Who Documented Ginkgo, and How a Temple Tree Became a Leaf Extract Story

Ginkgo was kept in Chinese mountain monasteries until about 1100 AD, and its leaf extract later reached supplement shelves in Europe and the United States. Two large dementia trials on that extract found no reduction in dementia. This history covers the tree, the seeds, the extract and the trial numbers, each tied to its source.

The history of ginkgo starts in mountain monasteries in China, not in a laboratory. Ginkgo biloba is the last surviving species of its lineage, and Buddhist monks kept it growing in those monasteries until it spread out of the mountains around 1100 AD, according to the [University of California Museum of Paleontology](https://ucmp.berkeley.edu/seedplants/ginkgoales/ginkgofr.html). The leaf extract is a modern product. The trials of that extract are where the evidence sits, and the two large dementia trials did not show a benefit. ## Why is ginkgo called a living fossil? Ginkgo's lineage goes back to the Lower Jurassic, about 190 million years ago. The genus peaked in the Cretaceous with five or six Northern Hemisphere species. By the Paleocene it was down to one polymorphic species whose leaves look almost identical to those of modern ginkgo. [NCCIH](https://www.nccih.nih.gov/health/ginkgo) uses the same term and calls ginkgo the last remaining species of a primitive family of plants. Here is the part that surprised people. No ginkgo fossils from the Pleistocene are known, so researchers assumed the genus had died out. *Ginkgo biloba* had survived in China all along. ## How did ginkgo reach Europe? The tree then spread through temperate Asia, and UCMP says it was first planted in Europe in the early 1700s and in America later that century. [Harvard's Widener Library](https://archive.blogs.harvard.edu/preserving/2016/03/30/engelbert-kaempfers-17th-century-sojourn-to-japan/) credits Engelbert Kaempfer, a physician who spent two years at the Dutch trading post at Nagasaki, as the first Westerner to bring ginkgo seeds back to Europe. ## What did Chinese medicine use ginkgo for? Seeds were the part most commonly used. McKenna and colleagues wrote in 2001 that ginkgo has a history of use in traditional Chinese medicine, that the seeds are the part most commonly employed there, and that standardized leaf extracts were widely sold as a phytomedicine in Europe and as a dietary supplement in the United States ([PubMed](https://pubmed.ncbi.nlm.nih.gov/11565403/)). NCCIH lists cough and diarrhea among the historical uses, alongside other conditions. The trials discussed below did not test either one. ## Which extract do the trials use? Diamond and Bailey (2013) report that EGb761, a special standardized extract, is the one used in most randomized controlled trials of ginkgo ([DOI](https://doi.org/10.1016/j.psc.2012.12.006)). A product made from a different extract may not match those results. The sources reached for this post do not date the extract's development, so this post does not give a date. Readers who want a trial-by-trial breakdown of another herb studied for memory can start with the [bacopa monograph](/ingredients/bacopa-monnieri). ## How did the Hiroshima survivor trees become a story? The University of Kentucky Urban Forest Initiative describes 170 trees in 55 locations within about 1.25 miles of the Hiroshima blast, after most trees and vegetation had been destroyed ([UKY](https://ufi.mgcafe.uky.edu/tree-stories/hiroshima-trees)). The city, tree experts and volunteers tended them afterward, and each carries a name plate reading *hibakujumoku*, or survivor tree. In 2011, a former director of the Hiroshima office of the UN Institute for Training and Research proposed sending seeds from those trees abroad, and the Green Legacy Hiroshima initiative was set up to do it. Ginkgo seeds from Shukkeien Garden went to Lexington, Kentucky, in one shipment. ## What did the big trials find? Three studies carry most of the modern record. | Study | Who was studied | Dose and length | Outcome | Result | Evidence grade | |---|---|---|---|---|---| | [DeKosky et al., JAMA, 2008](https://doi.org/10.1001/jama.2008.683) (GEM) | 3,069 US adults aged 75 or older | 120 mg twice daily, median 6.1 years | All-cause dementia | Hazard ratio 1.12 (95% CI 0.94 to 1.33), no reduction | Moderate | | [Vellas et al., Lancet Neurology, 2012](https://doi.org/10.1016/S1474-4422(12)70206-5) (GuidAge) | 2,854 French adults aged 70 or older with memory complaints | 120 mg twice daily of EGb761, 5 years | Conversion to probable Alzheimer disease | Hazard ratio 0.84 (95% CI 0.60 to 1.18), not significant | Moderate | | [Nicolaï et al., Cochrane, 2013](https://doi.org/10.1002/14651858.CD006888.pub3) | 477 people with intermittent claudication in 11 placebo-controlled trials | Varied | Walking distance | About 64.5 meters more (95% CI -1.8 to 130.7), not clinically significant | Strong (meta-analysis) | The surprise is in the GEM rates. The ginkgo group had 3.3 dementia cases per 100 person-years, against 2.9 in the placebo group, and the difference was not statistically significant ([DOI](https://doi.org/10.1001/jama.2008.683)). The GuidAge authors ran a later post hoc analysis that