Traceable back 300 million years, the ginkgo is the oldest surviving species of tree. Although it died out in Europe during the Ice Age, ginkgo survived in China, Japan, and other parts of East Asia. It has been cultivated extensively for both ceremonial and medical purposes, and some particularly revered trees have been lovingly tended for more than 1,000 years.

In traditional Chinese herbology, tea made from ginkgo seeds has been used for numerous problems, most particularly asthma and other respiratory illnesses. The leaf was not used. But in the 1950s, German researchers started to investigate the medical possibilities of ginkgo leaf extracts rather than remedies using the seeds. Thus, modern ginkgo preparations are not the same as the traditional Chinese herb, and the comparisons often drawn are incorrect.

Fairly good evidence indicates that ginkgo is effective for Alzheimer's diseaseand other severe forms of memory and mental function decline; when used for this purpose, it appears to be as effective as standard drugs.1,2-7,48,50,109,149,163,171

Inconsistent evidence hints that ginkgo might be helpful for enhancing memoryand mental function in seniors without severe memory loss as well.8-14,73,103,110,111,112 Weak evidence hints that ginkgo (alone or in combination with ginseng or vinpocetine) may be helpful for enhancing memory or alertness in younger people.15-18,90,113 Combining phosphatidylserine(another substance used to enhance mental function) along with ginkgo might increase its efficacy.153

In addition, ginkgo may be effective for the treatment of restricted circulation in the legs due to hardening of the arteries known as intermittent claudication.19-22,114

One substantial, well-designed double-blind, placebo-controlled study found evidence that ginkgo extract taken at a dose of 480 mg or 240 mg daily may be helpful for anxiety.148

Weak and, in some cases inconsistent, evidence from preliminary double-blind trials hints that ginkgo might be helpful for glaucoma,72macular degeneration,68,71conjunctivitis,168PMS,29Raynaud’s disease,69sudden hearing loss,32,33vertigo,31 and vitiligo.115

Although study results conflict, on balance the evidence suggests that ginkgo is not helpful for tinnitus(ringing in the ear).34-39,96,116

Three small, double-blind trials enrolling a total of about 100 people found preliminary evidence that use of the herb Ginkgo biloba can help prevent altitude sickness.30,102,159However, a large scale, double-blind study enrolling 614 people, failed to find benefit.117(The drug acetazolamide, however, did provide significant benefits compared to placebo.) A similarly designed smaller study enrolling 57 people also failed to find ginkgo effective.160 Overall, the balance of evidence suggests that ginkgo is not effective for this purpose.

Numerous case reports and uncontrolled studies raised hopes that ginkgo might be an effective treatment for sexual dysfunction in men or women, particularly in those cases related to certain antidepressant medications.23-27 However, the results of a number of double-blind studies (see Why Does this Database Rely on Double-blind Studies?) indicate that ginkgo is no more effective than placebo, whether or not subjects are taking antidepressants.70,129,161

One small study failed to find ginkgo helpful for the treatment of cocaine dependence.118 Two studies failed to find ginkgo helpful in multiple sclerosis.128,154In addition, another study found ginkgo biloba did not improve cognitive function on neuropsychological test scores compared to placebo in a randomized trial of 121 patients with multiple sclerosis.172This was also supported in a review of 4 studies. However, ginkgo was associated with improving fatigue symptoms after 4 weeks when compared to placebo.174

Chinese research suggests that ginkgo might enhance the effects of drugs used for schizophrenia (both phenothiazines as well as atypical antipsychoticdrugs).28,93 Antipsychotic drugs can cause a neurological condition called tardive dyskinesia, which involves troubling, uncontrollable body movements.170 One randomized study found that ginkgo (240 mg/day for 12 weeks) was more helpful than placebo in reducing tardive dyskinesia symptoms in people with schizophrenia.

An open studyevaluated combination therapy with ginkgo extract and the chemotherapy drug 5FU for the treatment of pancreatic cancer, on the theory that ginkgo might enhance blood flow to the tumor and thereby help 5FU penetrate better.40The results were promising, but much better research must be performed before ginkgo can be recommended for this use. Similarly inadequate evidence hints at benefits in dyslexia.156

Ginkgo has also been proposed as a treatment for depression and diabetic retinopathy, but there is little evidence that it is effective for these conditions.

Note: There are some theoretical safety concerns regarding ginkgo anddiabetes. SeeSafety Issues for more information.