Antioxidant Flavonoids » in Foods, Citrus Fruits, Properties…

Flavonoids are a family of naturally water-soluble compounds. Their function is to protect plants and prevent oxidative stress in humans. They are substances derived from plants and obtained from fruits, seeds, and vegetables. They help against microbes and have properties and benefits for human health.

The most well-known and used flavonoid is isoflavone, although there are different types according to their structure, being an extremely important element in the fight against skin aging and other vital organs.

What are Flavonoids

They are secondary metabolites of plants, that is, chemical compounds naturally produced by vegetables, legumes, fruits, and other types of herbs. Their role in the plant is not essential as the plant can survive without flavonoids, unlike primary metabolites which are essential.
Their synthesis is from phenylalanine and 3 malonyl-CoA, an essential amino acid present in many plants and plant-based foods. It is also necessary for their synthesis.

What are flavonoids and what are they for

What are flavonoids used for?

Flavonoids, along with bioflavonoids, have antioxidant properties in the human body. When ingested through vegetables containing them, they have antimicrobial effects; flavonoids serve to eliminate microbes, viruses, bacteria, and microscopic pathogens.
Furthermore, it has been proven by various studies that they have the property of reducing the risk of heart diseases, which is one of the reasons why they are considered healthy metabolites.

Another benefit of flavonoids is their anticancer effects, being highly regarded in medicine for their effects against microbes and their properties in protecting against the formation of malignant tumors.

Types of Flavonoids (Classification)

Types of flavonoids, names, and classification
Based on their chemical form, the structure of their molecular skeleton, several types of flavonoids can be classified as follows:

  • Chalcones.
  • Flavones.
  • Flavonols.
  • Flavanediols.
  • Anthocyanins.
  • Condensed tannins.
  • Aurones.

Flavonoids or bioflavonoids have antioxidant properties in the human body. They act by protecting against inflammation and enhancing the action of other active substances. Each flavonoid has effects for different situations, all possessing antioxidant properties, blocking free radicals.

Flavonoids in Plants

Flavonoids in plants and vegetables
In plants, they have the ability to increase the coloration of leaves and flowers. Ornamental plant growers produce them to enhance the shades of certain plant species, making them stronger and brighter.

It is common for plants with more colorful leaves and flowers to have a higher amount of flavonoids and polyphenolic compounds. This quantity of coloring pigments can also be expressed in fruits and tubers.

List of Plants with Flavonoids

  • Acai Berry (Euterpe oleracea).
  • Apricot (Prunus armeniaca).
  • Garlic (Allium sativum).
  • Almond (Prunus dulcis).
  • Alpinia officinarum.
  • Celery (Apium graveolens).
  • Blueberries (Vaccinium).
  • Chokeberry (Aronia melanocarpa).
  • Rice (Oryza sativa).
  • Cannabis sativa.
  • Blackcurrant (Ribes nigrum).
  • Bauhinia longifolia.
  • Eggplant (Solanum melongena).
  • Cherry (Prunus cerasus).
  • Plum (Prunus subg. Prunus).
  • Barley (Hordeum vulgare).
  • Onion (Allium cepa).
  • Kale (Brassica oleracea var. sabellica L.).
  • Eucryphia.
  • Indian Trumpetflower (Oroxylum indicum).
  • Black Raspberry (Rubus occidentalis).
  • Raspberry (Rubus idaeus).
  • Mung Bean (Vigna radiata).
  • Redcurrant (Ribes rubrum).
  • Helichrysum aureonitens.
  • Tridax procumbens (St. John’s Grass).
  • Purple Corn (Zea mays).
  • Mango (Mangifera indica).
  • Apples (Malus x domestica).
  • Peach (Prunus persica).
  • Orange (Citrus × sinensis).
  • Pecan (Carya illinoinensis, pecan or pecan).
  • Acai Palm (Euterpe oleracea).
  • Parsley (Petroselinum crispum).
  • Sweet Pepper (Capsicum annuum).
  • Cape Leadwort, Blue, Jasmine (Plumbago capensis, Ceratostigma willmottianum, etc.).
  • Lettuce (Lactuca sativa).
  • Alpinia galanga Rhizome (Alpinia officinarum Hance).
  • Rheum nobile.
  • Rhododendron (Rhododendron mucronatum).
  • Noble Rhubarb.
  • Sikkim Rhubarb.
  • Scutellaria baicalensis.
  • Scutellaria lateriflora.
  • Tea (Camellia sinensis).
  • Tomato (Solanum lycopersicum).
  • Thyme (Thymus).
  • Red Clover (Trifolium pratense L).
  • Wheat (Triticum spp).
  • Veronicastrum.
  • Grapevine (Vitis).
  • Blackberry (Rubus fruticosus).

