Ginkgo

Ginkgo (Ginkgo biloba) is a deciduous tree so ancient that it is commonly called a "living fossil": it is the last remaining species of a primitive family of plants. It is native to southern China.

Type

Plant

Botanical name

Ginkgo biloba

Other names

maidenhair tree, fossil tree, Japanese silver apricot

Plant

Ginkgo has two-lobed, somewhat leathery, fan-shaped leaves with almost parallel veins, which turn bright yellow in autumn. The name maidenhair tree refers to their likeness to the leaflets of maidenhair fern. Trees are either male or female; nurseries usually sell male trees, because the seeds of female trees are messy and smell foul when they fall and split open.

The genus name is a misrendering of the Japanese for "silver apricot", used in 17th-century Japan, and biloba means two-lobed, after the leaves.

Uses

Ginkgo is planted as a lawn, street or shade tree. It has a long history of use in Chinese medicine for cough, diarrhoea and other conditions; today the leaf, usually as an extract, is the most common form, including in dietary supplements. Ginkgo has not been shown to be effective for any of the conditions it has been studied for.

Powdered ginkgo leaf is traditionally used to relieve heavy legs and cold hands and feet with minor circulation problems; this rests on long experience, not on clinical trials. Medicines made with ginkgo leaf extract are used for age-related decline in mental abilities in adults with mild dementia. Health Canada lets licensed leaf-extract products for adults claim help with thinking, memory and circulation in the limbs, but not for people taking blood thinners. The US National Center for Complementary and Integrative Health (NCCIH) finds it uncertain whether ginkgo affects thinking in healthy people.

The World Health Organization's 1999 monograph on ginkgo leaf lists no uses from pharmacopoeias or traditional systems of medicine. It treats as supported by clinical data the use of standardised extracts for mild to moderate dementia symptoms, such as poor memory and concentration, and for tinnitus and vertigo. Such extracts are also used to lengthen pain-free walking in people with poor leg circulation. Bronchitis, arthritis and inducing labour appear only as folk uses without experimental or clinical support. This 1999 view of the clinical evidence is more favourable than that of NCCIH.

Safety

For most adults, ginkgo leaf extracts are likely to be safe in moderate amounts. Fresh ginkgo seeds, however, are toxic, and serious side effects have occurred after eating roasted seeds or the crude plant. Ginkgo may increase the risk of bleeding in people who take blood thinners such as warfarin, and it may be unsafe in pregnancy.

Products containing it

• Ginkolin Forte capsules (D 230)