Ginkgo

Ginkgo biloba

Family: Ginkgoaceae Part used: Leaves, seeds (ginnan)

Key Compounds

• Ginkgolide A
• Ginkgolide B
• Ginkgolide C
• Ginkgolide J
• Bilobalide
• Quercetin-3-rutinoside
• Kaempferol-3-rutinoside
• Isorhamnetin glycosides
• Amentoflavone
• Bilobetin
• Ginkgetin

Traditional Use

• Traditional Chinese medicine — used for over 1,000 years for respiratory conditions, bladder function, and as a kitchen ingredient (ginnan seeds in congee and grilled dishes)
• European pharmaceutical medicine — EGb 761 standardised extract developed and approved as a pharmaceutical in Germany for peripheral vascular disease and dementia; licensed as a prescription drug in France and Germany since the 1980s
• Cognitive and circulatory research — multiple RCTs on age-related cognitive decline and peripheral circulation; largest clinical trial (GEM Study, 2008) showed no prevention of Alzheimer's in healthy elderly adults; evidence supports modest improvement in established vascular dementia
• Intermittent claudication — clinical evidence supports improvement in walking distance in peripheral arterial disease; recommended in European clinical guidelines
• Culinary use in Japan — ginnan (銀杏) seeds roasted and eaten as bar snacks, cooked in chawanmushi (egg custard), grilled on skewers at festivals; one of the most distinctive flavours in Japanese autumn cuisine

Ginkgo biloba is the only surviving species in the entire division Ginkgophyta.

Not the only species in the genus. The only species in the division — a taxonomic rank above class, one level below kingdom. The entire division, which once included dozens of genera distributed across the globe, is now a single species in a single genus in a single family. The extinction is comprehensive. Only ginkgo is left.

The tree looks ancient. Fan-shaped leaves, two-lobed (which is what biloba means), attached to short spurs on heavy branches. Specimens in Chinese and Japanese temple grounds are documented at 1,200–1,500 years old. The species is far older: fossils are found dating to 270 million years ago, before flowering plants existed, before the continents had separated into their current positions. It survived whatever killed the dinosaurs. It survived the ice ages by retreating to a small area of central China.

It is still here.

Meet the plant

A large deciduous tree, reaching 25–35 metres in cultivation, taller in old specimens. The leaves are fan-shaped with a slight central notch. In autumn they turn a uniform, saturated yellow. Male and female trees are separate. Female trees produce seeds enclosed in a fleshy, strongly malodorous outer layer — the smell comes from butyric acid, the same compound responsible for the smell of rancid butter. The inner kernel (ginnan) is the edible part. Sellers remove the outer layer before bringing the seeds to market, which is a reasonable decision.

The ginkgolides — the primary active compounds — are diterpenoid cage structures found in no other plant species on earth. This is not a rhetorical point about uniqueness. The compounds are chemically distinctive enough that their discovery represented a new structural class. They are ginkgo’s alone.

A Living Fossil: 270 Million Years

Ginkgo fossils appear in rocks from the Permian period. The Permian ended approximately 252 million years ago with the largest mass extinction in Earth’s history — the one that killed roughly 90% of marine species and 70% of terrestrial species. Ginkgo survived it. The Triassic, Jurassic, and Cretaceous periods came and went. Ginkgo was present throughout all of them. Multiple species of ginkgo were present — Ginkgo adiantoides, Ginkgo digitata, others — spread across both hemispheres when the continents were still connected.

They disappeared one by one. The reasons are not fully understood. By the late Miocene the genus had contracted to Asia. By the Pleistocene, to a small area of central China. Sometime after the last ice age, humans — specifically Chinese Buddhist monks — began cultivating ginkgo near temples. The tree was considered sacred. It was planted. It spread. The species that would otherwise have followed its relatives into extinction survived because humans found it useful and beautiful.

This is not unusual. Many of the plants in cultivation today exist because humans selected and propagated them. What is unusual is the timeline. The relationship between ginkgo and human cultivation may have saved a 270-million-year lineage from extinction by a narrow margin.