In reality, most plants have flavonoids, if not all. Each species contains different proportions of secondary metabolites and compounds derived from polyphenols, with the most important being the plant species mentioned.
However, the list is so extensive that it is impossible to include them all. A simple way to detect that a plant has many flavonoids is through its color; the more red, purple, or dark-toned it is, the more likely it is to be a plant with a high content of isoflavones, chalcones, flavonols, and anthocyanins. However, each variety can contribute different amounts of each flavonoid subgroup.

Where are Flavonoids Found in Plants? (Plant Parts with the Most Flavonoids)

Parts of plants with more flavonoids
The highest amount of flavonoids is present in the leaves and flowers of plants. They can also be extracted from the fruits that we consume. Seeds are also a significant source of flavonoids.

Flavonoids are commonly found in the external and aerial parts of plants, although there are examples of tubers like onions where they are also present. For example, onions contain the flavonoid quercetin 4’-D-glucosides.

Discovery

Gregor Johann Mendel
The experiments of Gregor Johann Mendel in the 19th century were made possible by flavonoids when he could track the DNA change in a variety of peas, thereby concluding one of humanity’s great laws, «Mendel’s Laws.» These were possible because the author could trace the inheritance of the genes that flavonoids possessed and that gave color to the peas used in the experiment.

Since then, science has experimented several times on the antioxidant properties of flavonoids, first on animals, in vitro cultures, and subsequently verifying the results in the human body.

Today, there is no doubt about the benefits of flavonoids for human health, always considering the different classes such as anthocyanins, isoflavones, or using each flavonoid individually like quercetin, luteolin, etc.

What are the main types of flavonoids?

There are about 5,000 classified flavonoids, with the most important ones being those we have indicated, namely those included in the following groups (Chalcones, Flavones, Flavonols, Flavanediols, Anthocyanins, Condensed tannins, and Aurones). However, some authors and specialists prefer to classify them differently to facilitate their extraction, as well as potential medicinal uses, with the other possible classification of flavonoids as follows:

  • Citroflavonoids or citrus flavonoids come from citrus fruits and other foods such as:
    • Apples.
    • Blackberries.
    • Onions.
    • Grapes.
    • Cherries.
    • Oranges.
    • Lemons.
    • Grapefruits.
    • Broccoli.
    • Tomatoes.
    • Lettuce.
  • Rutin or rutinose (quercetin-3-rutinoside and sophorin) is a flavonoid glycoside present in foods such as:
    • Grapes.
    • Blackberries.
    • Citrus fruits.
    • Peppers.
    • Onions.
    • Red wine.
    • Apple.
    • Broccoli.
    • Tomatoes.
  • Isoflavonoids come from legumes or Leguminosae and are present in trees, perennial herbs, and shrubs. Typical foods containing isoflavonoids include:
    • Soybeans or soy.
    • Tofu.
    • Chickpeas.
    • Lentils.
    • Beans.
  • Proanthocyanidins or condensed tannins are the main pigments of plants, found in seeds and leaves. They are composed through the hydrolysis of anthocyanidins and are found in:
    • Grape seeds.
    • Red wine.
  • Anthocyanins are responsible for the red, blue, and purple color of plants as they are red pigments. They are glucosides of anthocyanidins and protect against ultraviolet radiation, insect damage, and prevent freezing of plant tissue. One must be careful with anthocyanins as they are toxic to dogs. Food with flavonoids of the anthocyanin class includes:
    • Cherries.
    • Red cabbage.
    • Red and orange peppers.
    • Blueberries.
    • Plums.
  • Catechins belong to the flavan-3-ol or Flavonol group. Their main source is the catechu plant (Terra Japonica) and also from the juice of the Mimosa catechu (Acacia catechu L.F). Foods richest in catechins include:
    • Green, black, and red tea.
    • Pears.
    • Apples.
    • Red wine.
    • Cocoa.
  • Epicatechins are phytochemicals from the Flavonol group. They are highly antioxidant and precursors of nitric oxide (NO). They increase follistatin and decrease myostatin, a protein that limits muscle growth. Foods containing epicatechins are:
    • Tea.
    • Cocoa.
  • Hesperidin corresponds to the citrus flavonoid group and plays an important role in the treatment of varicose veins, hemorrhoids, and hypertension. The foods where it is found include:
    • Oranges.
    • Lemons.
    • Grapefruits.
    • Pepper.
    • Mint.
    • Hot chili peppers.
    • Rosemary.
    • Mullein.
    • Peppers.
  • Kaempferol is a water and ethanol-soluble flavonol. It provides the scent to flowers and has antidepressant properties. It also functions as an agent in pancreatic cancer prevention. Foods with kaempferol include:
    • Apples.
    • Brussels sprouts.
    • Leeks.
    • Broccoli.
    • Radish.
    • Endives.
    • Red beets.
    • Grapefruit.
  • Cyanidins are most abundant in the fruit peel. They have anticancer effects similar to anthocyanins. It is also possible to synthesize them using the bacterium Escherichia coli. They also act as scavengers of free radicals to protect cells and cellular DNA. It is used to prevent heart problems. Foods with cyanidins include:
    • Radishes.
    • Strawberries.
    • Cherries.
    • Blackberries.
    • Dewberries.
    • Raspberries.
    • Grapes.
    • Blueberries.
    • Purple corn.
    • Apples.
    • Plums.
  • Genistein: is a flavone or isoflavone that blocks tumor development. It prevents the formation of new blood vessels and, thus, the arrival of oxygen and nutrients to tumor cells. It also acts by modulating the function of estrogens, reducing the risk of breast cancer. The foods and medicinal plants where it is found include:
    • Coffee.
    • Soy.
    • Beans.
    • Lupins.
    • Kudzu.
    • Psoralea.
    • And plants like F. macrophylla, Femingia vestita.
    • It is also possible to detect it in vitro cultures of Maackia amurensis.
  • Luteolin intervenes in carbohydrate metabolism and modulates the immune system. It is a very common flavonoid, found in foods such as the following:
    • Celery.
    • Thyme.
    • Dandelion.
    • Red clover flower.
    • Ragweed pollen.
    • Chamomile.
    • Green pepper.
    • Perilla.
    • Salvia tomentosa.
  • Silymarin has hepatoprotective effects, a quality that makes this flavonoid used in therapies against jaundice, biliary lithiasis, and in the treatment of fatty liver. Foods with Silymarin include:
    • Artichoke.
    • Milk thistle.
    • Cilantro.
    • Black cohosh.
    • Turmeric.
    • Grape skins.

Other important flavonoids include didimina and quercetin, which, along with rutin and hesperidin, are the primary citrus flavonoids.

Flavonoids in Foods

Flavonoids in foods
They are known for their antioxidant properties and as food to prevent heart disease, help against degenerative diseases, and slow down brain deterioration in old age. Foods with flavonoids are very healthy as they can help in different cases. The foods richest in flavonoids are fruits and vegetables.

Eating several servings of fruit with a high flavonoid content every day reduces the risk of heart disease and suffering from strokes. Flavonoids can be found in the following foods:

  • Blueberries.
  • Berries.
  • Plums.
  • Spinach.
  • Apples.
  • Blackberries.
  • Oranges.
  • Oranges.
  • Soy or soybeans.
  • Green and black tea.
  • Chocolate.
  • Walnuts.
  • Beer.
  • Gingko biloba.
  • Milk thistle (Silybum marianum).

The properties of foods with flavonoids protect against heart damage, improve the blood system, prevent the accumulation of LDL cholesterol in the arteries, and can have effects on blood pressure. The benefits of this type of food are so numerous that numerous specialists and health professionals recommend consuming them frequently, such as cardiologists. Many oncologists also indicate that flavonoids play a fundamental role in cancer prevention.
But besides being present in vegetables like fruits and vegetables, there are also other foods with many flavonoids such as those from cocoa, pure chocolate, and nuts. Products made from fruit like wine and soy derivatives also have a high concentration of isoflavones and flavonols.

How to Consume Foods Rich in Flavonoids

  1. Eat several pieces of fruit per day.
  2. Vary your food intake frequently.
  3. Always consume fruit raw, previously washed with plenty of water.

