ABOUT FLAVONOIDS, ANTIOXIDANTS, THEIR EFFECTS AND PREBIOTICS

The flavonoids are substances produced by plants in order to provide protection to their cells from particularly harmful UV rays and other plant pathogens. These materials can be useful to human beings, since they play similar protective functions in the human body, and thus their consumption may protect the body from harm.

Flavonoids have a number of positive features, among which the most significant are their antioxidant effects. With this help they provide enhanced protection against especially harmful reactions and free radical reactions in the body. The flavonoids and other dietary antioxidants can enhance the physiological effects of vitamin E and vitamin C because they synergize with them and help their regeneration. All plants produce flavonoids, but their structure and nature is very diverse. There are compounds that are specific to only certain plant families, while others are commonly found in all plants.

We currently know the structure of 6000 flavonoids, but only know the occurrence and precise compound amounts of a few. The most significant flavonoid sources are berries, green leafy vegetables and onions. We now know that the consumption of plant foods that contain flavonoids has illness prevention and health maintaining effects. Curative effect of only a few, are major components of medicinal products containing flavonoids, in which the amount of flavonoids was significantly greater than the quantity of food consumed, and thus their use for medical monitoring. Only a few types of medicine’s active ingredients are flavonoids (contain a higher amount than otherwise found in food) and because of consulting with a doctor containing their use is recommended. The consumption of flavonoids naturally found in foods does not pose a risk. On the contrary, it helps the body maintain the balanced relationship between our immune system and harmful agents in a healthy body.

Prebiotics are special carbohydrates that can be digested neither by the enzymes of the mouth, stomach nor the small intestines. Because of this they enter the large intestines undigested where they only provide nourishment for the helpful probiotics while being of no use to harmful microbes. This gives the probiotics a chance to reproduce and reach a high number. In essence the prebiotics belong to the family of the highly praised dietary fibers. Their uniqueness lies in the fact that in contrast to the tree-like fiber and the cellulose based fruits and vegetables they are water soluble and thus enter the large intestines in a gentle way and can be accessed by the probiotics easier.

FREE RADICAL REACTIONS, PROTECTION AGAINST THEM AND THE PROPERTIES OF FLAVONOIDS.

The free radical reactions and oxidative stress processes in the body have been the focus of interest for a long time.

In particular, special attention is paid to natural sources of antioxidants which are able to prevent some diseases that are associated with the formation of oxidative degradation. Simply put they help in maintaining health.

It is well known that without oxygen and light, life would not have been evolved on our planet. These two elements are essential for all living beings on our planet. Nevertheless their toxic effects should not be neglected. First, under some circumstances the oxygen found in air oxidizes biomolecules and changes their structure dramatically. Second, 4% of ultraviolet light carries amounts of energy that can tear covalent bonds. These effects in combination with other agents can initiate serious damage to biomolecules.

THE SIGNIFICANCE OF FREE RADICAL REACTIONS

Free radicals are molecules or molecule particles which contain unpaired electrons in their outermost electron shells. Since the electrons tend to form pairs, the molecules that contain lone electrons molecules intensively look for other molecules from which they can steal electrons. Thus free radicals easily and quickly react with other chemical compounds. Free radicals occur in living beings under normal circumstances. Their roles are clearly defined. Nature has given them multi-level protection. The external environment also generates free radicals, for example through the energy consumption taken from oxygen, other molecules, ultraviolet radiation, heat, and the effect of various chemicals. Certain medicines as well as agricultural chemical agents, anesthetics, industrial solvents and tobacco smoke are sources of free radicals. The presence of free radicals in our environment affect the biochemical processes of the body through consumption of food, inhalation and through our skin. Our immune system has a high level of protection against free radicals and is able to keep them from doing damage up to a great degree. Free radical reactions that escape the grasp of the immune system can damage biomolecules and cause illnesses such as heart and vascular disease and the growth of tumors.

