), and concluded that ginkgo was significantly more
effective than placebo in enhancing memory and cognitive function. Despite the
encouraging findings, some researchers speculate that more high-quality
research, involving larger numbers of people, is needed before ginkgo can be
recommended as a memory enhancer to otherwise healthy adults.
Tinnitus
Given that nerve damage and certain blood vessel disorders can lead to
tinnitus (the perception of ringing, hissing, or other sound in the ears or head
when no external sound is present), some researchers have investigated whether
ginkgo relieves symptoms of this hearing disorder. Although the quality of most
studies was poor, the reviewers concluded that ginkgo moderately relieves the
loudness of the tinnitus sound. However, a recent well-designed study including
1,121 people with tinnitus found that ginkgo (given 3 times daily for 3 months)
was no more effective than placebo in relieving symptoms of tinnitus. Given
these conflicting findings, the therapeutic value of ginkgo for tinnitus remains
uncertain. In general, tinnitus is a very difficult problem to treat. Talk to
your doctor about whether a trial of ginkgo to alleviate this frustrating
symptom may be safe and worthwhile for you.
Other Uses including Ginkgo for
Depression
In addition to these health problems, professional herbalists may also
recommend ginkgo for a variety of other ailments including altitude sickness,
asthma, depression, disorientation, headaches, high blood pressure, erectile
dysfunction, and vertigo.
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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 edible inner seed.
Although Chinese herbal medicine has used both the ginkgo leaf and seed for
centuries, modern research has focused on the standardized Ginkgo biloba extract
(GBE), which is prepared from the dried green leaves. This extract is highly
concentrated and much more effective in treating health problems (particularly
circulatory ailments) than the leaf alone.
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More than 40 components of ginkgo have been identified but only two are
believed to be responsible for the herb's beneficial effects -- flavonoids and
terpenoids. As described earlier, flavonoids (such as quercetin) have potent
antioxidant effects. Laboratory and animal studies have shown that flavonoids
protect the nerves, heart muscle, and retina from damage. Terpenoids (such as
ginkgolides) improve blood flow by dilating blood vessels and reducing the
stickiness of platelets.
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- Ginkgo biloba extract (GBE) standardized to contain 24% flavonoids and
6% terpenoids
- Capsules
- Tablets
- Tictures
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How to Take It
Pediatric
There are no known scientific reports on the pediatric use of ginkgo.
Therefore, it is not currently recommended for children.
Adult
- Initial results often take 4 to 6 weeks, but should continue to
accumulate beyond that period. You may not see any dramatic changes for six
months.
- GBE: 120 mg daily in two or three divided doses of 50:1 extract
standardized to 24% flavone glycosides (flavonoids). If more serious
dementia or Alzheimer's disease is present, up to 240 mg daily in two or
three divided doses may be necessary.
- Tincture (1:5): 2 to 4 mL three times a day
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The use of herbs is a time-honored approach to strengthening the body and
treating disease. Herbs, however, contain active substances 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
practitioner knowledgeable in the field of botanical medicine.
GBE is considered to be safe and side effects are rare. In a few cases,
gastrointestinal upset, headaches, skin reactions, and dizziness were reported.
Because gingko decreases platelet aggregation (stickiness), there is some
concern that it may increase risk of intracranial (brain) hemorrhage. In fact,
there have been several reports of bleeding complications associated with ginkgo
use. However, it is not clear whether ginkgo or another factor (such as the
combination of ginkgo and blood-thinning medications including aspirin) caused
the bleeding complications.
Pregnant and breastfeeding women should avoid using ginkgo preparations. In
addition, ginkgo use should be discontinued at least 36 hours prior to surgery
due to the risk of bleeding complications.
Do not ingest Ginkgo biloba fruit.
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If you are currently being treated with any of the following medications, you
should not use ginkgo without first talking to your healthcare provider:
Ginkgo and Anticonvulsant medications
High doses of Ginkgo biloba could decrease the effectiveness of
anticonvulsant therapy in patients taking carbamazepine or valproic acid to
control seizures.
Ginkgo and Blood-thinning medications
Ginkgo has blood-thinning properties and therefore should not be used if you
are taking anticoagulant (blood-thinning) medications, such as aspirin,
clopidogrel, dipyridamole, heparin, ticlopidine, or warfarin.
Ginkgo and Cylosporine
Ginkgo biloba may be beneficial during treatment with cyclosporine because of
its ability to protect cell membranes from damage.
Ginkgo and MAOIs (Monoamine oxidase inhibitors)
Ginkgo may enhance the effects (both good and bad) of antidepressant
medications known as MAOIs, such as phenelzine and tranylcypromine.
Ginkgo and Papaverine
The combination of papaverine and ginkgo may be effective for the treatment
of erectile dysfunction in patients who do not respond to papaverine alone.
Ginkgo and Thiazide diuretics
Although there has been one literature report of increased blood pressure
associated with the use of ginkgo during treatment with thiazide diuretics, this
interaction has not been verified by clinical trials. Nevertheless, you should
consult with your healthcare provider before using ginkgo if you are taking
thiazide diuretics.
Ginkgo and Trazodone
Additionally, there has been a report of an adverse interaction between
ginkgo and trazodone, an antidepressant medication, that resulted in an elderly
patient going into a coma.
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Reviewed: 02/2006
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