Studies on Flavonoids

  • Cancer Prevention Study II Nutrition Cohort.

In the medical study published under the name «Cancer Prevention Study II Nutrition Cohort» and directed by Marjorie L. McCullough, more than 98,000 people, both men and women, were monitored to understand the role of flavonoids in human health. These individuals had an average age of 70 years, and the results after several years of study were astonishing.
After grouping the study participants into categories based on the amount of flavonoids they consumed through their diet, it was found that those who had consumed more flavonoids had fewer heart attacks. The result was a 20% reduction in heart problems compared to the group that consumed the least of these secondary metabolites. It was also evident that the incidence of strokes had decreased considerably.

All these properties were isolated from other usual human conditions and toxins. Factors such as whether the participants smoked, exercised, or led a healthy or sedentary lifestyle were taken into account in the experiment.

According to McCullough himself, eating one or two pieces of fruit a day can make a difference in the risk of age-related diseases, so flavonoids are very important for maintaining a good quality of life as we age.

However, despite the extensive study and the agreement of the scientific community, there are still doubts about whether the properties and benefits of flavonoids alone are responsible for these results or whether it is also the other nutrients in fruits and vegetables that contain them.

Benefits of Flavonoids

Health-benefits-of-flavonoids
Considered as antioxidants, they play an important role in human health. The benefits of flavonoids are as follows:

  • Antioxidants.
  • For treating hypercholesterolemia or high cholesterol.
  • Cardiotonic benefits.

Much of the power of flavonoids lies in the fact that they are calorie-free, so they can be used by most people to naturally complement their diet. They are suitable for vegans, vegetarians, and lactose intolerant individuals. Flavonoids and their benefits for improving long-term quality of life must be taken into consideration. They are essential in the prevention of degenerative diseases, cardiovascular conditions, and many types of cancers.
They also help to bind certain metals such as iron and copper.

Cardiotonic Benefits

They improve the function of the cardiac muscle. Flavonoids have tonic effects on the heart, increasing blood flow and reducing wear and tear. Quercetin is the best flavonoid for heart-related diseases.
They also increase the resistance of capillaries and small blood vessels. Strokes caused by blood pressure are reduced, making it suitable to use quercetin, rutin, and hesperidin.

Hypercholesterolemia

The hypocholesterolemic properties or functions to reduce hypercholesterolemia, cholesterol levels above 240 mg per day, are well known.
Soy seems to have benefits on cholesterol due to its content of isoflavones, which produce an estrogenic and antioxidant effect, with these effects being enhanced by the other active substances that the Glycine max plant, which produces this food, contains.

Antioxidant Effects

Many of the antioxidants found in dietary supplements are precisely this type of metabolite or plant compound. The most popular antioxidant flavonoids are quercetin, catechin, anthocyanin, and isoflavone.
The antioxidant action of flavonoids protects against free radicals, atoms that lose an electron and are very reactive, traveling through the body in search of capturing the missing electron, and when they do, they destroy other stable and beneficial molecules for health.

In turn, when the free radical manages to capture the missing electron, it becomes stable, but, on the contrary, the molecule that has lost it becomes a free radical itself, continuing the chain chemical reactions.

Antioxidant flavonoids prevent these chemical reactions in the body, being capable of blocking harmful actions in living organisms.

Naturally, humans cannot produce protective chemical substances, so it is essential to include them in the daily diet to produce the antioxidant effect or protection against oxidative damage.

Properties of Flavonoids

Medicinal properties of citrus flavonoids and polyphenols
Many characteristics and medicinal effects on humans and animals have been studied. The properties of flavonoids are diverse, with notable cardioprotective and anti-inflammatory effects. However, depending on the type of flavonoid used, the benefits may be more or less potent.

Below, we explain the most important properties.

Anti-inflammatory

Thanks to the antioxidant action involved in blocking highly reactive hydroxyl and superoxide radicals, flavonoids have anti-inflammatory properties. They modify the onset of lipid peroxidation chain by altering the synthesis of eicosanoids. They also prevent platelet aggregation (possessing antithrombotic effects or reducing blood clot formation).
They also play an important role in preventing low-density lipoprotein oxidation (atheroma plaque prevention).