The Hiroshima trees

Six ginkgo trees in Hiroshima survived the atomic bombing on August 6, 1945.

The trees were within 1–2 kilometres of the hypocentre. The buildings around them were destroyed. The trees were badly damaged. They were not killed. The following spring — spring 1946 — they budded again.

These are not symbolic trees or composite stories. They are specific, documented, living trees. Several are still alive today. Plaques at some sites describe the bombing date and the trees’ survival. The hibaku jumoku (被爆樹木, bomb-surviving trees) are recorded and mapped. Ginkgo is disproportionately represented among them — more ginkgo trees in Hiroshima survived than any other species.

The tree’s exceptional stress tolerance is likely connected to the same antioxidant mechanisms that attract interest in its medicinal applications. 270 million years of surviving catastrophic events produces durable chemistry.

The chemistry

The pharmacologically active compounds fall into two structural categories.

Ginkgolides are diterpenoid cage structures — complex molecules with a structural cage of interlocking rings unlike anything else in the plant kingdom. Ginkgolide B is the most studied; it inhibits platelet-activating factor (PAF), a compound involved in blood clotting, inflammation, and bronchospasm. This PAF-antagonism mechanism explains the circulatory effects.

Bilobalide is a sesquiterpene lactone with demonstrated neuroprotective activity in laboratory models. It protects neurons from ischemic damage (damage from reduced blood flow) and has shown activity against some neurotoxic compounds in cell studies.

Flavonoid glycosides — primarily quercetin and kaempferol glycosides — provide antioxidant activity. The flavonoids in ginkgo extract are similar to those found in other plants; the ginkgolides and bilobalide are unique.

EGb 761 — the standardised extract developed by Dr. Willmar Schwabe GmbH in Germany in the 1960s — is standardised to 24% flavonoid glycosides and 6% terpene lactones. Almost all clinical trials on ginkgo used this specific extract. When you read about ginkgo research, you are reading about EGb 761.

What people actually do with it

Standardised extract (clinical form): EGb 761 or an extract standardised to 24% flavonoid glycosides and 6% terpene lactones. Typical dose: 120–240 mg daily, divided into two doses. Take with food. Effects, when they occur, take 4–8 weeks to manifest. This is the form with the clinical evidence base — not tea, not fresh leaves.

Duration: Ginkgo is used long-term. Short trials (under 4 weeks) tend to show minimal effects. Most clinical studies used 12–24 week protocols.

Note on the seeds: Ginnan seeds are a food, not a supplement. They are not interchangeable with leaf extract. The seeds contain ginkgotoxin (4’-O-methylpyridoxine), which is toxic at high doses — particularly in children. Eating ginnan in normal culinary quantities (a few seeds in chawanmushi or 10–20 roasted at a festival) is safe for adults. Consuming large quantities is not.

Could you grow this yourself?

Yes. Ginkgo is an exceptionally hardy tree that grows throughout Japan.

The tree tolerates a wide range of soil types, urban pollution, and temperature variation. It grows from Hokkaido to Okinawa and is planted extensively in Japanese streets and parks. Seed germination is reliable; trees from seed require 20+ years before fruiting, but ginkgo is a long-lived tree and this is not unusual in that context.

For medicinal leaf harvest: collect leaves in late summer before they turn yellow. The flavonoid and terpene content is highest before senescence begins. Dry at low heat and store. The pharmaceutical-grade extract cannot be replicated at home — it requires industrial extraction and standardisation — but the leaves contain the active compounds.

For the male tree: male trees do not produce seeds and do not produce the malodorous fleshy outer seed coat. Male trees are preferred for urban planting for this reason. If you want seeds (ginnan), you need a female tree.

Ginkgo (イチョウ) in Japan

Japan’s relationship with ginkgo is layered and runs deep.