Free radicals first attack the amino acids that make up fat molecules because their double bonds are very sensitive to oxidation damage. This radical based chain reaction is called lipid peroxidation. As a result of their tendency to cause chain reactions even a very small number of free radicals can cause severe damage. The initiation process is triggered by an external or internal agent (UV-light, active enzymes in physiological processes, transition metal ions such as Fe21). In this process free radicals with relatively simple and small molecular structures (for example hydroxyl or superoxide radicals) are composed.

The second stage of propagation, the former involves much more intensive process, because the first stage generated free radicals (superoxide, hydroxyl) in the joining of two unsaturated fatty acids react with a new record, an increased number of free radicals (lipid hydrogen peroxides) generation. The second step is propagation. It is more intensive than the initiation period because at this stage the free radicals that were generated (superoxide, hydroxyl) react with unsaturated fats and generate a large number of free radicals called lipid hydroperoxides. The process ends with the generation of non-radical substances for example aldehydes. Besides generating byproducts such as aldehydes and ketons the process also frees up molecules that directly react to fats, proteins and DNA.They can also change the molecular structure of foods making them damaging to health.

The most well known of these reactions is oxidation and the spoiling of food that comes with change in color, smell and taste. Aldehydes and ketons for example are responsible for bad the bad taste of food. Oxidation on the other hand doesn’t only change the structure of fat cells but also damages other molecules such as vitamins and proteins that make up amino acids. This makes the nutritional value of food much less than normal.

The most well known oxidation process in food is rancidity. This process involves changes in taste, color and smell. During the process different chemical reactions produce byproducts that are damaging to health. These byproducts include aldehydes and ketones, which are responsible for the unpleasant taste of spoiled food. However oxidation doesn’t only affect the structure of fatty acids. It also impairs other molecules like vitamins and amino acids that make up proteins. Because of this the nutritional value of food is significantly reduced.

Some free radicals arise normally in our bodies and play an important role in maintaining our body’s normal state. Some cells, for example produce free radicals that attack and destroy pathogens that enter our body. In some free radical and lipid oxidation processes our body brings about chemical reactions that are essential to keeping its balance (for example substances that control blood pressure, gore and hormones). Our body can neutralize large amounts of free radicals that are produced under natural circumstances. In the case that the internal free radical producing processes are disturbed by pathogens or an increased external load of free radicals (smoking, drugs, UV rays, poor or unbalanced diet!) and too many free radicals are present, our body’s immune system cannot protect itself against them. Thus the change in the body’s critical molecular structure causes disturbances in its biochemical processes. By modifying these physiological processes it leads to illness.

Medical science has confirmed that free radicals are present during stages of illness. These include in particular cardiovascular diseases, for example of atherosclerosis, cancer diseases, eye, joint and neurological abnormalities may be noted. Antioxidant defense is the main protective mechanism against oxidation in the living body.

A general definition of an antioxidant is a molecule which is present in low concentration compared to material that can oxidize. By this it slows down or entirely stops the oxidation process. The potency of so-called antioxidants is defined in terms of induction time. The more effective an antioxidant is, the longer the induction period and the later the oxidation of the attacked molecule.

In terms of mechanisms of effect antioxidants can be of primary or secondary nature. The primary or chain-breaking antioxidants are compounds that can neutralize lipid free radicals by the transfer of hydrogen and changing them into less reactive compounds. These relatively stable compounds are no longer able to participate in the propagation of lipid peroxidation thus interrupting the chain reaction. The primary antioxidants are effective in the induction period by delaying the oxidation process. The primary antioxidants are phenolic molecules, tocopherols (compounds with vitamin E- like effects), gallic acid and its derivatives, flavonoids and other components.The secondary or preventive antioxidants prevent the oxidation of lipids in a different way. They either inhibit the initiation phase (the first step of lipid peroxidation) by oxidizing instead of the lipid molecules, or transform the products of the oxidation processes into non-toxic material during or after the chemical reaction phase by way of a process called reduction. Natural antioxidants such as phospholipids and citric acid belong to this category and they synergize with primary antioxidants.