Antiviral

There is ample evidence from studies on the effects of flavonoids on viruses and germs. The flavonoid called quercetin is a biological flavonol with antiviral activity against the dengue virus, arboviruses of the Flavivirus genus. Phytochemicals or low molecular weight phenol molecules obtained from fruits, nuts, and roots interact with this class of viruses, reducing their damage to the infected organism.
Other flavonoids with antiviral activity include naringin, daidzein, and hesperetin.

Antiallergic

They act on the immune system and regulate the body’s response when exposed to germs and compounds that cause most current allergies. The flavonoid rutin has been used in cases of sepsis or septicemia, where the immune response to an infection can cause severe and irreparable damage as chemicals are released into the blood.

Anticancer

Numerous studies demonstrate anticancer effects when taken regularly. The properties of flavonoids to prevent cancer are linked to antimutagenic effects. They prevent harmful cell proliferation, functioning as good chemopreventive agents.
Certain in vitro studies conducted with flavonoids modulate the activity of enzymes that control the formation of carcinogenic metabolites, especially the flavonol quercetin. This has an inhibitory effect on cancer cells in the colon, ovaries, and mammary glands. It has also been proven in the gastrointestinal tract and other types of cancer such as leukemia.

Other Medicinal Properties

There are clinical trials where it has been proven that administering flavonoids decreases the production of free radicals after undergoing bypass surgery, improving recovery and preventing possible complications in the heart muscle.
Likewise, flavonoids are involved in the intracellular concentration of glutathione, decreasing the amount of glutathione by up to 50%. This contributes to the prevention of neurodegenerative and cancerous diseases in medical practice.

In addition to the indicated properties, the antioxidant effects of flavonoids help improve communication in the cells of living tissues. They stimulate gap junctions or nexus, a certain type of connection that regulates cell growth and increases the functioning of detoxification enzymes, that is, the neutralization and elimination of toxins in the body that occur naturally in metabolism.

Metabolism of Flavonoids

The main metabolic pathway of flavonoids is the liver. The second pathway by which they are metabolized is the colon.
A large portion of flavonoid metabolites is excreted in urine. The transformation of flavonoids in the liver undergoes phase I biotransformation when exposed to polar groups. The colon route or phase II is where unabsorbed flavonoids are degraded by microorganisms inside the human body. In this phase (II), conjugation with glycine, glucuronic acid, and sulfates comes into play, which, being water-soluble, will eventually be excreted in urine.

Bioflavonoids and Vitamin C

Along with the antioxidant effects of flavonoids, those of vitamin C or ascorbic acid, another potent antioxidant with properties for the skin and regulating blood circulation, are added.
Bioflavonoids and vitamin C enhance action against free radicals, increasing benefits to the body. Among the properties we can find are:

  • Protection of the skin against aging.
  • Increased synthesis of natural collagen.
  • Assistance against sagging.
  • Increased skin elasticity.
  • Effects against premature aging.
  • Improvement of bone health (bones, cartilage, and joints).
  • Promotion of new muscle tissue creation.
  • Assistance against arthritis.
  • Prevention of eye deterioration and delay of vision loss.
  • Improvement of blood circulation.
  • Beneficial effects on cholesterol.
  • Serving as a supplement for people who consume low amounts of Vitamin C or eat little fruit.
  • As an ally against bacterial infections.
  • Assistance in reducing inflammation.
  • An ideal supplement to include in weight loss efforts.

Effects of Vitamin C with Bioflavonoids

Vitamin C and bioflavonoids, properties and benefits for peopleBoth are very potent antioxidants, enhancing their properties when taken together. The synergistic effect benefits both, greatly benefiting the body.
Bioflavonoids and vitamin C protect against oxidative stress, safeguarding cells from damage caused by free radicals.

At the same time, they are also a source of health against the damage caused by sunlight or the harmful effects of tobacco on the skin.

Regarding the use of vitamin C and flavonoids for weight loss, it is beneficial because when dieting, many more free radicals are generated as adipose tissue breaks down. The antioxidants called bioflavonoids inhibit the damage they cause to the body, preventing skin aging and promoting greater elasticity by stimulating collagen synthesis.