The ginkgo is the official symbol of Tokyo Metropolis. The Metropolitan Government’s emblem uses the fan-shaped leaf. The same leaf appears on the emblems of the Metropolitan Police, Waseda University, and several other major Tokyo institutions. The tree itself lines major avenues — the Jingu Gaien in Minato ward features approximately 150 ginkgo trees, which turn yellow in late November and create what is arguably the most photographed autumn street in the city. The Jingu Gaien ginkgo illumination is an annual event.

This is not purely aesthetic. Japan has one of the oldest relationships between human culture and ginkgo trees outside China. Buddhist temples and Shinto shrines throughout Japan have ginkgo trees that were planted 800–1,200 years ago. The tree’s association with sacred sites and longevity predates the European discovery of its medicinal properties by centuries.

The edible seed — ginnan (銀杏) — is woven into Japanese autumn cuisine. Grilled and salted ginnan appear on yakitori menus and at festival stalls in October and November. They go into chawanmushi (savoury steamed egg custard), into dobin mushi (a broth served in a clay pot), into autumn rice dishes. The flavour — mild, waxy, slightly bitter — is specific and seasonal. It does not appear at other times of year.

The leaf extract arrived separately, through Western pharmacological research. EGb 761 was developed in Germany, not Japan. Japanese consumers encounter standardised ginkgo extract primarily as an imported supplement (イチョウ葉エキス, ichō ha ekisu) rather than through the traditional medical system. Ginkgo does not appear as a classical kampo ingredient — the leaf was not historically used in kampo practice, which used the seeds for urinary and respiratory conditions.

The tree and the supplement exist as parallel cultural facts, pointing at the same species.

Things you’re probably wondering

What does the research actually show? The GEM Study (2008), a large NIH-funded trial following 3,000 elderly adults for 6 years, found that ginkgo did not prevent Alzheimer’s disease in healthy people. Smaller studies and meta-analyses show modest benefit for existing vascular dementia and intermittent claudication (leg pain from poor circulation). The distinction: ginkgo appears not to prevent decline in healthy people, but may modestly improve symptoms in those with established vascular cognitive impairment.

What is EGb 761? The standardised extract developed by Willmar Schwabe GmbH in Germany, standardised to 24% flavonoid glycosides and 6% terpene lactones. Almost all clinical research used this extract. It is licensed as a pharmaceutical in Germany and France.

Did ginkgo trees really survive Hiroshima? Yes. Six specific trees within 1–2 km of the hypocentre survived the 1945 atomic bombing and budded again in 1946. Several are still living today. Documented and mapped as hibaku jumoku (bomb-surviving trees).

What are ginnan? The edible inner seed kernels of female ginkgo trees. Eaten grilled, in chawanmushi, and in autumn rice dishes in Japan. Should not be consumed in large quantities due to ginkgotoxin content — a few at a time is fine.

Is ginkgo Tokyo’s symbol? Yes. The ginkgo leaf (イチョウの葉) has been the official emblem of Tokyo Metropolis since 1989. The Jingu Gaien avenue ginkgo turning yellow in late November is one of the defining autumn scenes in the city.

Botanical details

The full compound list

See Also

• Brahmi — the other major cognitive herb; different mechanism (dendritic growth vs. circulation)
• Lion’s Mane — NGF stimulation for neural growth; complements ginkgo’s circulatory mechanism
• Eleuthero — adaptogen with overlapping cognitive and circulatory applications

References

• DeFeudis, F.V. (1991). Ginkgo biloba Extract (EGb 761): Pharmacological Activities and Clinical Applications. Elsevier.
• DeKosky, S.T. et al. (2008). Ginkgo biloba for prevention of dementia: A randomized controlled trial. JAMA, 300(19), 2253–2262. (GEM Study)
• Weinmann, S. et al. (2010). Effects of Ginkgo biloba in dementia: Systematic review and meta-analysis. BMC Geriatrics, 10, 14.
• Birks, J. & Grimley Evans, J. (2009). Ginkgo biloba for cognitive impairment and dementia. Cochrane Database of Systematic Reviews, 1.
• Sierpina, V.S. et al. (2003). Ginkgo biloba. American Family Physician, 68(5), 923–926.