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REF:  http://www.intelihealth.com/IH/ihtIH/WSIHW000/8513/31402.html    

Ginkgo (Ginkgo biloba)

Be aware that the U.S Food and Drug Administration does not strictly regulate herbs and dietary supplements. There is no guarantee of strength, purity or safety of products containing or claiming to contain ginkgo. Decisions to use herbs or supplements should be carefully considered. Individuals using prescription drugs should discuss taking herbs or supplements with a pharmacist or health care professional before starting.

• Evidence
• Unproven Uses
• Potential Dangers
• Interactions
• Dosing
• Summary
• Resources

Evidence    

Scientists have studied ginkgo for the following health problems:

Peripheral vascular disease, claudication

Intermittent claudication is a painful condition caused by clogged arteries in the legs. When people walk, not enough blood gets to muscles, and this can cause cramps or pain. Multiple studies suggest that taking ginkgo by mouth may reduce pain and increase the distance that patients with intermittent claudication can walk without pain. However, conflicting data also exist.

Dementia

Some studies have found that taking ginkgo may slow the progress of Alzheimer's disease or dementia associated with multiple strokes. Many of these studies have had flaws with their design. More studies are needed to determine which patients may benefit the most from ginkgo and what dose of ginkgo provides the best effects.

Cerebral insufficiency

Cerebral insufficiency is a term often used in Europe to describe people with decreased blood flow to the brain caused by clogged arteries. Early evidence suggests that ginkgo may improve short-term memory and concentration and reduce dizziness, headaches and mood disturbances in people with cerebral insufficiency.

Ischemic stroke

Several studies suggest that taking ginkgo by mouth may improve recovery from strokes that result from decreased blood flow to certain areas of the brain. Different studies, however, have produced results that do not agree with each other. Better studies are needed to provide more definitive answers in the future.

Tinnitus (ringing in the ears)

Multiple small, poor-quality studies report reduced ringing in the ears after treatment with ginkgo in people with chronic tinnitus. However, recent well-designed studies found no improvements with ginkgo. It remains unclear if ginkgo is helpful for this condition.

Upper digestive tract malignant tumors

Ginkgo biloba exocarp polysaccharides (GBEP) capsule preparation has been studied for upper digestive tract malignant tumors of middle and late stage with positive results. However, further research is needed before a recommendation can be made.

Acute mountain sickness

Ginkgo biloba has been studied for acute mountain sickness and has not shown definitive benefit over a prescription drug.

Mood and cognition in postmenopausal women

Based on early study of chronic administration, Gincosan appeared to have no beneficial effects on mood, anxiety, or sleepiness in postmenopausal women.

Vertigo

Early study results show that ginkgo may help vertigo. Further research is needed to confirm these results.

Acute hemorrhoidal attacks

In early study, gingko was shown to be effective in the treatment of patients with acute hemorrhoidal attacks. Further research is needed to confirm these results.

Sexual dysfunction due to antidepressant drugs

Based on early study, ginkgo does not seem to help sexual dysfunction due to antidepressant drugs.

Other

Ginkgo has been studied in humans for many other conditions, including acute cochlear deafness, acute hemorrhoidal attack, acute mountain sickness, age-related memory impairment, allergic contact dermatitis, arteritis, asphyxia, asthenic disorders, asthma, circulatory encephalopathy, color vision, coronary heart disease, cognitive performance, depression, decreased sex drive, dizziness, erectile dysfunction, fibromyalgia, glaucoma, macular degeneration, multiple sclerosis, pancreatic cancer, premenstrual syndrome, sexual function, sudden hearing loss, unilateral idiopathic sudden sensorineural hearing loss, vaginal dryness, vascular vestibular disorders, and vertiginous syndrome. In addition, it has been studied in humans to determine if it reduces the side effects associated with chemotherapy. However, there is not enough evidence to make a recommendation for using ginkgo for any of these purposes. Early research suggests that ginkgo may improve memory, but studies have been small with flaws in their designs, and results have disagreed with each other.

Unproven Uses    

Acute cerebral infarction Age-related macular disease Aging Alcohol intoxication Allergies Alzheimer's disease Anti-aging Antibacterial Antidepressant-induced sexual dysfunction Antifungal Antioxidant Antiparasitic Antirheumatic Antitumor Autoimmune disorders Bladder problems Blood clots Bronchial asthma Bronchitis Cancer Cataract Cellulite Chest pain Cocaine dependence Cochleovestibular impairment Colorectal cancer Congestive heart failure Coronary heart disease Cough Deafness Diabetes Diabetic peripheral neuropathy Diarrhea Digestion Eczema Edema Enhancement of female sexual function

Enhancement of learning Enhancement of memory Erectile dysfunction Fatigue Freckle removal Gastric cancer Glaucoma Headache Heart disease Hepatitis B Hypoxia Immunomodulator Insomnia Irregular heart beats Labor induction Mental functioning Mild cognitive impairment Mood disturbances Nerve pain Normal tension glaucoma Oxidative stress Postmenopausal symptoms Postphlebitic syndrome Primary chronic venous insufficiency Raynaud's disease Respiratory (lung) illnesses Scabies Schizophrenia Seasonal affective disorder Seizures Skin irritation Spermicidal Stress Trophic lesions Varicose veins Vestibular organ peripheral lesion syndrome Vitiligo

Potential Dangers      

Allergies

• People with allergies to plants in the Ginkgoaceae family or to urushiols (mango rind, sumac, poison ivy, poison oak) may be more likely to have allergic reactions to ginkgo. One case of a severe, blistering, peeling rash (Stevens-Johnson syndrome) associated with a product that contained ginkgo has been reported. Ginkgo fruit or pulp may cause allergies if applied to the skin. Ginkgo injections have caused severe reactions and are not recommended.

