GINKGO LEAF (Ginkgo biloba)

Latin: Ginkgo biloba
English: Maidenhair tree
Chinese: Bai guo ye / Yin guo ye

WHAT IT DOES: Purified ginkgo leaf is bitter and astringent in taste, and stimulating and warming in action.  It increases oxygen and blood flow to the brain and extremities, and increases nutrient and oxygen absorption by nerve

RATING: Silver

SAFETY ISSUES: Use cautiously with anti-coagulant drugs.  Do not use with pharmaceutical MAO inhibitors.  Avoid use at least 3 days prior to surgery. Excessive use may cause bleeding problems, bruising and/or micro-hemorrhages in the eye.

• Standardized extract (6% terpene lactones and 24% flavone glycosides): 40-60 mg two times per day
• 1:2 Tincture: 35 drops two to three times per day

The Ginkgo tree is a fascinating and beautiful living entity, reputed to have survived the Ice Age.  It is often planted along roadsides because of its ability to remain vibrant and alive in polluted city conditions.  Ginkgo leaf has shown a powerful effect on various aspects of brain and nerve function and cerebral circulation in more than 500 studies.  Some of its major uses include the treatment of vertigo and neurological disorders, memory and concentration problems, and diminished intellectual capacity due to poor circulation.  It may also delay the onset of Alzheimer’s disease.

When standardized in a 50:1 concentration, ginkgo belongs to a category of substances known as phyto-pharmaceuticals—halfway between crude herbs and pharmaceuticals.  The herb is standardized because it is necessary to remove some slightly toxic phyto-chemicals from ginkgo before use, though the level of concentration does not need to be very strong.  Nai-shing uses a 5:1 powder concentrate in her formulas, and I often use the 1:2 tincture.  No adverse effects have ever been reported in these benign forms.  I think these lower concentrations are best if you are creating a formula and want a milder medicine.  I have found that well-prepared organic tinctures can often produce the desired results in very low dosage.

There have been limited reports of people developing bleeding or hemorrhage while taking ginkgo at the same time as anti-coagulant or platelet-inhibiting drugs.  However, when you consider a German survey of data on millions of patient-years patient use (which means billions of ginkgo pills taken) without any reports of significant bleeding, I would think that the risks are very mild even in this area (DeFeudis, 1991).  Caution is still wise, of course, and I do not suggest taking ginkgo if you are on blood-thinning medications, unless you consult a qualified health care practitioner.

I have found it very valuable for improving mental alertness and mood in some elderly patients, though I seldom use it alone.  If taken in excess it can sometimes cause irritability.  I have rarely found it to be an effective memory enhancer in younger persons with good circulation, though scientific reports do show some benefit on short-term memory.  Ginkgo can be very useful in treating some cases of tinnitus, but you need to use it for a couple of months to see results.  The high level of good scientific test results found with ginkgo are due to the fact that so much research has been done.  Many, many others herbs will reach this level of proof in the coming years.

Research Highlights

• Researchers performed a meta-analysis of all studies of ginkgo treatments for cognitive function in Alzheimer’s patients.  They concluded that there was a “small but significant effect of 3- to 6-month treatment with 120 to 240 mg of ginkgo biloba extract on objective measures of cognitive function” (Oken et al., 1998).

• Among the most encouraging studies are those that show improvements in depression with the elderly.  Clinically depressed patients taking standard medications improved significantly with the addition of ginkgo (Schubert and Halama, 1993).

•  Equally encouraging was an open trial showing that treatment with ginkgo was 84% effective in neutralizing sexual dysfunction caused by anti-depressant medicines, especially selective serotonin reuptake inhibitors (SSRIs) (Cohen and Bartlik, 1998).

• Animal studies have shown that ginkgo’s effect on nerve cell membranes may possibly restore age-related declines in serotonin receptor sites (Huguet et al., 1994).  If this also occurs in humans, it may explain some of the beneficial effects of ginkgo on mood in the elderly (reported in Murray, 1996).

• Controlled trials have shown effectiveness with tinnitus (Meyer, 1986), acute cochlear deafness (Dubreuil, 1986), senile macular degeneration (Lebuisson et al., 1986), and diabetic skin lesions (Pepe et al., 1999).

• Patients undergoing cardiopulmonary bypass often have severe problems during recovery, including tissue necrosis.  In one randomized controlled trial testing ginkgo extract (EGb 761), patients were given either the extract or a placebo five days prior to surgery. Doctors collected blood samples at crucial stages of the operations and up to 8 days post-surgery.  Researchers saw a reduction in free radical generation and a significant delay in leakage of oxygen-carrying muscle proteins.  These results suggest that pre-surgical administration of ginkgo extract can help prevent complications (Pietri et al., 1997).

• In an animal study using ginkgo in combination with superoxide dismutase (SOD), ginkgo’s inhibition of platelet activating factor (PAF) significantly reduced oxidative damage to intestinal membranes after induced ischemia in rats (Droy-Lefaix et al., 1991).  This is a convincing argument for the use of ginkgo with low temperature dried wheat sprouts (which provide SOD) as an important intervention after ischemic injury, such as optic neuritis.

• When administered to Chernobyl workers involved in the infamous nuclear accident, ginkgo leaf extract inhibited blood levels of radiation-induced chromosome damaging factors by 83%.  Researchers noted, however, that only the complete extract (as opposed to isolated components) exerted significant effects (Alaoui-Youssefi et al., 1999).

• Ginkgo increased pain-free walking distance more than 300% in diabetic and non-diabetic patients with arterial blockage disease (Li et al., 1998).

• In a randomized controlled trial, ginkgo leaf oral liquor was shown to significantly reduce clinical symptoms, airway hyper-reactivity and pulmonary function of asthmatic patients (Li et al., 1997).  It has also shown benefit in children’s asthma (Keville, 1996).

• In a multi-center randomized controlled clinical trial of 545 schizophrenic patients receiving 120 mg of ginkgo three times a day in addition to their regular neuroleptic medication, researchers found a general reduction in negative symptoms including thought disturbance
(Luo et al., 1997).

• A double blind three-month study of 70 patients with vertigo showed that ginkgo significantly reduced the intensity, frequency and duration of the disorder.  By the end of the trial, 47% of the patients taking ginkgo were symptom free, compared to 18% of those who received the placebo (Haguenauer et al., 1986).

• A randomized controlled study of ginkgo extract found it effective in treating breast and leg swelling and mood changes during PMS episodes (Tamborini and Taurelle, 1993).

• In a controlled blood flow study on ten healthy subjects, gingko decreased red blood cell aggregation (clumping) by 15%, and increased blood flow into the capillaries under the fingernails by 57% two hours after ingestion (Jung et al., 1990).

• Blood stasis can cause oxygen starvation of the venous lining tissue, leading to the development of varicose veins.  In a randomized controlled clinical trial, ginkgo extract was one of four medicines shown to reduce circulating cells indicative of venous wall damage (Janssens et al., 1999).

• In a randomized, double blind and placebo controlled 5-way crossover design study ginkgo leaf extract was shown to improve memory, the best results occurring at a dose of 120 mg per day.  The benefits were more apparent in individuals over the age of 50 (Rigney et al., 1999).

• In a controlled crossover study, ginkgo was shown to benefit glaucoma patients by increasing ocular blood flow (Chung et al., 1999), and an earlier controlled study of blood flow to the retina showed similar results.  Researchers concluded that ” damage to the visual field by chronic lack of blood flow (is) significantly reversible” (Raabe et
al., 1991).