Medications with Flavonoids

There are different drugs and medicinal preparations that include antioxidants to treat pathologies and facilitate healing after surgeries. One of the best-known medications containing flavonoids is Daflon, although there are also others widely used such as Dipemina, Venartel, and Bioxine.
Each of these medications has a dosage and mechanism of action, being indicated for treating venolymphatic insufficiency or the so-called «heavy leg syndrome» as well as «restless legs syndrome» in the case of Daflon.

In the case of Venartel, it is indicated as a vasculoprotector and venotonic. Depending on the composition of these drugs that include micronized flavonoids and other active ingredients, their use and administration will differ as well as their medicinal properties.

All this shows how flavonoid antioxidants are actually beneficial when used at appropriate times, meeting the needs and demands of many people for the treatment of various pathologies.

Of course, since these are medications, they should always be prescribed and indicated by a doctor, which is different from what happens with products labeled as dietary supplements that can be purchased without a prescription and although it is always advisable to take them when a healthcare professional indicates it, in this case, a prescription will not be necessary as it is with those regulated as flavonoid medications.

The use of flavonoids is very useful as an adjuvant since it enhances the effects of other substances that serve as health therapies.

Citrus Flavonoids

They are derived from citrus fruits such as lemon, orange, or grapefruit. Citrus flavonoids are suitable for vegans and have properties similar to others. To determine their benefits, it is necessary to check which type of flavonoid we are buying, that is, whether it is quercetin, neohesperidin, rutin, nobiletin, diosmetin, eriocitrin, or tangeretin.
Depending on the citrus bioflavonoids or flavonoids from citrus fruits such as those from grape seeds, they can be used for various conditions as well as to enhance the antioxidant effect and delay aging.

The most common citrus fruits from which flavonoids are obtained include:

  • Acerola.
  • Plum.
  • Blackberry.
  • Citron.
  • Cupuaçu.
  • Peach.
  • Raspberry.
  • Strawberries.
  • Pomegranate.
  • Gooseberry.
  • Jabuticaba.
  • Orange.
  • Mandarin.
  • Lime.
  • Lemon.
  • Quince.
  • Loquat.
  • Pineapple.
  • Tamarind.
  • Tomato.
  • Grape.

There are many brands of citrus flavonoids, each of which includes a series of polyphenols and natural pigments that will benefit in specific cases by using acidic or semi-acidic fruits such as apples, guavas, pears, or persimmons.

Oral Flavonoids

As the name suggests, oral flavonoids are those taken by mouth, ingested in pills or gelatin-coated capsules.
This type of flavonoid can be derived from many sources, and its composition can also vary. The only difference from the other classified types is their commercial presentation. In most cases, oral flavonoids are available as dietary supplements, although in the case of medications, they may also fall into this classification if their ingestion is necessary.

PPT Flavonoids

These are indicated to modify the blood’s ability to coagulate. PPT flavonoids (Partial Thromboplastin Time) are suitable if there are coagulation problems, thrombosis, and cases of phlebitis.
Their effects act on the plasma protein called prothrombin. This is part of the blood coagulation process and also reacts with the enzyme thromboplastin, located inside the thrombocytes.

Flavonoids for Hemorrhoids

This type of disorder is very common in the Western world because many jobs are sedentary and require spending many hours sitting in front of a computer or in an office chair.
Flavonoids for hemorrhoids, also known as phlebotonics, are helpful against benign anorectal diseases also known as piles. Common symptoms include itching, burning, swelling, and bleeding.

Using a flavonoid as an aid can strengthen the vascular walls and increase venous tone, improving capillary permeability and regulating lymphatic drainage from the external area of the rectum. It is quite common to find remedies for hemorrhoids with flavonoids, centella asiatica, and ruscus, as all these ingredients improve venous flow and have vasoprotective properties.

Flavonoids in Chocolate and Cocoa

Chocolate and cacao

In cocoa-derived foods, we can also find polyphenols and plant secondary metabolites. Flavonoids in chocolate are beneficial when consumed moderately over a period of two weeks.

Cocoa, being a natural plant-derived product, carries a high percentage of epicatechin, a flavonoid with effects on blood vessel dilation. As indicated by Mary Engler, a professor at the School of Nursing at the University of California in San Francisco (USA), and director of the study published in the Journal of the American College of Nutrition.

Catechin and epicatechin are polyphenolic antioxidants of the flavan-3-ol or flavonol subgroup, also present in the Terra Japonica or catechu plant. Cocoa flavonoids can also be consumed by ingesting juice from Mimosa catechu or Acacia catechu L.f.