Side Effects

• Few side effects have been reported from ginkgo at recommended doses. The most common complaints include stomach discomfort, nausea, headaches, dizziness or restlessness. Adverse effects such as skin irritation and itching have also occurred but are likely caused by ginkgo allergies. Rarely, heart palpitations (rapid, pounding heartbeats) have been reported. Commonly used doses of Ginkgo biloba do not seem to have any immediate or short-term effects on blood pressure, heart rate, or elecrocardiographic (ECG) variables.
• One serious concern with ginkgo is the possible increased risk of bleeding. There are several cases of people bleeding inside their heads while taking ginkgo, which may occur more frequently in people also taking drugs that affect bleeding, such as aspirin or warfarin. Nosebleeds may also occur with ginkgo use. You may need to stop taking ginkgo before some surgeries because of the risk of bleeding; discuss this with a health care professional.
• It has also been reported that ginkgo may interfere with fertility in both men and women and may cause a decrease in muscle strength. These effects have not been widely studied in humans.
• It is possible that ginkgo may cause seizures, especially in people with a history of seizure disorders or taking other medications that increase the chance of having a seizure. Ginkgo may affect the outcome of electroconsulvie therapy. Adverse effects on the eyes have been reported.

Pregnancy And Breast-Feeding

Interactions    

• Ginkgo may increase the risk of bleeding when used with anticoagulants (blood thinners) or antiplatelet drugs. Examples include warfarin (Coumadin), heparin and clopidogrel (Plavix). Some pain relievers may also increase the risk of bleeding if used with ginkgo. Examples include aspirin, ibuprofen (Motrin, Advil) and naproxen (Naprosyn, Aleve, Anaprox). It has been suggested that ginkgo may increase the risk of bleeding if taken with acetaminophen (Tylenol), pentoxifylline (Trental) and vitamin E, although there is not a lot of information in this area.
• Individuals with a history of diabetes should be careful when taking ginkgo. In theory, ginkgo may lower blood sugar levels. Caution is advised if you are also taking drugs that may lower blood sugar levels. Patients taking oral drugs for diabetes or using insulin should be monitored closely by a health care professional while using ginkgo. Dosing adjustments may be necessary. It is possible that ginkgo may cause seizures, especially in people with a history of seizure disorders. You should avoid taking other drugs that increase the risk of seizures if you are taking ginkgo.
• Many other possible drug interactions could, in theory, lead to adverse effects. Examples include increased side effects if used with antidepressants, such as fluoxetine (Prozac); cholinesterase inhibitors, such as donepezil (Aricept); or drugs used to treat high blood pressure. Possible beneficial drug interactions that may, in theory, occur with the use of ginkgo are less toxicity associated with chemotherapy, improvements in erectile function when used with papaverine, and fewer adverse effects when used with antipsychotic drugs. Many of these drug interactions have not been widely studied in humans.
• Gingko may alter the way the liver breaks down certain drugs

Interactions With Herbs And Dietary Supplements

• Very few interactions between ginkgo and herbs or supplements have been reported, but some are considered possible. For example, side effects such as muscle stiffness, rapid heartbeats, fever, restlessness and sweating may occur if gingko is used with St. John's wort. In theory, ginkgo may increase the risk of bleeding when also taken with other products that are believed to increase the risk of bleeding, such as garlic (Allium sativum). Vitamin E and ginkgo taken together may also increase the risk of bleeding. It is also possible that ginkgo may lower blood sugar levels. People using other herbs or supplements that may alter blood sugar levels, such as bitter melon (Momordica charantia), should be monitored closely by a health care professional while using ginkgo. Dosing adjustments may be necessary.
• Although not widely studied, ginkgo may lower blood pressure levels and should be used cautiously with other herbs or supplements that may affect blood pressure levels, such as hawthorn (Crataegus oxyacantha). Gingko may alter the way the liver breaks down herbs and supplements.

Dosing

Some natural medicine experts recommend ginkgo products that contain 24 percent flavoglycosides and 6 percent terpenes. Beneficial effects may not be seen for four to six weeks.

• Capsules/tablets: Doses of 80 to 240 milligrams daily of a 50:1 standardized leaf extract, divided into two or three doses, have been taken by mouth. There is evidence that 240 milligrams daily is most beneficial for intermittent claudication. For patients diagnosed with unilateral idiopathic sudden sensorineural hearing loss, an oral dose of 120 milligrams EGb 761 twice daily has been used.
• Liquid/fluid: Doses of three to six milliliters daily of an extract concentrated to 40 milligrams per milliliter, divided into two or three doses, have been taken by mouth. There is evidence that six milliliters daily is most effective for intermittent claudication.
• Tea: A preparation of 40 milligrams of ginkgo extract in a teabag has been used, but there are no reliable data to recommend a specific tea dose.

Children (Younger Than 18): The dosing and safety of ginkgo have not been studied thoroughly in children, and use of this herb is not recommended. Seizures have been reported in children.

Summary    

Although ginkgo has been suggested for many conditions, it has been most studied as a treatment for peripheral vascular disease, dementia and cerebrovascular insufficiency. Ginkgo has not been proven for any other health condition. It should be avoided in pregnant or breast-feeding women and in children. If you are considering using ginkgo but have diabetes or seizures or are prone to bleeding disorders, you should discuss this with a health care professional. Beneficial effects may not be seen until ginkgo is used for four to six weeks. Consult a health care professional immediately if you experience side effects.

The information in this monograph was prepared by the professional staff at Natural Standard, based on thorough systematic review of scientific evidence. The material was reviewed by the Faculty of the Harvard Medical School with final editing approved by Natural Standard.

Resources      

Selected Scientific Studies: Ginkgo

Some of the more recent studies are listed below:

Last updated July 11, 2005