Description

Flavonoids are polyphenolic compounds found in various organisms (plants, fruits and vegetables), whether in their leaves, stems, flowers, fruits or pollen.

They are colour pigments that give these organisms their wide range of colours.

They mainly protect them from oxidation and the sun's harsh rays.

Flavonoids also contribute to the flavour of fruits and vegetables.

There are about 4,000 species, divided into four groups: quercetin (onions, broccoli, etc.), flavonones (lemon), catechins (tea, red wine) and anthocyanins (berries, grapes, etc.).

Flavonoids have been highlighted in particular by red wine, with the famous "French paradox", i.e. the notoriously low mortality rate of the inhabitants of Mediterranean regions, whose diet is essentially based on the consumption of red wine and saturated fats!

History

Flavonoids only entered the Western pharmacopoeia a few years ago, although their bioavailability is still not fully understood.

They were isolated by the scientist Eugène Chevreul in 1814, but it was not until 1937 that they were really discovered by Albert Szent-Györgyi, who highlighted their influence on reducing the permeability of blood vessels.

This Hungarian scientist was awarded the Nobel Prize for his research into vitamin C and the biochemical properties of flavonoids.

Sources

Citrus fruits, onions, red vines, apples, berries, witch hazel, gingko, hazelnuts, fine herbs, nettles, leeks... are the fruits, vegetables or plants that contain the most flavonoids.

They are also found in coffee, tea, wine, beer and chocolate (cocoa).

It seems preferable to eat (as much as possible) raw fruit and vegetables to preserve all the benefits of flavonoids.

Indications

Flavonoids are mainly recommended for their antioxidant action.

They help to protect the body from the harmful effects of pollution, consumption of toxic substances (alcohol, tobacco, etc.) or exposure to the sun, which are responsible for cellular ageing and senescence.

While free radicals are naturally produced by the body to fight bacteria and viruses, in some cases they can be produced in excess and break down cell walls, proteins or DNA.

This is where antioxidants come into play:

• Prevent cardiovascular disease
• Improve blood circulation
• Regulate blood pressure
• Treat allergies
• Prevent certain diseases and cancers
• Plant protection

Properties

Flavonoids are best known for their antioxidant properties.

They participate in the fight against free radicals, molecules derived from oxygen and nitrogen, which are involved in many degenerative processes and accelerate the ageing of tissues and cells.

The oxidative stress caused by these free radicals appears to weaken the body's health.

Natural defences are used to limit their effects, but sometimes the body cannot defend itself, especially in the elderly, and needs to find new weapons through diet.

It now seems essential for the body's well-being to eat a varied diet and at least 5 portions of fruit and vegetables a day.

The main sources of natural antioxidants are colourful fruits and vegetables and certain cereals.

According to some studies, their action against free radicals is even more effective than that of vitamins C and E.

In any case, they improve the action of these vitamins in the body by increasing their absorption and delaying their elimination.

Assets

The antioxidant role of flavonoids is explained by their high concentration of vitamin "P", as the person who discovered them called them.

This name was later abandoned because these substances do not meet the official definition of vitamins, as they cannot be considered essential to life.

Flavonoids help to increase the elasticity and resistance of blood vessels.

They also help to improve the flushing and dilation of the arteries, thus regulating blood pressure.

They also help fight against the alteration of collagen fibres, which are essential for maintaining cell health.

The side effects

Lowering blood pressure

Despite its beneficial effects on blood pressure regulation, there are risks.

These are related to vitamin C intake.

A good intake of vitamin C has been shown to lower blood pressure.

Taking flavonoids, especially those from grape seeds, has also been shown to have no effect on blood pressure.

However, taking both at the same time can cause blood pressure dysregulation in people with hypertension.

Excess caffeine

Some plants that are very rich in flavonoids also contain a lot of caffeine.

This is the case with tea, coffee and cocoa.

High consumption of foods rich in flavonoids leads to adverse effects of caffeine, such as heart palpitations or insomnia.

Various diseases

High levels of quercetin are likely to cause headaches or stomach pain.

It is important to consult your doctor before adding flavonoids to your diet or taking supplements.

Prevention

Certain population groups, such as pregnant or breastfeeding women, children and people with blood clotting disorders or on anticoagulant treatment, should seek medical advice before starting supplementation.

Interactions

In the diet, flavonoids enhance the effects of vitamin C by increasing its absorption and delaying its elimination.

There is a risk of interaction between quercetin and other dietary supplements or drugs such as anticoagulants or during chemotherapy.

Always seek the advice of your doctor.