It is also noted that chocolate antioxidants reduce the oxidation of LDL cholesterol or «bad cholesterol,» providing benefits for the cardiovascular system and inhibiting platelet aggregation. After several days of consumption, there is a lower risk of blood clots and cardiovascular accidents, heart attacks, and strokes.

Flavonoids in Wine

Flavonoids and polyphenol antioxidants in red and white wine

The concentration of polyphenolic compounds in wine varies among different types of this beverage, with flavonoid values in wine ranging from 1.06 to 1.8 g/L.

White wine has a lower amount of antioxidants, at 0.16 g/L, while the flavonoids in red wine are approximately 0.30 g/L. There are slight variations depending on the brand and vintage of the wine.

The composition and quantity of polyphenols or bioflavonoids largely depend on the type of grape used, cultivation methods, climate, terrain, and fermentation procedures.

The flavonoids present in wine include:

  • Resveratrol.
  • Quercetin.
  • Catechin.
  • Epicatechin.
  • Procyanidins.
  • Rutin.

Phenolic compounds such as coumarinic, caffeic, ferulic, cinnamic, vanillic, and gentisic acids can also be found. All of these are synthesized through the phenylalanine metabolic pathway.

Like other flavonoid-rich foods, wine has a strong antioxidant effect. It prevents the oxidation of LDL cholesterol and prevents diseases such as atherosclerosis, cancer, and cardiovascular diseases. The beneficial properties of wine are due to the reduction of LDL lipid peroxidation, either by blocking free radicals, chelating transition metals, or enhancing the utility of vitamin E and carotenoids.

People who do not wish to consume alcohol but still want to benefit from the properties of wine can consume grape juice or grape juice, which, although containing fewer flavonoid antioxidants, avoids the side effects of alcoholic beverages.

Flavonoids for Varicose Veins

Flavonoids of the Hesperidin type are used for the treatment of chronic venous insufficiency and other conditions such as varicose dermatitis, varicophlebitis, lymphedema, varicose ulcers, and vascular retinal disorders.

Flavonoids for varicose veins reduce the inflammatory process and are included in drugs such as Diosmin. Hesperidin is a flavone and therefore belongs to the group of flavonoids we are discussing in this article. This group of plant secondary metabolites has anti-inflammatory activity that can be used in perivenous and proinflammatory disorders.

Hesperidin for varicose veins has venotonic, phlebotic, anti-varicose, and vasculoprotective properties. Its chemical structure allows the mechanism of action to function on microcirculation, improving permeability and increasing the resistance of blood vessels. It also protects the vascular endothelium and has antiplatelet (coagulation-modifying) and analgesic effects.

Side Effects of Flavonoids

  • Hypersensitivity.
  • Allergy.
  • Headache.
  • Flush.
  • Diarrhea.
  • Dyspepsia.
  • Nausea.
  • Vomiting.
  • Colitis.

Contraindications

  • Hypersensitivity to the active ingredient or excipients contained.

It is common for discomfort or adverse reactions to disappear after discontinuing flavonoid treatment. If you have any doubts about the side effects of flavonoids and their contraindications, consult a specialist who can advise you in your specific case.

Are Flavonoids Natural?

As we have been developing and explaining throughout this article on «what are flavonoids and what are their properties and benefits,» we can consider them natural.

Their origin is plant-based, being extracted from various plants such as citrus fruits and other plant species such as vegetables, seeds, and products derived from these.

So yes, we can assert that flavonoids are natural.

Soy or Soybean Flavonoids

Flavonoids of soy or soybean, plant Glycine max

Soy contains isoflavones, a class of flavonoids very similar to human estrogens. They are considered phytoestrogens, non-steroidal chemical compounds from plants that function very similarly within the body due to the similarity in their chemical structure.

Soy flavonoids are widely used as a natural remedy and as an alternative to hormones to treat menopausal symptoms. Also, like other polyphenolic compounds, they have antioxidant effects, protecting cardiovascular health and helping to alleviate menopausal hot flashes.

While soy flavonoids can help women reaching perimenopause or the stage of fertility loss, they are not a substitute for estrogen therapy. They can help counteract some menopausal side effects, but proper treatment is always necessary, especially when there is bone loss, vaginal dryness, and lack of sleep.

