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Other common name(s):
ginkgo biloba, maidenhair tree, EGb 761
Scientific/medical name(s):
Ginkgo biloba
Description
Ginkgo is an extract of leaves from a ginkgo tree, one of the
world's oldest surviving species of tree, which comes from China,
Japan, and Korea. It is used as a dietary supplement in the United
States for a variety of conditions.
Overview
Ginkgo has shown some benefit in the treatment of mild to
moderate dementia (decline in mental ability). Other studies have shown
that it can help improve blood circulation and flow to the brain. Few
side effects have been reported with its use, but it has the potential
to interfere with blood clotting, anesthesia, and some medications.
Available scientific evidence does not support claims that it is
effective in preventing or treating cancer in humans.
How is it promoted for use?
Ginkgo is promoted as an aid to memory and concentration. Ginkgo is
believed to stimulate blood circulation and the flow of oxygen to the
brain. Widely used in Europe, the extract has since become popular in
the United States. Claims include improved memory and vision in the
elderly and a slowing of the progression of Alzheimer's disease or
dementia.
Ginkgo is sometimes promoted for tinnitus (ringing in the ears), sudden
deafness, dizziness, altitude sickness, and intermittent claudication
(a cramp-like pain in the lower legs due to poor circulation). In
addition, it has been used as a treatment for a blood vessel disorder
known as Raynaud's disease, in which the toes or fingers turn cool and
pale when exposed to cold because of an insufficient blood supply.
European and Asian doctors have also used ginkgo in stroke patients to
see if it would limit tissue damage to the brain.
Although not usually promoted as a cancer treatment, herbalists note
that ginkgo contains some substances that may prove to have activity
against cancer, including flavonoids (which are thought to be
anti-inflammatory) and proanthocyanidins (which are antioxidants). It
also contains a compound called ginkgolide B that may counteract a body
chemical called platelet-activating factor (PAF), which is thought to
promote tumor growth.
What does it involve?
Ginkgo leaf extract is on the Commission E (Germany's
regulatory agency for herbs) list of approved herbs, and can be taken
in pill or liquid form by mouth. The average dose of ginkgo extract is
120 to 240 milligrams (mg) per day, usually divided into 2 to 3 doses.
Proponents usually do not recommend the crude, dried leaf preparations
because they claim they do not contain enough of the active
ingredients.
Chinese herbalists have used the fruit of the ginkgo tree for about
4,000 years as a remedy for asthma, coughs, and allergic reactions.
Cooked ginkgo seeds are also sometimes eaten after the pulp has been
removed from the outside. In the past few decades, an extract of ginkgo
leaves has been used in Western medicine, first in Europe and more
recently in the United States because it is supposed to help memory,
brain function, and blood circulation.
What is the history behind it?
Chinese herbalists have used the fruit of the ginkgo tree for
about 4,000 years as a remedy for asthma, coughs, and allergic
reactions. Cooked ginkgo seeds are also sometimes eaten after the pulp
has been removed from the outside. In the past few decades, an extract
of ginkgo leaves has been used in Western medicine, first in Europe and
more recently in the United States because it is supposed to help
memory, brain function, and blood circulation.
What is the evidence?
Memory and Concentration
Ginkgo leaf extract appears to improve blood flow to the brain. Some,
but not all, studies have found positive results from ginkgo extract on
memory. Most randomized, controlled studies have found that ginkgo
extract can improve cognitive and social function in patients with mild
to moderate dementia resulting from Alzheimer's disease or problems
with blood circulation in the brain. Results of its effects on memory
and concentration in people without dementia have been mixed.
Other Conditions
Some studies have found ginkgo leaf extract may have modest benefits in
patients with claudication or sudden hearing loss. A 2004 review of
studies recently concluded that there was not enough evidence to
support claims that ginkgo can help tinnitus (ringing in the ears).
Cancer
The possible effects of ginkgo leaf extract in preventing or treating
cancer have not been well studied. Some small studies done in Asia have
suggested that ginkgo extract may be active against cancer cells in
culture dishes and lab animals, but no studies have been done to show
it can prevent or treat cancer in humans. A few small studies have
looked at adding ginkgo to other treatments in cancer patients, but the
results have not been conclusive. More research is needed in this area.
Are there any possible problems
or complications?
This product is sold as a dietary supplement in the
United States. Unlike drugs (which must be tested before being allowed
to be sold), the companies that make supplements are not required to
prove to the Food and Drug Administration that their supplements are
safe or effective, as long as they don't claim the supplements can
prevent, treat, or cure any specific disease.
Some such products may not contain the amount of the herb or
substance that is written on the label, and some may include other
substances (contaminants). Actual amounts per dose may vary between
brands or even between different batches of the same brand.
