Ginkgo biloba: What are its desirable and undesirable effects? Does it promote memory?

Ginkgo biloba is one of the oldest living tree species in the world. The average age of a single tree can be up to 3,000 years.

However, the grower will have to wait for the first blossoms. It takes approximately 20 years for a double-leaved gingko to flower. The gingko is quite a giant, growing up to 40 metres tall.

Ginkgo is a dioecious plant.

The mature male trees produce flowers in spring. In autumn, the female trees produce yellow-brown fruits that resemble apricots. However, these fruits are not edible. Their flesh smells unpleasant and irritates the skin.

The only edible part of the fruit is the stone, but only when cooked by roasting and in small quantities. The stone of the ginkgo fruit is similar to that of a hazelnut.

Ginkgo is native to the Far East, specifically to southeastern China, Japan and Korea.

In these countries, it grows naturally over large areas in deciduous forests that stretch to high altitudes, even up to 1100 m above sea level.

Its seeds were first brought to Europe in the 1730s and were planted in Dutch urban gardens.

Urban gardens and parks are its typical refuge in Europe. Ginkgo is an undemanding plant for growers. It does not choose its soil type, but thrives best in sunny locations.

It is also an ideal tree for the city because of its exceptional resistance to pollution, carbon monoxide and sulphur oxides. After the nuclear attack on Nagasaki and Hiroshima in Japan, ginkgo trees were the first to regain their leaves.

The leaves are the first distinguishing feature of the ginkgo biloba. It is the appearance of the leaves that gave the ginkgo its generic name 'two-leaved'.

The leaves are flat. But they're not true leaves.

Ginkgo is the only living member of the very old order Ginkgoales. They are a gymnosperm plant that is closer in development to conifers than to deciduous trees.

The typical leaf of the Ginkgo is therefore actually a uniquely shaped needle.

The relatives and ancestors of this species date back to the Mesozoic Era, i.e. 150 to 200 million years ago. It can therefore be said that the dicotyledon is a 'living fossil'.

The use of ginkgo biloba in medicine

Ginkgo biloba is a fairly thoroughly researched plant in terms of its chemical constituents. In fact, a long list of compounds it contains has been described. Each of them has a potential effect on the human body.

Among the most important are ginkgolides, bilobalide, ginkgolic acid, flavonoids (especially biflavonoids), triterpenes, carotenoids, polyprenols, essential oils, aromatic acids, ascorbic acid, D-glucaric acid, quinic acid, shikimic acid, coumarins, lipids, hydrocarbons, carbohydrates, glycerol, tannins and the highly toxic compound ginkotoxin.

It is the latter compound that has the greatest effect on the physiological processes of all mammals, and man is no exception.

Ginkotoxin is mainly found in the raw seeds of the plant. The concentration of ginkgo toxin increases during the growing season and peaks at the end of August. Ingesting raw ginkgo seeds is therefore very dangerous. These seeds are poisonous.

Children between the ages of 1 and 3 are most at risk. Intoxication can occur from ingestion of very small amounts.

The worst effects of ginkotoxin intoxication include epileptiform seizures, unconsciousness, paralysis of the limbs, ventricular fibrillation and cardiac arrest.

In Japan, roasted ginkgo biloba seeds are a household delicacy.

Roasting and boiling significantly reduces the concentration of ginkgo toxin. This is also due to the solubility of ginkgo toxin in water. Even so, processed ginkgo seeds still contain a certain amount of the dangerous toxin. Therefore, they are not recommended for consumption.

The maximum safe amount is 50 roasted seeds.

Ginkgo is commonly available as an extract in tablets, capsules or as a tea. These preparations are obtained by drying mainly the leaves of ginkgo biloba. The effects of ginkgo have been investigated several times in scientific studies. A special extract with the designation EGb 761 has been used for this purpose.

The effect of ginkgo on the vascular system

The most useful components of ginkgo are considered to be flavonoids, which have strong antioxidant effects, and terpenoids, which help improve blood circulation by dilating blood vessels and reducing platelet clumping.

The positive effect on blood flow in the brain is considered to be the most popular. Terpene lactones (ginkgolides), which inhibit PAF and facilitate blood flow, play a major role in this effect.

Higher doses of ginkgo have a vasoactive effect on blood vessels and veins. This is associated with increased tissue blood flow, improved peripheral and cerebral blood flow, ocular blood flow and microcirculation.

Because of these properties, ginkgo is used as a supportive treatment for vascular diseases of the extremities, such as vascular claudication, tinnitus and dizziness of vascular origin.

