The Ginkgo biloba, or Maidenhair tree, is one of the oldest surviving plant species, dating back over 270 million years. Ginkgo biloba has been used in Chinese medicine for thousands of years to improve blood circulation. By increasing blood flow to the peripheries, Ginkgo biloba can improve memory and cognitive decline, Raynaud’s, tinnitus and erectile dysfunction.

How Ginkgo biloba works

The fan-shaped Ginkgo leaves contain unique antioxidants called ginkgolides and bilobalides. These relax blood vessel walls and dilate arteries through an effect on nitric oxide (NO), which is similar to the way in which to l-arginine and drugs such as sildenafil (Viagra) work.

At therapeutic doses, Ginkgo biloba increases the flexibility of red blood cells so that oxygen-rich blood flows more freely through tiny capillaries to improve blood flow to the peripheries.

Ginkgolides also reduce the effects of platelet activating factor (PAF) – a blood clotting substance that has been linked to migraine, allergies, asthma and blood clotting disorders such as heart attack and stroke.

Ginkgo biloba benefits

A 49 million-year-old fossilised Ginkgo biloba leaf

Ginkgo has a number of beneficial effects on the circulation. Researchers have found that Ginkgo biloba can increase blood flow to the fingers by 57% within just one hour. By improving blood flow to the hands and feet, Ginkgo biloba can help treat chilblains and Raynaud’s phenomenon, in which blood flow to the fingers and toes is constricted when cold.

The results form 14 trials, involving 739 people with intermittent claudication (leg pain on walking due to poor circulation to muscles) found that taking Ginkgo biloba supplements increased walking distance by a further 64.5 metres on a flat treadmill (at a speed of 3.2km/hour) before leg pains occurred, compared with placebo.

Being able to walk an extra 200 feet or so before developing leg pains is a meaningful amount when you have intermittent claudication; however, the reviewers thought this was not enough to provide a ‘clinically significant benefit’.

Ginkgo biloba and coronary heart disease

In people with coronary heart disease, Ginkgo biloba may also help to increase blood flow through the coronary arteries. This was tested in 80 people with coronary artery disease, half of whom took a Ginkgo biloba extract and half were controls. Blood flow through their coronary arteries was measured before and 2 weeks after taking Ginkgo biloba extracts, and significant improvements were seen compared to controls.

Ginkgo biloba and stress

Ginkgo biloba dilates blood vessels and may have beneficial effects on blood pressure. A study involving 70 healthy volunteers found that taking 120mg Ginkgo biloba extract reduced the rise in blood pressure that occurs during times of stress, without affecting the heart rate. Salivary levels of cortisol (a stress hormone) were also reduced in those who took Ginkgo biloba extract. This suggests that Ginkgo biloba acts as an adaptogen to reduce the acute effects of stress.

Ginkgo biloba and blood pressure

A small study involving 20 people found that taking Ginkgo biloba extracts (120 mg/day at bedtime) for 3 months reduced blood pressure by 7/18 mmHg.

However, a larger study involving 3,069 older people (average age of 79 years) at high risk of dementia, found that taking 240mg Ginkgo biloba a day for an average of 6 years did not reduce blood pressure or the incidence of hypertension compared with placebo.

The researchers suggested that it is possible that the antihypertensive effects of Ginkgo biloba are not effective in elderly people at known high risk of dementia, especially those with long-standing hypertension, due to age-related aortic stiffness.

Ginkgo biloba benefits for men

Ginkgo increases the production of nitric oxide which dilates arteries in the same was a sildenafil (Viagra) and related drugs. Ginkgo biloba also has a relaxant effect on smooth muscle cells within the erectile tissues of the penis. These two actions can help to strengthen and maintain an erection in men with poor circulation.

A study involving 50 males with impotence found that all those who had previously relied on injectable drugs (papaverine) to achieve an erection regained potency after taking 240mg Ginkgo biloba every day for 9 months. Of the 30 men who were not helped by medical drugs, 19 regained their erections with Ginkgo biloba extracts.

Ginkgo biloba extracts are often combined with other ingredients such as Panax ginseng, l-arginine and Horny Goat Weed.

Ginkgo biloba and memory

Ginkgo biloba leaf extracts can boost blood flow to the brain to help improve memory, concentration and the ability to think straight (cognition), especially in older people. Ginkgo biloba was found to improve free recall memory effects in middle-aged healthy volunteers.