Differences Between Flavonoids, Polyphenols, and Tannins

Polyphenols can be divided into 3 subclasses:

  • Tannins.
  • Lignins.
  • Flavonoids.

All these classes of polyphenols are secondary metabolites of plants from the shikimic acid pathway. These phenolic compounds oxidize very quickly, much faster than other substances, a quality that gives them protective properties against oxidation caused by free radicals.

Tannins react with collagen proteins. They are widely used to tan raw animal skins as they contain many collagenous structures. Upon contact with tannins, they bind and increase the resistance of the skin against wear, heat, humidity, natural decay, and attacks from microorganisms that feed on biological matter.

Flavonoids are also phenolic compounds, so they are within the group of polyphenols. There are 6 main classes, and they can mostly be found in the leaves, flowers, and fruits of plants and trees. Their function is to protect plants from sunlight and from the attack of insects and microorganisms. In the human body, they act as antioxidants.

Uses of Flavonoids in Cosmetics

Due to their antioxidant and anti-inflammatory properties, flavonoids are widely used compounds in the production of anti-aging creams and beauty treatments. Flavonoids in cosmetics have been used for many years, improving cosmetic formulations and enhancing their benefits for the skin.

It is common to find ingredients such as isoflavones, quercetin, and anthocyanins in anti-wrinkle creams and anti-aging serums. These types of creams protect against sun damage and slow down aging, allowing other ingredients such as hyaluronic acid, vitamin C, and collagen to function normally.

How to Take Them? How Should Flavonoids Be Taken?

The method of administration may vary depending on the type of disorder being treated or if they are ingested as a dietary supplement. It is also important to remember that they can be used as a medical treatment, in which case the dosage and administration period should be determined by the doctor.

However, as mentioned earlier, it is common to take flavonoids to reinforce antioxidant action, in which case they should be taken as follows:

  1. Take 1 or 2 capsules per day with a glass of water.

As you can see, the way to take flavonoids is very simple and practical. Simply ingest 1 or 2 capsules each day (check the instructions on the packaging and from the manufacturer) to block the damage caused by free radicals. They can also be taken through food, in which case there are no specific instructions for use. Simply eat the food as you would with any other.

With this, in addition to protecting the cardiovascular system and fighting inflammation, we can delay the appearance of wrinkles on the skin and improve blood function.


References:

  • Grosso G1, Galvano F, Mistretta A, Marventano S, Nolfo F, Calabrese G, Buscemi S, Drago F, Veronesi U, Scuderi A. Red orange: experimental models and epidemiological evidence of its benefits on human health. Oxid Med Cell Longev. 2013;2013:157240.
  • Sam-Long H, Ping-Hsiao S, and Gow-Chin Y. Effects of Citrus Flavonoids. Journal of Agricultural and Food Chemistry: Neuroprotective. J. Agric. Food Chem., 2012, 60 (4), pp 877–885.
  • Kumar A, Dogra S, Prakash A. Protective effect of naringin, a citrus flavonoid, against colchicine-induced cognitive dysfunction and oxidative damage in rats. J Med Food. 2010 Aug;13(4):976-84.
  • Wesołowska O, Wiśniewski J, Proda-Pomianek K, Bielawska-Pohl A et al. Multidrug Resistance Reversal and Apoptosis Induction in Human Colon Cancer Cells by Some Flavonoids Present in Citrus Plants J. Nat. Prod., 2012, 75 (11), pp 1896–1902.
  • Perera N, Liolitsa D, Iype S, Croxford A, Yassin M, Lang P, Ukaegbu O, van Issum C. Flebotónicos para las hemorroides, 15 agosto 2012. Cochrane.
  • Rizza S, Muniyappa R, Iantorno M, Kim JA, Chen H, Pullikotil P, Senese N, Tesauro M, Lauro D, Cardillo C, Quon MJ. Citrus polyphenol hesperidin stimulates production of nitric oxide in endothelial cells while improving endothelial function and reducing inflammatory markers in patients with metabolic syndrome. J Clin Endocrinol Metab. 2011 May;96(5):E782-92.
  • El chocolate puro rico en flavonoides mejora la circulación sanguínea, 16 de noviembre de 2004, periódico elpais.com.
  • Joan Aragone on June. Small daily doses of flavonoid- rich chocolate improve blood vessel function, study suggests 01, 2004.

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