Antioxidants and flavonoids are often mentioned in the context of healthy diet and cosmetic products. Most often stressed is these compounds’ capability to eliminate free radicals, thus slowing down the aging process. It’s true, but how exactly does this process work… and what exactly are flavonoids?
Seven thousand flavonoids
Flavonoids (or bioflavonoids) are secondary metabolites of plants and funghi. We currently know about 7.000 flavonoids, divided into: flavanones, flavanonols, flavanes isoflavones, anthocyanins, chalions, aurones, flavonols and procyanidins. The basic structure of the molecule consists of benzene rings with an added heterocyclic pyran or pyrene ring. As the carbon atoms – basis of every benzene ring – can undergo hydroxylation, methoxylation, glycosidation and acylation, a great variety of flavonoids with various properties has been observed so far. Due to the presence of large amounts of hydroxyl groups in their structure, the flavonoids exhibit strong antioxidant properties, depending on the number and location of those hydroxyl groups – the more of them, the stronger the antioxidant activity.
Sounds complicated? Without getting to deep into the chemical nomenclature, flavonoids are simply natural, water-soluble chemicals that serve as the plants’ most important pigments, they are also antioxidants, insectsocides and fungicides. They are distributed in all parts of plants: their fruits, stems, flowers, leaves, roots and seeds. The flavonoids are most common in citrus fruits, vegetables (beetroots), as well as in herbs, vines and in hemp, where the content of flavonoids in leaves and flowers reaches up to 2.5% of dry mass. Just these few examples points to the fact that the flavonoids are easiest to find in plants of intense colours and aromas, not coincidencally in those known for their health benefits.
The main function of flavonoids is to protect plants, and, at the cellular level, to serve as cell cycle regulators. Supplied with food for the human body, the flvonoids exhibit high biological activity and display antioxidant, anti-inflammatory and antiallergic properties.
Antioxidant properties of flavonoids
To explain the potential of flavonoids to neutralize free radicals, we must first understand what the free radicals actually are. To put it simply – these are molecules containing unpaired electrons. Each O2 particle contains an even number of electrons, but in processes that occur in the body, such as in the process of oxygen conversion in the mitochondria, it happens that the atom loses an electron. Such an unstable oxygen particle “tries” to get back to balance by jostling an electron from another atom encountered in its path; and this does not have to be another oxygen atom, it may be, for example, any atom of protein molecule. The accumulation of such processes destroys the structure of the protein and damages the cell membrane, leading to its death.
The antioxidant properties of flavonoids are based on inhibiting the activity of enzymes involved in the formation of free radicals and in the elimination of active free radicals. Flavonoids are chelators of metals that initiate oxidative processes (chelators are – grossly simplifying – compounds that permanently bind simple elements, eg hemoglobin is a cheletor of iron); in addition, flavonoids prevent oxidation of vitamin C and other detrimental reactions caused by active oxygen.
Health benefits of flavonoids
Preventing the formation of free radicals is not the only beneficial effect of flavonoids. These compounds exhibit a number of other health benefits. Flavonoids are characterized by multidirectional biological activity and act positively on the whole body, especially within the circulatory system. They play a very important role in protecting of the cardiovascular system: they lower blood pressure, improve blood vessel flexibility, slow down cholesterol deposition in blood vessel walls, inhibit platelet aggregation.
How do specific flavonoids work?
Anthocyanins improve vision by stimulating ocular microcirculation and improving visual acuity at dusk. Isoflavones have an estrogenic effect and complement estrogen deficiency, so they can relieve menopausal symptoms. Cannabis-specific cannaflavons have anti-inflammatory properties and they inhibit the development of infection. Apigenin has an anxiolytic effect and can regulate the level of neurotransmitters. Finally, quercetin has antiviral properties. It is also important to know that flavonoids in general strengthen the immune system.
Flavonoids are commonly used in cosmetics due to their positive effect on maintaining skin healthy and young. Creams and cosmetic products containing these compounds smooth the skin and moisturise it, preventing formation of wrinkles, they also help in collagen synthesis, have anti-edema properties and protect against UV rays.
Recently, there has been more and more talk about the the potential anti-cancer effect of flavonoids. Although there is indeed a link between the incidence of cancer and the diet rich in flavonoids, the mechanism of the process that reduces the risk of cancer is not fully understood; it is presumed to be partially related to the antioxidant properties of flavone compounds.
Flavonoids in the diet
The best sources of these compounds are fruits (especially citrus fruits), vegetables (beets, legumes), herbs and spices and red wine. It is recommended to consume 1 to 2 grams of flavonoids a day, with the increased need for those suffering from impaired immunity or cardiovascular problems; alcohol, smoking cigarettes and stress also increased the nees for anti-oxidants such as flavonoids.