The results from studies involving 1,200 people with poor memory and other cognitive symptoms, found that Ginkgo biloba supplements at a dose of 240mg per day were more effective than placebo for improving cognition (ability to think straight). Cognitive symptom scores improved by around 25%.

Ginkgo is often combined with other active ingredients – known as nootropics – to help improve memory and cognition.

Ginkgo biloba for dementia

As well as improve blood flow, and the delivery of glucose, oxygen and other nutrients to the brain, laboratory studies suggest that Ginkgo biloba has protective effects on brain cells (neurones) to reduce the build-up of amyloid which is associated with some forms of dementia.

A modern-day Gingo biloba leaf

Some trials involving people with dementia show that Gingko extracts can improve apathy/indifference, anxiety, irritability, depression, sleep and night-time behaviour compared with placebo.

Seven trials involving 2,625 outpatients compared the effects of taking Ginkgo biloba for 22 to 26 weeks against placebo. There were significant improvements in cognition and the ability to carry out activities of daily living in those taking Ginkgo biloba compared with placebo.

Benefits are mainly seen in those taking 240mg Ginkgo biloba per day for 22 weeks or longer.

The results from another nine trials, involving over 2,500 people, found that Ginkgo biloba supplements (240mg per day) were able to stabilise or slow the decline in behaviour and daily function in people with dementia, including Alzheimer’s disease, with no safety concerns.

Ginkgo biloba and tinnitus

Some trials have shown benefit in treating tinnitus with Ginkgo biloba, but some have not. It may work best where symptoms are due to reduced blood flow.

Ginkgo biloba for dyslexia

A small Italian study involving 15 children (aged 5 to 16 years) with dyslexia found that taking a single morning dose of 80mg Ginkgo biloba improved scores in standardized tests for dyslexia. Children should only take Ginkgo biloba under medical supervision, however.

Ginkgo biloba for migraine

Because ginkgo improves cerebral circulation, and blocks PAF, it has been used to treat migraine headaches. When 25 adults suffering from migraine with aura took Ginkgo biloba (plus coenzyme Q10, vitamin B2 and magnesium at the onset of aura, the duration of symptoms reduced significantly. In 18% of those with typical aura plus migraine, the pain phase disappeared altogether.

Gingko biloba and diabetes

The effect of Ginkgo biloba on insulin secretion within the pancreas was investigated in people with type 2 diabetes.  Ginkgo biloba was found to improve circulating insulin levels during an oral glucose tolerance test in those who were taking oral hypoglycaemic drugs, but not in those using dietary control only.

The researchers suggested that Ginkgo biloba may improve insulin production in people with pancreatic exhaustion, either by ‘resuscitating’ previously exhausted pancreatic cells (eg by improved blood flow) or by increasing the activity of the few remaining functional insulin-secreting cells. If taking Ginkgo and using hypoglycaemic drugs, it is important to monitor your blood glucose levels closely.

Ginkgo biloba dose

The usual dose is 120mg (equivalent to 6000mg whole Ginkgo leaves) to 240mg per day. Seek advice before taking higher doses used in clinical trials.

Select extracts standardised to provide a known amount of ginkgolides: eg at least 24%.

Ginkgo is often combined with ginseng – another herb known for its anti-ageing, tonic benefits.

Select a product made to a pharmaceutical standard known as GMP, and which contains the lowest possible amount of an undesirable substance called ginkgolic acid.

Ginkgo biloba safety

In a review of over 70 clinical trials, side effects occurred in less than 1% of people. Headache has been reported as a rare side effect of ginkgo biloba therapy.

Because Ginkgo biloba has a blood thinning action, there is a theoretical increased risk of bleeding. However, studies involving a total of 1985 adults did not find any evidence of a higher bleeding risk associated with standardized Ginkgo biloba extracts.

Seek medical advice before taking Ginkgo if you are taking any prescribed drugs, especially blood thinning treatments, antidepressants and diabetes medications, as interactions can occur.

If you have diabetes, monitor blood glucose levels closely.

Do not to exceed manufacturer’s doses.

Image credits: brosova/bigstock; kevmin/wikimedia; andrikkos/wikimedia