The essential characteristic of antioxidants is that most of them can inhibit the oxidation process through multiple mechanisms of action and can act in synergy with each other. The synergism in this case means that two or more combined molecules that are side by side have a greater effect than if the same amount of molecules were working separately. This phenomenon is due to the following: when the antioxidant molecule prevents the oxidation of the target compound its chemical structure changes. In order for it to protect the next target molecule it has to change back to its original form. This will where the other antioxidants come in to help. Some antioxidants protect the target molecule and others help other antioxidants change back to their original form. If there are a lot of antioxidant molecules in a system, then there is always a molecule available for filling the specific function needed. Thus certain antioxidants are able to strengthen the effects others.

Antioxidant protection against free radicals consists of mechanisms made up of enzymatic and non-enzymatic elements. Some of these elements (vitamins, flavonoids) are synthesized by plants and our bodies can only get them through diet while others (enzymes, glucose, uric acid) can be produced by our bodies. Enzymes are protein-type molecules. Enzymes are catalysts in most chemical and biochemical processes in bodies of living organisms.

The primary characteristics of these biological catalysts are that they enable the meeting of reactive compounds.They ensure optimal location for the compounds so they can react to one another. In living organisms, chemical reactions cannot take place without enzymes. A characteristic of enzymes is that they do not go through any changes during these reactions. The best-known members of the antioxidant defense system are catalase, glutathione peroxidase and superoxide dismutase enzymes, which transform a variety of free radicals. Molecules that get rid of toxic substances from our body and biomolecules, namely enzymes that repair DNA structures are also important members of our self defense mechanism. The small molecule antioxidants include the well-known Vitamins C, E and A and the latter’s pro-vitamin A, the J3-carotene. Most people are aware of the fact that we can get these vitamins from eating plants except for vitamin A which we get from eating meat. In addition to vitamins other types of molecules can also act as antioxidants. These include falvonoids, phenolic acids and their isoflavon derivitives, fitin acids, certain sulfurous amino acids, reduced glutathione, selenium, in certain circumstances glucose, uric acid, bilirubin, ubiquinone (QIO) and liponic acid. Since some of these compounds are found in fruit and vegetables the consumption of these foods significantly contribute to keeping our body’s pro-oxidant/antioxidant levels in balance. Pro-oxidants like the previously mentioned free radicals are compounds that cause the oxidation of molecules.

THE SOURCE OF ANTIOXIDANT VITAMINS

VITAMIN E:

• vegetable oils, cold pressed oils from oilseeds
• vegetables, fruits
• beef, poultry, fish

VITAMIN C:

• fruit: citrus fruits, strawberries, rosehips
• vegetables: tomatoes, green leafy vegetables, pickled cabbage

KAROTONOIDS:

• ß-carotene: yellow-orange vegetables and fruits, dark green leafy vegetables

Vegetables

• ß-carotene: carrots
• Lycopene: tomatoes
• lutein, zeaxanthin: dark green leafy vegetables
• ß-cryptoxanthin: citrus

VITAMIN A:

• chicken, beef, pork and foie gras, preparations of liver, fatty cheeses, egg yolks, cream

Ascorbic acid (vitamin C) is a water soluble vitamin that plays a primary antioxidant role by protecting the membranes that separate cells and lipids from the harmful effects of free radicals. They are able to capture a high number of free radicals. Ascorbic acid is in a synergic relationship with vitamin E and is able to regenerate it. It inhibits the effects of oxidation agents in tobacco smoke.

Tocopherols (vitamin E-active substances) are the most important lipid-phase antioxidants. Tocopherol compounds have the following characteristics: Side-chains found in their molecules are fat soluble while their ring structured parts are water soluble. This way they can have antioxidant effects on both water and fat soluble molecules. One tocopherol molecule is capable of protecting thousands of lipid molecules from oxidation.

The addition to ascorbic acid, cysteine, and reduced glutathione can also regenerate some of the tocopherol compounds.

Out of the carotenoids beta-carotene is the one we usually hear about, mainly because of its provitamin effect and its frequency. Provitamin effect means that, under appropriate conditions vitamin A is produced from it, however, this process takes place only in animals, so we can only get it from eating meat. The plants, however, occur in very large numbers of other carotenoids (ex: lycopene, lutein, zeaxanthin), which also have significant antioxidant effect. On the other hand a high number of karotinoids are found in plants. They have significant antioxidant effects. Karotinoids have mainly primary antioxidant effects.

