Common name: Maidenhair tree
Botanical name: Ginkgo biloba
© Steven Foster
Parts used and where grown
Ginkgo biloba is the world’s oldest living species of tree. Individual trees
live as long as 1,000 years. Ginkgo grows most predominantly in the southern and eastern
United States, southern France, China, and Korea. The leaves of the tree are used in modern
Ginkgo biloba has
been used in connection with the following conditions (refer to the
individual health concern for complete information):
Historical or traditional use (may
or may not be supported by scientific studies)
Medicinal use of ginkgo can be traced back almost 5,000 years in Chinese herbal medicine.
The nuts of the tree were most commonly recommended and used to treat respiratory tract
ailments. The use of the leaves is a modern development originating in Europe.
The medical benefits of Ginkgo biloba extract are attributed primarily to two
groups of active constituents: the ginkgo flavone glycosides and the terpene lactones. Ginkgo
flavone glycosides, which typically make up approximately 24% of the extract, are primarily
responsible for ginkgo’s antioxidant
activity and may mildly inhibit platelet aggregation (stickiness). These two actions may help
ginkgo prevent circulatory diseases, such as
atherosclerosis, and support the brain and central nervous system.1 In addition
to the cardiovascular system, ginkgo’s antioxidant action may also extend to the brain
and retina of the eye.2 Preliminary trials have suggested potential benefit for
people with macular degeneration3
and diabetic retinopathy.4 The
terpene lactones found in ginkgo extracts, known as ginkgolides and bilobalide, typically make
up approximately 6% of the extract. They are associated with increasing circulation to the
brain and other parts of the body and may exert a protective action on nerve
cells.5 ginkgo regulates the tone and elasticity of blood vessels,6
making circulation more efficient.7
Ginkgo is also well-known for its effect on memory and thinking (cognitive function). It
may enhance cognitive performance in healthy older adults,8 in people with age-related cognitive decline, and in people with Alzheimer’s disease.
How much is usually taken?
Most clinical trials have used between 120 and 240 mg of ginkgo (standardized to contain 6%
terpene lactones and 24% flavone glycosides) per day, generally divided into two or three
portions.9 The higher amount (240 mg per day) has been used in some people with
mild-to-moderate Alzheimer’s disease, age-related cognitive decline, intermittent claudication, and resistant depression. Ginkgo may need to be taken for eight to
twelve weeks before desired actions such as cognitive improvement are noticed. Although
nonstandardized Ginkgo biloba leaf and tinctures are available, there is no
well-established amount or use for these forms.
Are there any side effects or interactions?
Excessive bleeding has been reported in a few individuals taking ginkgo,10
11 although a cause/effect relationship was not proven. In addition, two elderly
individuals with well-controlled epilepsy developed recurrent seizures within two weeks after
starting ginkgo.12 Mild headaches lasting for a day or two and mild upset stomach
have been reported in a small number of people using ginkgo.
Ginkgo leaves are known to contain a group of potentially toxic constituents known as
alkylphenols. To reduce the potential for adverse effects, the German Commission E Monograph
requires that ginkgo products for human consumption contain less than 5 parts per million of
One small clinical trial found that ginkgo supplementation for three months increased
secretion of insulin by the pancreas, but did
not affect blood glucose levels, in healthy young adults.14 These results suggest
that the participants may have developed an insensitivity to insulin, a potential concern
because insulin insensitivity may be a precursor to type 2 diabetes. However, this trial does not prove that
ginkgo causes insulin insensitivity, nor does it prove that long-term ginkgo supplementation
increases the risk for any disease. In addition, the results of this trial are not consistent
with other research on ginkgo. Larger and more rigorously designed clinical trials of ginkgo
supplementation have found no significant adverse effects after as many as 12 months of
People should seek an accurate medical diagnosis prior to self-prescribing ginkgo. This is
especially important for the elderly, whose circulatory conditions can involve serious
disease, and for people scheduled for surgery, as ginkgo may affect bleeding time.
Are there any drug
Certain medicines may interact with Ginkgo biloba. Refer to drug interactions for a list of those medicines.
1. Drieu K. Preparation and definition of Ginkgo biloba extract.
In: Rokan (Ginkgo biloba): Recent Results in Pharmacology and Clinic. Fünfgeld
EW, ed. Berlin: Springer-Verlag, 32–6.
2. Ferrandini C, Droy-Lefaix MT, Christen Y, eds. Ginkgo biloba
Extract (EGb 761) as a Free Radical Scavenger. Paris: Elsevier, 1993.
3. Lebuisson DA, Leroy L, Rigal G. Treatment of senile macular
degeneration with Ginkgo biloba extract. A preliminary double-blind, drug versus
placebo study. Presse Med 1986;15:1556–8 [in French].
4. Lanthony P, Cosson JP. Evolution of color vision in diabetic
retinopathy treated by extract of Ginkgo biloba. J Fr Ophthalmol 1988;11:671–4
5. Krieglstein J. Neuroprotective properties of Ginkgo
biloba—constituents. Zeitschrift Phytother 1994;15:92–6.
6. Clostre F. From the body to the cell membranes: the different levels
of pharmacological action of Ginkgo biloba extract. In: Rokan (Ginkgo biloba):
Recent Results in Pharmacology and Clinic.Fünfgeld EW, ed. Berlin: Springer-Verlag,
7. Jung F, Mrowietz C, Kiesewetter H, Wenzel E. Effect of Ginkgo
biloba on fluidity of blood and peripheral microcirculation in volunteers.
8. Mix JA, Crews WD. An examination of the efficacy of Ginkgo biloba
extract EGb761 on the neuropsychologic functioning of cognitively intact older adults. J
Altern Complement Med 2000;6:219–29.
9. Blumenthal M, Busse WR, Goldberg A, et al, eds. The Complete
Commission E Monographs: Therapeutic Guide to Herbal Medicines. Boston, MA: Integrative
Medicine Communications, 1998, 136–8.
10. Matthews MK Jr. Association of Ginkgo biloba with intracerebral
hemorrhage. Neurology 1998;50:1933–4 [letter].
11. Rosenblatt M, Mindel J. Spontaneous hyphema associated with ingestion
of Ginkgo biloba extract. N Engl J Med 1997;336:1108 [letter].
12. Granger AS. Ginkgo biloba precipitating epileptic seizures. Age
13. Siegers CP. Cytotoxicity of alkylphenols from Ginkgo biloba.
14. Kudolo GB. The effect of 3-month ingestion of Ginkgo biloba
extract on pancreatic ß-cell function in response to glucose loading in normal
glucose-tolerant individuals. J Clin Pharmacol 2000;40:647–54.
15. 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;278:1327–32.