Ginkgo

Common name: Ginkgo
Other names: Maidenhair tree
Latin name: Ginkgo biloba
Affinities: Nervous system, circulatory system
Actions: Nervine tonic, circulatory stimulant, nootropic, medhya rasayana
Specific indications: Cognitive problems, weak circulation, cold extremities, recovery after brain trauma, calf cramps
Diseases: Alzheimer’s(1*), dementia(1*), stroke(3), heart disease(3), sudden deafness(1),  hearing loss(2), anxiety(1), Raynaud’s phenomenon(1), peripheral arterial insufficiency(1), asthma(3), colitis(2), thrombosis(3), depression(3), headaches(3), CFS/ ME(3), neuralgia(2), tinnitus(3)
Parts used: Leaf

Ginkgo_biloba_1

Characteristics: Ginkgo is a deciduous tree that grows slowly and up to 125 foot tall (Kuhn and Winston, 2000). A single ginkgo tree can survive for up to 1000 years. The male and female trees and their flowers look slightly different. The male tree produces upright flowers that develop on a leaf axis. However, the female has a wider shape and crown, and the flowers have two ending ‘naked’ ovules on a stalk.

History: Ginkgo is the oldest tree on earth, it dates back to the Jurassic era around 200 million years ago (Castleman, 2001). Ginkgo is considered sacred throughout Asia where it is often planted in Buddhist temples. Ginkgo was thought to be good for the lungs and heart in China’s first well known herbal text, the Pen Tsao Ching (The Classic of Herbs). This can be attributed to the mythical emperor sage ‘Shen Nung’ who is said to have lived around 3000 B.C. Traditionally in Chinese medicine it has been used to treat asthma and chilblains, and swelling of the feet and hands due to cold and damp weather. The seeds were eaten as a digestive aid and to prevent drunkenness. Ayurvedic physicians in India associated ginkgo with increased life-span. Ginkgo trees were brought into Europe in 1730 and thus they are popular trees in parks and alongside paths throughout the world. However, herbalists in Europe ignored their medicinal properties until more modern times when the leaf extract became popular. This is a recent discovery as in ancient times it was the nut was used.

Current applications: Ginkgo is applied in Alzheimer’s, dementa, hearing loss, tinnitus, erectile dysfunction, atherosclerosis, varicose veins, and peripheral neuropathy (Winston, 2007). David Winston uses it in recovery from head trauma with bacopa, St. John’s wort, and holy basil. Ginkgo can be used alongside reishi, schisandra, and licorice to reduce inflammation of the repiratory tract. It may have use in treating other inflammatory disorders. It also may have use in the treatment of depression, chronic fatigue (ME), and headaches (Bartram, 2013). Ginkgo encourages circulation so may be used to increase the penetration of other herbs in the formula into the tissues.

Science: Ginkgo has an impressive array of scientific studies supporting its traditional use. Studies on experimental models demonstrate anti-oxidant activity, which is a plausible means by which ginkgo improves the symptoms of Alzheimer’s and dementia (Bridi et al., 2001). The mitochondrial cascade hypothesis assumes mitochondria dysfunction as a common step across a broad range of age associated cognitive disorders, it is thought that ginkgo which improves the function of mitochodria, somehow interfers with this process (Muller et al., 2017). In line with traditional views of ginkgo, one study found that ginkgo significantly increased the lifespan of rats compared with the control group (Winter, 1998).

In mice, ginkgo has been found to downregulate various inflammatory markers such as TNF-alpha, suppress the activation of macrophages, and could be used to both prevent and treat mouse colitis (Kotakadi et al., 2008). It displays anti-tumour properties in models (Zhou et al., 2010). It also has neuroregenerative properties in various experimental models and therefore is a potential treatment for conditions involving nerve damage (Hsu et al., 2004).

Ginkgo is one of the best studied herbal medicines in humans. There is convincing data supporting its application in Alzheimer’s and dementia in a high good quality clinical trial (Le Bars et al., 1997). Another double-blind placebo controlled study, although a little small, supports its use in Raynaud’s phenomenon (Muir et al., 2002). Two similarly sized well controlled studies imply its effectiveness in treating sudden deafness (Burschka et al., 2001) and peripheral arterial insufficiency (Bauer et al., 1983). Its apparent effectiveness in Raynaud’s and peripheral arterial insufficiency supports its traditional role as a circulatory stimulant. There is also strong support for its application in anxiety (Woelk et al., 2007). In summary, ginkgo is one of the herbs with the best scientific support and it is also very versatile.

Safety: Ginkgo is a safe and well tested herb that can be used by all people except there are concerns about its potential to interact with blood thinning drugs as aspirin, warfarin, or other anti-coagulant or antiplatelet medications. Therefore, if taking these drugs, it is best to avoid it.

Dosage: Tincture, 5-60 drops 3-4 times daily. Solid extract, from 120-240mg of extract per day, where 6000mg of dried leaf refers to 120mg of extract. Needs to be taken for 8 weeks before efficiency can be estimated.

Scientific Summary

Research on models

Anti-oxidant activity: One study reported an extract of ginkgo had anti-oxidant activity in rats (Bridi et al., 2001). An increase in the activity of the catalase and superoxide dismutase anti-oxidant enzymes was observed in the parts of the brain with treatment. Since Parkinson’s and Alzheimer’s diseases are often associated with oxidative stress the authors inferred reducing oxidative stress may be how ginkgo works.