A number of studies have been made concerning the consumption of antioxidant vitamins and their connection to cardiovascular diseases and cancer. In these studies scientists also looked at the frequency of the presence of cancer and other illnesses that cause death. These observations can be briefly summarized by the following:

Out of the antioxidants vitamin C deficiency causes damage to the circulatory system and the growth of tumors while its antioxidant role is mainly in the regeneration of carotene and tocopherol. The daily requirement for consuming vitamin C is 60 mg. Any excess amount is unnecessary. Vitamin E plays a primary role in the prevention of cardiovascular disease. Due to its side effects (increased bleeding) the daily need of tocopherol (12mg) in not recommended for healthy people. A daily intake of Carotenoids (6 mg / 3-carotene) is useful for the prevention of both cardiovascular disease and cancer.

Prophylactic use of higher-dose application of the literature, however, is considered. As a preventative action the intake of a higher dosage can be considered. According to tests up to this day the intake of antioxidants in combination has been proven to be more effective than separately. This is because the antioxidants, more specifically the vitamins form a mutual complementary system. This system’s best form is by eating the fruit, vegetables themselves. By consuming high-doses of antioxidants by themselves instead of getting benefits we can get contrary effects. Although thourough research about plant based polyphenols and the roles of flavonoids, their physiological effects and chemical structure has been made in the past 40 years, their effects on the human body are yet to be fully discovered. The flavonoids in foods are non-nutrient components meaning that they have no nutritional value for the human body. Szent-Györgyi and his colleagues in 1936 showed that two types of flavonoids (routine, naringenin) derived from citrus fruit reduce capillary fragility and permeability. Because of this he named the flavonoids vitamin P (P for permeability) and vitamin C2 because numerous flavonoids can stabilize vitamin C. Later on the theory of flavonoids as vitamins was discarded because in the absence of vitamins the body can’t function while the same has not been proven for flavonoids.

THE CHEMICAL STRUCTURE OF FLAVONOIDS AND THEIR OCCURRENCE:

Flavonoids have a C6-C3-C6 carbon console. The two benzene rings (A and B) are connected through a heterocyclic ring that contains an oxygen atom (figure 2). Presently scientists have identified 6000 kinds of differently structured flavonoids. Sugar molecules attach to the above mentioned consoles (aglicons) and bring about glucosoids that are found more frequently in nature than aglicons…

By the term flavonoids we are talking about 13 chemical compounds that only differ in their side-bonded groups and their placements as well as the difference between the presence or absence of double C2-C3 carbon atom bonds. According to present day research certain compounds like flavoneones, flavones, flavonols, flavoneones, anthocyanins, and isoflavones play important roles in protecting health while others like aurons, chalcones and coumarins are less important. Within the flavonoid subgroups an even larger variety of chemical structures can be observed.

FLAVONOIDS ARE SECONDARY BYPRODUCTS OF PLANT PHYSIOLOGICAL PROCESSES.

Plants produce these molecules for their own defense.

Their functions in plants are:

• pigmentation of plants
• protection against UV light rays, damaging free radicals, microorganisms and other pests, fungi etc.
• participation in biochemical processes (ex. modifying the function of enzymes).
• Natural coloring and taste components in foods.
• Flavonoids are light yellow or milky-white in color.
• Some colors are only visible to the insects that are able to see UV light.

FLAVONEONES

• The main source of flavoneones are citrus fruits and juices made from them.
• The flavoneones play a significant role in creating their taste.
• Neohesperids such as naringin in grapefruit are bitter while rutinozoids such as hesperidin in oranges have no taste.
• Chickpeas, cumin, hawthorn, liquorice, black pepper and berries also contain flavanones.
• Hesperidin is found in cumin and black pepper. Narirutin and naringenin are found in hathorn and sorb.