Most such supplements have not been tested to find out if they
interact with medicines, foods, or other herbs and supplements. Even
though some reports of interactions and harmful effects may be
published, full studies of interactions and effects are not often
available. Because of these limitations, any information on ill effects
and interactions below should be considered incomplete.
Ginkgo leaf extract is generally considered safe. Some
possible side effects include headache, mild stomach upset, and
diarrhea. Because of its potential to block platelet-activating factor,
ginkgo is not recommended for people using aspirin, other non-steroidal
anti-inflammatory drugs (such as ibuprofen), or "blood-thinning" drugs
such as warfarin (Coumadin). Doctors often advise stopping its use
several days before surgery. People with seizure disorders are advised
to avoid using ginkgo because it may reduce the effects of seizure
medication. Potential interactions between ginkgo and other drugs and
herbs should be considered. Some combinations may be dangerous. Always
tell your doctor and pharmacist about any herbs you are taking.
Allergic reactions have been reported, including severe skin
reactions with blistering. People who react to poison ivy, mango,
cashews, and sumac may be more likely to react to ginkgo.
Uncooked ginkgo fruit or seed can cause more serious
problems, including vomiting, seizures, and loss of consciousness. The
seed contains a toxin which is reportedly inactivated by cooking.
Poisoning from eating the seeds has been reported in adults and
children, sometimes resulting in death. The fruit/seed is also more
likely to cause allergic rashes and intestinal irritation than the leaf
extract.
This herb has not been studied in women who are pregnant or
breast-feeding.
Relying on this type of treatment alone, and avoiding or
delaying conventional medical care, may have serious health
consequences.
Additional Resources
More Information From Your
American Cancer Society
The following information on complementary and alternative
therapies may also be helpful to you. These materials may be ordered
from our toll-free number (1-800-ACS-2345).
References
Birks J, Grimley EV, Van Dongen M. Ginkgo biloba for
cognitive impairment and dementia. Cochrane
Database Syst Rev. 2002;(4):CD003120.
Blumenthal M, ed.
The Complete German Commission E Monographs: Therapeutic Guide to
Herbal Medicines. Austin, Tx: American Botanical Council;
1998.
Gruenwald J, Brendler T, Jaenicke C, eds. PDR for Herbal Medicines, Third
Edition. Thomson PDR, Montvale NJ, 2004.
Hasegawa S, Oda Y, Ichiyama T, et al. Ginkgo nut intoxication
in a 2-year-old male. Pediatr
Neurol. 2006;35:275-276.
Hilton M, Stuart E. Ginkgo biloba for tinnitus. Cochrane Database Syst Rev.
2004;(2):CD003852.
Le Bars PL, Katz MM, Berman N, et al. A placebo-controlled,
double-blind, randomized trial of an extract of Ginkgo biloba for
dementia. North American Egb Study Group. JAMA.
1997;278:1327-1332.
Memorial Sloan-Kettering Cancer Center. About herbs: Ginkgo.
2006. Available at: http://www.mskcc.org/mskcc/html/69235.cfm. Accessed
April 18, 2007.
Miwa H, Iijima M, Tanaka S, Mizuno Y. Generalized convulsions
after consuming a large amount of gingko nuts. Epilepsia.
2001;42:280-281.
MD Anderson Cancer Center. Patient Monograph: Ginkgo. 2004.
Available at:
www.mdanderson.org/departments/cimer/display.cfm?id=6bf16f2a-7c12-4546-8b39271278bdf215&method=displayfull&pn=6eb86a59-ebd9-11d4-810100508b603a14.
Accessed April 18, 2007.
NCCAM, National Institutes of Health. Ginkgo. Available at:
http://nccam.nih.gov/health/ginkgo/. Accessed April 19, 2007.
Sierpina VS, Wollschlaeger B, Blumenthal M. Ginkgo biloba. Am Fam Physician.
2003;68:923-926.
Suzuki R, Kohno H, Sugie S, et al. Preventive effects of
extract of leaves of ginkgo (Ginkgo biloba) and its component
bilobalide on azoxymethane-induced colonic aberrant crypt foci in rats.
Cancer Lett.
2004;210:159-169.
Ye B, Aponte M, Dai Y, et al. Ginkgo biloba and ovarian
cancer prevention: Epidemiological and biological evidence. Cancer Lett. 2006
Dec 26.
Zeng X, Liu M, Yang Y, et al. Ginkgo biloba for acute
ischaemic stroke. Cochrane
Database Syst Rev. 2005;CD003691.
Note: This information may not
cover all possible claims, uses, actions, precautions, side effects or
interactions. It is not intended as medical advice, and should not be
relied upon as a substitute for consultation with your doctor, who is
familiar with your medical situation.
Revised: 06/26/2007
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