Antioxidant and anti-inflammatory properties of ginkgo

Improving blood flow through the brain, reducing ischemia-reperfusion injury and inhibiting platelet clumping are mechanisms involved in the prevention and improvement of vascular dementia.

In Alzheimer's dementia, the neuroprotective effects of ginkgo are likely to apply.

These include, in particular, antioxidant effects, antiapoptotic effects on cells, anti-inflammatory effects, protection against mitochondrial dysfunction, amyloidogenesis and subsequent amyloid b aggregation, ion balance, modulation of tau protein phosphorylation, and very likely induction of growth factors.

Mitochondria are cellular organelles that provide cellular respiration and metabolism. Abnormal mitochondrial function is associated with pathological changes related to the development of Alzheimer's dementia.

Ginkgo has a protective effect on mitochondria. This is also related to its antioxidant effects. The mitochondrial respiratory chain is a major target and source of reactive oxygen species, which cause oxidation of various compounds and metabolic products.

The flavonoids contained in ginkgo leaves "cleanse" the cells of these reactive oxygen species.

In addition, ginkgo has antiapoptotic effects.

Apoptosis is controlled cell death, i.e. the death of the cell. It exerts its anitiapoptotic effect through intracellular apoptosis signalling pathways. In particular, flavonoids and terpenes play an important role in this process.

What to watch out for when taking ginkgo biloba?

Ginkgo is known in the population as a memory-improving herb. Tea made from its leaves is mainly drunk by university students in exam period or older adults who lack energy.

However, beware, ginkgo in larger quantities can cause serious side effects and unpleasant drug interactions.

Interactions with other drugs

• Alprazolam is a medication used to relieve symptoms of anxiety. Taking ginkgo may reduce the effectiveness of this medication.
• Anticoagulants and antiplatelet agents (anopyrine, warfarin) are drugs that reduce blood clotting. However, ginkgo also potentially has such an effect. Their concomitant use may cause increased bleeding.
• Anticonvulsants (valproate, carbamazepine) are drugs used to lower seizure thresholds, e.g. in the treatment of epilepsy. Large amounts of ginkgo toxin, also found in ginkgo leaves, increase the risk of seizures and reduce the effectiveness of anticonvulsants.
• Antidepressants (fluoxetine and imipramine) are drugs used to treat depressive syndrome. Taking ginkgo reduces their effectiveness and increases the risk of depressive episodes.
• Statins (simvastatin and atorvastatin) are cholesterol-lowering drugs. Ginkgo reduces the effectiveness of these drugs and increases the risk of atherosclerosis of the blood vessels.
• Antidiabetic drugs are drugs that regulate blood glucose levels in diabetes. Ginkgo can alter the body's response to these drugs, putting the patient at risk of hyperglycaemia or, conversely, hypoglycaemia.
• Non-steroidal anti-inflammatory drugs (ibuprofen) are drugs used to treat acute pain. Again, there is an increased risk of bleeding when these drugs and ginkgo are taken together.

Adverse side effects of ginkgo

Some people may also experience unpleasant side effects from ginkgo. If you experience any of the following symptoms, stop taking ginkgo.

• Headaches
• Dizziness
• Heart palpitations
• Stomach irritation
• Constipation
• Allergic skin reactions

Every medication you take carries the risk of allergic reactions. Natural products such as ginkgo biloba are no exception.

An allergy, or hypersensitivity reaction, is manifested by red skin, a minor rash, swelling and itching of the skin on the face, tongue, around the eyes or throat.

The most serious form of allergic reaction is anaphylactic shock, which is mainly manifested by breathing difficulties.

Ginkgo produces fruits that have a very irritating pulp. Contact with this pulp can cause skin irritation and a contact allergic reaction. In addition to the pulp, the pollen from its flowers is also aggressive to the skin.

For whom is ginkgo not suitable?

Some groups of people should avoid taking ginkgo.

This group of people includes epileptics and people with an increased risk of seizures.

Another group is older people who have a congenital bleeding disorder or people who are taking anticoagulant treatment such as warfarin.

Individuals who take antiplatelet drugs such as acylpyrine or who take large amounts of painkillers such as ibuprofen are also at increased risk of bleeding.

Ginkgo should also be avoided by patients with diabetes. If you are diabetic and still take ginkgo biloba extract, monitor your blood sugar levels carefully.

The last group of people for whom ginkgo is not the best choice are pregnant women and nursing mothers.

Ginkgo has not been shown to have a direct negative effect on the fetus or breast milk. However, ginkgo biloba contains a large number of active substances whose effect has not yet been studied in detail. Therefore, it is not advisable to take ginkgo extracts during this period.