FLAVONES

Flavones play a role in shaping the color of plant tissues in places they are present in high concentrations. However they also shape the taste of edible parts of plants. Citrus flavones such as nobiletine, sinesetine and tangeretine are flavones that give the citrus fruits their bitter taste. At the same time foifoline and neodiosmine decrease the bitter taste of substances (ex. quinine, caffeine, saccharin). Falvones are present mostly in cereals, medical herbs/spices (rosemary, thyme) and vegetables. The most well known flavones are pigenine and luteoline. Apigenine is found only in spinach, luteoline is found cereals and vegetable leafs. Pigenine has also been found in pollen collected by bees.

FLAVONOLS

Most plants synthesize flavonols out of which quercetin and kempherol are the most well known. Quercetin is generally present in the leaves and fruit of plants. Kempherol is also very common in fruits, roots, leafy greens, spices and legumes. Isoarmentin is found in peas and onions, miricetine is found in berries, corn and tea. Flavonols are primarily concentrated in shells of fruit.

ANTHOCYANINS – ANTHOCYANIDS

Anthocyanins most commonly occur as a mixture of structurally diverse compounds. They are found in elderberry, blackberry, cherry, grapes etc. Cherries, plums, eggplants, red cabbage, radish and beetroot get their blue-reddish color from them. Delfmidin, cianidin, petunidin, peonin and malvinidin are found in blue grape juice. Anthocyanins form complexes with metal ions (iron, magnesium). They are present in flower pedals and get their names from the names of the flowers they were isolated from. The color of anthocyanins highly depends on the PH of the environment. In an acidic environment they are usually red, in a neutral environment they have no color, and in a basic (alkaline) environment they are blue. The anthocyanin content of fruit increases with the process of ripening. Anthocyanins are found in cereals, roots and leafy greens in small quantities but their primary source is in fruit. In apples, pears and nuts they are found primarily in the shell. They are present in all parts of sorbs and cherries. Red beans, red cabbage, radishes, purple onions and rhubarb are a high source of anthocyanins. The anthocyanins are often used in the food industry for food coloring.

FLAVONES

Concerning their structure and names flavones are the most complex of the flavonoid compounds. Their names used in literature are pretty diverse: cathecins, leukoantocianins, proantocianidines, tannins. These compounds can be identified as mono, bi, tri and poly flavones. This means the linkage of one, two, or more simple structured molecules. Mono flavones like catechin and epicatehin are found in ripe plants and tiatal leafs. Bi and tri flavones are found in apples, black currants, blackberries, blueberries, grapes, peaches, strawberries and cereals (sorghum, barley). Green and black teas are the most significant sources of flavones because they contain high amounts of catechin, epicathec, galla and other compounds. Chocolate and cocoa are also good sources of flavones.

ISOFLAVONES

Nowadays special isoflavones have gotten a lot of attention due to their connection with estrogen (female hormone). Due to the orientation of their B ring their structure differs from the previously mentioned compounds. The most well known isoflavones are daidzein, genistein, biochanin A and formononetin. Isoflavones are almost exclusively found in legumes. Soybeans and soy products are the most significant sources of isoflavones but they are also present in dry peas, alfalfa, clover sprouts, green peas, chick peas, lima beans and sunflower seeds.

Flavonoids are found in nearly all plant foods in concentration amounts ranging from nano-grams/kg to g/kg. The table below shows a range of dietary plants and their polyphenol and flavonoid content.