suggested a late effect, and they wrote that no definitive conclusions can be drawn from it ([DOI](https://doi.org/10.1007/s12603-015-0661-2)). The circulation evidence moved the same way. Intermittent claudication is leg pain on walking that eases with rest. A 2000 meta-analysis by Pittler and Ernst found a 34-meter difference in walking distance, which the authors called modest and of uncertain clinical relevance ([DOI](https://doi.org/10.1016/s0002-9343(99)00454-4)). The 2013 Cochrane update found no clinically significant benefit ([DOI](https://doi.org/10.1002/14651858.CD006888.pub3)). For the wider context, see the [heart and blood pressure guide](/health/heart-blood-pressure-complete-guide) and the [brain health guide](/health/brain-health-focus-complete-guide). ## What about the seeds and bleeding? Seeds carry the sharpest warning. A 2019 review in the Japanese journal *Yakugaku Zasshi* describes ginkgo seed poisoning with tonic-clonic convulsions and vomiting. It identifies the toxic compound, 4'-O-methylpyridoxine, which was purified from the seeds in 1985 ([DOI](https://doi.org/10.1248/yakushi.18-00136)). [NCCIH](https://www.nccih.nih.gov/health/ginkgo) says fresh seeds are toxic when taken by mouth, and that serious side effects have followed roasted seeds and the crude plant. For the leaf extract, NCCIH says ginkgo may raise the risk of bleeding in people taking anticoagulants such as warfarin. Diamond and colleagues made the same point in 2000 and advised caution with anticoagulants ([DOI](https://doi.org/10.1016/s0003-9993(00)90052-2)). NCCIH also says ginkgo may be unsafe during pregnancy. ## Bottom line Read the trial record before you read the label. Two large dementia trials did not show that ginkgo lowers dementia risk, and the 2013 Cochrane review found no clinically significant benefit for claudication. Ask a clinician before using ginkgo if you take an anticoagulant or are pregnant, and do not eat the seeds. ## Frequently asked questions **Why is ginkgo called a living fossil?** Ginkgo's genus has a fossil record that goes back to the Lower Jurassic, about 190 million years ago, and only one species survives. UCMP says the genus had five or six species in the Northern Hemisphere during the Cretaceous and was down to one by the Paleocene. NCCIH uses the same phrase. **How did ginkgo trees spread from China to Europe?** Buddhist monks grew the trees in mountain monasteries in China, and UCMP says the tree spread out of the mountains around 1100 AD. It was first planted in Europe in the early 1700s. Harvard's Widener Library credits Engelbert Kaempfer, who spent two years at the Dutch trading post at Nagasaki, with bringing the seeds to Europe. **What did traditional Chinese medicine use ginkgo seeds and leaves for?** McKenna and colleagues (2001) say the seeds were the part most commonly employed in traditional Chinese medicine, while standardized leaf extracts became the recent commercial form. NCCIH lists cough and diarrhea among the historical uses. Those are historical uses, and the trials cited in this post did not test them. **How did the standardized leaf extract come about?** The sources reached here describe the extract's place in the market, not its invention. McKenna and colleagues say standardized leaf extracts were widely sold as a phytomedicine in Europe and as a dietary supplement in the United States. Diamond and Bailey report that EGb761, a standardized extract, is the one used in most randomized trials of ginkgo. No development date is given here because no source for one was retrieved. **Which trials tested ginkgo extract, and what did they find?** The GEM trial, published in JAMA in 2008, randomized 3,069 adults aged 75 or older to 120 mg twice daily or placebo for a median of 6.1 years and found no reduction in dementia. GuidAge, published in Lancet Neurology in 2012, randomized 2,854 adults aged 70 or older with memory complaints to 120 mg twice daily or placebo for five years and found no significant reduction in conversion to Alzheimer disease. The 2013 Cochrane review found no clinically significant benefit for walking distance. **Why do ginkgo products carry a seed and leaf warning?** This post did not confirm a labeling rule that requires the warning, but the risks themselves are documented. NCCIH says fresh seeds are toxic when taken by mouth, and that roasted seeds and the crude plant have caused serious side effects. For the leaf extract, the documented concern is bleeding risk with anticoagulants such as warfarin. ## Next reads - [Brain health focus: the complete guide](/health/brain-health-focus-complete-guide): the reference page this post leaned on for the memory trials. - [Turmeric and curcumin: from Eastern texts to the capsule](/blog/history/history-of-turmeric-and-curcumin-from-ayurveda-to-isolation): another plant with a long traditional record, and the gap between a whole plant and an extract. ### Related reading - [The bacopa origin story, from Ayurvedic brahmi to memory trials](/blog/history/history-of-bacopa-from-ayurvedic-brahmi-to-memory-trials) - [The ginseng origin story, from Shennong to American export](/blog/history/history-of-ginseng-from-shennong-to-american-export)