Anti-aging activity: A study found that ginkgo fed to rats increased their lifespan relative to the control group (Winter, 1998). They also observed improvements in cognitive performance.

Anti-inflammatory activity: A study observed ginkgo extract supressed the activation of macrophages and in mice, and could be used to treat and prevent mouse colitis (Kotakadi et al., 2008). Various markers of inflammation were found to be down-regulated, including; iNOS, COX-2, and TNF-alpha.

Anti-tumour activity: One study found ginkgolic acids extract from gingko had anti-tumour activity as they inhibited tumour cell proliferation, cell division, and induced apoptosis (Zhou et al., 2010).

Neuroregenerative activity: A study reported using both in vivo and ex vivo models that an extract of ginkgo promoted growth of Schwann cells and increased the total number of myelinated axons (Hsu et al., 2004). The authors concluded the herb has potential for peripheral nerve regeneration and functional recovery.

Research on humans

Alzheimer’s and dementia: One study (n = 309, double blind placebo controlled) over 52 weeks found patients who took 120 mg/day of a ginkgo extract both stabilized and improved patients cognitive performance relative to the placebo (Le Bars et al., 1997). In addition, the authors remarked the extract seems very safe.

Raynaud’s phenomenon: A study (n = 22, double blind placebo controlled) conducted over 2 weeks found a highly significant improvement in attack frequency in patients treated with a ginkgo extract called Seredrin versus the placebo (Muir et al., 2002).

Sudden deafness: One study (n = 72, double blind drug reference controlled) found that patients treated with 200mg/day of ginkgo extract improved as much as those treated with the drug, pentoxifylline (Burschka et al., 2001).

Peripheral arterial insufficiency: A study (n = 79, double blind placebo controlled) observed over 6 months treatment with ginkgo extract reduced symptoms of the disease significantly compared with the placebo (Bauer et al., 1983).

Anxiety: One study (n = 107, double blind placebo controlled) found that when treated with 480mg/day of ginkgo extract patients experienced a significant reduction in their symptoms over 4 weeks (Woelk et al., 2007). The authors stated the herb is particularly suited to elderly patients with anxiety related to cognitive decline. They also noted the extract was safe and well tolerated.

References:

Bauer, U. “6-Month double-blind randomised clinical trial of Ginkgo biloba extract versus placebo in two parallel groups in patients suffering from peripheral arterial insufficiency.” Arzneimittel-Forschung 34.6 (1983): 716-720.

Bartram, Thomas. Bartram’s encyclopedia of herbal medicine. Hachette UK, 2013.

Bridi, R., et al. “The antioxidant activity of standardized extract of Ginkgo biloba (EGb 761) in rats.” Phytotherapy Research 15.5 (2001): 449-451.

Burschka, Martin A., et al. “Effect of treatment with Ginkgo biloba extract EGb 761 (oral) on unilateral idiopathic sudden hearing loss in a prospective randomized double-blind study of 106 outpatients.” European archives of oto-rhino-laryngology 258.5 (2001): 213-219.

Castleman, Michael. “The new healing herbs.” Bantam Book, New York (2001): 465-471.

Hsu, Shan-Hui, et al. “In vitro and in vivo effects of Ginkgo biloba extract EGb 761 on seeded Schwann cells within poly (DL-lactic acid-co-glycolic acid) conduits for peripheral nerve regeneration.” Journal of biomaterials applications 19.2 (2004): 163-182.

Kotakadi, Venkata S., et al. “Ginkgo biloba extract EGb 761 has anti-inflammatory properties and ameliorates colitis in mice by driving effector T cell apoptosis.” Carcinogenesis 29.9 (2008): 1799-1806.

Kuhn, Merrily A., and David Winston. Herbal therapy and supplements: a scientific and traditional approach. Lippincott Williams & Wilkins, 2000.

Le Bars, Pierre L., et al. “A placebo-controlled, double-blind, randomized trial of an extract of Ginkgo biloba for dementia.” Jama 278.16 (1997): 1327-1332.

Muir, Andrew H., et al. “The use of Ginkgo biloba in Raynaud’s disease: a double-blind placebo-controlled trial.” Vascular medicine 7.4 (2002): 265-267.

Müller, Walter E., et al. “Therapeutic efficacy of the Ginkgo special extract EGb761® within the framework of the mitochondrial cascade hypothesis of Alzheimer’s disease.” The World Journal of Biological Psychiatry (2017): 1-17.

Winston, David, and Steven Maimes. Adaptogens: herbs for strength, stamina, and stress relief. Inner Traditions/Bear & Co, 2007.

Winter, J. C. “The effects of an extract of Ginkgo biloba, EGb 761, on cognitive behavior and longevity in the rat.” Physiology & behavior 63.3 (1998): 425-433.

Woelk, H., et al. “Ginkgo biloba special extract EGb 761 in generalized anxiety disorder and adjustment disorder with anxious mood: A randomized, double-blind, placebo-controlled trial.” Journal of psychiatric research 41.6 (2007): 472-480.

Zhou, Chenchen, et al. “Antitumor effects of ginkgolic acid in human cancer cell occur via cell cycle arrest and decrease the Bcl-2/Bax ratio to induce apoptosis.” Chemotherapy 56.5 (2010): 393-402.