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Ginkgo biloba is an herbal dietary supplement made from the leaves of the tree Gingko biloba.
Ginkgo biloba, sometimes called bai guo, has been used in Traditional Chinese Medicine (TCM) for about 5,000 years to treat memory loss, mood, nerve, circulatory and many other health problems. Ginkgo biloba often is combined with ginseng to boost memory, improve the quality of life, and increase a sense of well being. The effectiveness of some TCM uses of gingko, such as relieving pain caused by clogged arteries in the leg (claudication), treating Alzheimer’s disease, and improving blood flow to the brain have been evaluated in well-designed studies and are generally accepted by practitioners of conventional medicine. Many other TCM uses of gingko biloba are currently being investigated.
Gingko biloba is the last existing member of an ancient family of trees. The fossil record shows that gingko trees existed 200 million years ago. Gingko biloba is native to China, Japan, and Korea. The tree was introduced to North America in the 1700s. Ginkgo trees grow to a height of 65–115 ft (20–35 m). They are extremely resistant to disease and insect damage and can live for several hundred years. Female trees produce bad-smelling fruit-like bodies the size of an apricot that contains seeds. Herbal practitioners sometimes use the seeds in treatment. The much cleaner male ginkgo is a popular tree for urban landscaping
The fan-shaped leaves of the ginkgo are used for medicinal purposes. About twenty different compounds have been identified in ginkgo leaves, but the medically active ingredients appear to be flavenoids and terpe-noids. Flavenoids are antioxidants that help lower the level of free radicals in the body. Terpenoids are thought
to protect nerves from damage, reduce inflammation, and decrease blood clotting
In the United States, Gingko biloba is cultivated and the leaves are harvested and dried, then often used to make a standardized extract that contains 24–25% flavenoids and 6% terpenoids. U. S. law does not require the standardization of dietary supplements, so consumers should read all labels carefully. Ginkgo biloba is often sold as capsules and tablets. Dry and liquid ginkgo extract is added to other herbal remedies as well as teas, energy or health bars, and similar products. An injectable form of ginkgo biloba extract that was available in Europe has been withdrawn from the market because of adverse side effects. Most well-designed studies have been done using a total of 80– 240 mg of 50:1 standardized extract divided into 2 or 3 doses daily and taken by mouth.
Regulation of ginkgo biloba sales
Ginkgo biloba is one of the top selling herbal remedies in the United States and is even more popular in Europe. Under the 1994 Dietary Supplement Health and Education Act (DSHEA), the sale of ginkgo biloba is regulated by the U.S. Food and Drug Administration (FDA) as a dietary supplement. At the time the act was passed, legislators felt because many dietary supplements such as ginkgo biloba come from natural sources and have been used for hundreds of years by practitioners of complementary and alternative medicine (CAM), supplements did not need to be regulated as rigorously as prescription and over-the-counter drugs used in conventional medicine.
Gingko biloba is one of the most promising traditional herbs investigated by Western medicine. The National Center for Complementary and Alternative Medicine (NCCAM), a government organization within the National Institutes of Health, is sponsoring clinical trials to determine safety and effectiveness of gingko biloba as a treatment for more than a dozen diseases and disorders. Individuals interested in participating in a clinical trial at no charge can find a list of open trials at <//www.clinicaltrials.gov>.
Some health claims for gingko biloba have already been evaluated in large, well-controlled studies that satisfy the proof of safety and effectiveness demanded by conventional medicine. There is good evidence that gingko biloba can cause short-term improvement in mental function in people with Alzheimer’s disease. In a well-designed study, ginkgo biloba was as effective as the prescription drug done-pezil (Aricept) in slowing the development of dementia in people with mild to moderate Alzheimer’s. Ginkgo biloba has also been shown to be effective in improving blood flow to the brain and in treating certain other dementias. The effect of ginkgo biloba on memory in healthy young adults and in people with age-related memory impairment is inconsistent, but strong enough to continue to study the effects of the herb in these populations.
In other rigorous studies, ginkgo biloba has improved symptoms of claudication. Claudication is leg pain that occurs during walking when insufficient oxygen reaches the leg muscles. It is usually caused by blocked arteries in the leg. Ginkgo biloba’s ability to reduce blood clotting (“thin the blood”) is thought to account for improving symptoms in people with claudication. However, exercise and prescription medication were more effective in reducing leg pain due to claudication than ginkgo biloba alone. Ginkgo biloba has also been used, especially in Europe, to treat Ray-naud’s disease. Raynaud’s disease causes the extremities of the body to feel cold in response to stress or cool temperatures. During an attack of Raynaud’s disease, the blood vessels to the affected area narrow and blood flow is reduced.
Several health claims for ginkgo biloba center on treating disorders of the eye, including glaucoma, age-related macular degeneration, and type 2 diabetes-related retinopathy. Ginkgo appears to increase blood flow to the eye, but additional studies need to be done to evaluate its effectiveness in helping to treat these disorders.
The terpenoids in ginkgo biloba are thought to help prevent nerve damage. Because of this, ginkgo has been suggested as a treatment for tinnitus (ringing of the ears), multiple sclerosis, cochlear deafness, and Huntingdon’s disease. Results of studies so far are inconsistent, and additional research is needed to determine the usefulness of ginkgo in nerve disorders.
Some researchers have suggested that ginkgo bilobais useful in treating depression, seasonal affective disorder, premenstrual syndrome, altitude sickness, vertigo (dizziness), premenstrual syndrome (PMS), gastric cancer, side effects of anti-cancer drugs, and pulmonary interstitial fibrosis, as well as generally improving quality of live and sense of well being. Further studies need to be done to evaluate these health claims.
Ginkgo biloba seeds contain toxins that can cause vomiting, seizures, loss of consciousness, and death, especially in young children. Ginkgo biloba seeds are not safe and should be avoided.
Extracts of the leaf of Gingko biloba are generally safe and cause few side effects when taken at recommended doses for up to six months. People who are planning to have surgery should stop taking ginkgo biloba at least two days before their operation because of the risk of increased bleeding. The safety of gingko biloba in children and pregnant and breastfeeding women is still being studied.
Ginkgo biloba has blood-thinning properties and is likely to increase the blood-thinning and anticoagulant effects of medicines such as warfarin (Coumadin), clopidogrel (Plavix), aspirin, and nonsteroidal anti-inflammatory drugs (e.g. Advil, Motrin). Individuals taking these drugs should not begin taking ginkgo biloba without consulting their health care provider.
Ginkgo biloba may also interact with mono-amine-oxidase (MAO) inhibitors used to treat certain kinds of depression and mental illness. Examples of MAOs include isocarboxazid (Marplan), phenelzine (Nardil) and tranylcypromine (Parnate). Individuals taking MAOs along with ginkgo biloba may experience increased effects from the MAO.
Some reports suggest that ginkgo biloba lowers blood sugar levels. Individuals who are taking insulin or other medications that also lower blood sugar, and those with type 2 diabetes, should consult their health care provider before starting to take ginkgo biloba.
Serious side effects of ginkgo biloba are rare. The most common mild side effects are headache, dizziness, nausea, diarrhea, increased restlessness, and racing heart. Increased bleeding may occur. Allergic reactions to gingko are possible, but uncommon. In severe rare cases, the skin blisters and sloughs off, a condition called Stevens-Johnson syndrome. People who are allergic to sumac, mango rind, cashews, poison oak, and poison ivy are at slightly higher risk to have an allergic reaction to ginkgo biloba.
Parents should be aware that the safe dose of many herbal supplements has not been establsihed for children. Accidental overdose may occur if children are give adult herbal supplements.
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