Food	Flavones and flavonols (mg / kg)					Total polyphenol (g/kg, g/l)
Quercetin	Kempferol	Apigenin	Luteolin	Miricetin
Onion	284-486	24.3	nd	nd	nd	0,1-20,3
Leek	5.0	11-56	nd	nd	nd	0,2-0,4
Celery leaf	nd	nd	248	111.4	43.4	0,94
Brussel sprouts	nd	7.4-12.8	nd	6.7	nd	0,06-0,15
Broccoli	15.4-30	30.8-72	nd	nd	nd	-
Red cabbage	1.9-9.2	nd	nd	6.3	nd	-
Green beans	32-45	8.8-14	nd	nd	nd	0,34-2,8
Spinach	272,2	nd	nd	66.4	nd	-
Potato	4.6-11	nd	nd	nd	nd	-
Radish	nd	10.5-21.1	nd	nd	nd	-
Peppers	9.4	nd	nd	7.0-14	nd	-
Tomato	2.7	8.4	nd	nd	nd	0,85-1,3
Turnip	3.2	22.7	154.0	nd	85.4	-
Salad	16.3	nd	nd	nd	nd	-
Sorghum	-	-	-	-	-	1,7-102,6
Barley	-	-	-	-	-	12,0-15,0
Apple	7.7-40	2.0-16	nd	nd	nd	0,27-2,9
Black currant	13	nd	nd	nd	nd	1,4-12,0
Bilberry	-	-	-	-	-	1,3-2,8
Cherry	8.9	nd	nd	nd	nd	0,6-0,9
Grape	15.0-38.7	nd	nd	nd	4.5	0,5-4,9
Raspberry	6.0-9.7	5.0-12.0	nd	nd	990	0,38-2,2
Walnut	nd	nd	nd	nd	4560	-
Hops	500-1200	-	-	-	-	-
Beer	-	-	-	-	-	0,3-0,6
Red wine	8.3	nd	nd	nd	7.9	1,8-4,0
Chocolate (milk/dark)	-	-	-	-	-	9,9/23,4
nd – not measured component

There are flavonoid compounds and compound families that are generally present in all dietary plants. Flavonol is an example of such compounds as well as rutin and quercetin that are present in most plants. Other compounds are only present in certain types of plants. Anthocyanins are a good example of this. They are exclusively present in soft fruits and purple vegetables. Most fruit, vegetable juices and teas contain certain amounts of flavonoids and polyphenol compounds. For example beer, wine and tea get their distinctive tastes from different biflavones. Concerning vegetables according to our own research and data from other literary sources onions, parsley, spinach, celery and different varieties of lentils are the richest sources of flavonoids.

Out of fruit strawberries, blackberries, raspberries, black currants and blueberries are the richest sources of flavonoids. Out of oily nuts walnuts have the most amounts of flavonoids.Fruit and vegetables lose a great deal of their flavonoid content during cooking and the peeling. Although flavonoids are relatively stable compounds that are not sensitive to heat, oxygen and a slight change in pH, modern cooking methods cause their degeneration due to loosening their bonds. On average food loses 50% of its flavonoid content due to cooking and food processing. Flavonoids and compounds that contain polyphenols are responsible for the darkening and brown spots that come about in fruits and vegetables during food processing. Fruit juice production, especially production of citrus fruits can increase the flavonoid content of the product since the flavonoids are extracted from the peels. Substantial amounts of flavonoids remain intact during the preparation of apple, peach, apricot, plum, orange and strawberry jam/jelly. During traditional juicing processes of apples (simple pulping and enzymatic extraction) 80% out of quercetin’s glucosoids stay in the press chamber. The juice itself ends up with only 10%.

FLAVONOIDS IN MEDICINE

A large proportion of natural medical products contain flavonoids. Switzerland and France have over 100 medical products that contain flavonoids. Natural therapeutic methods and illness prevention is gaining popularity in our country. Due to this there has been an increase in the production and sales of natural dietary supplements and medicines that have flavonoids as active ingredients. Products with rutin and diosmin as active ingredients (ex. Detralex contains diosmin and hesperidin, Rutascorbin contains rutin and ascorbic acid) are currently on the market. They are used for increasing the tone of blood vessels and the strengthening of the capillaries. Medicines like Silibinin and Legalon contain milk thistle (Silibum marianum). Milk thistle is well known to have liver protecting properties. Vaccimun (blackberry) and Ribes (black currants) are types of berries that improve vision and increase capillary resistance. Basil, mint, oregano, rosemary, sage and thyme belong to the Labiatae family and are considered traditional medicines in most countries.

CHEMICAL-BIOCHEMICAL PROPERTIES

Given the large number of polyphenols compounds in foods, the body consumes a significant quantity of these compounds on a daily basis. Most of these compounds are flavonoids. Flavonoids have an ability to perform a wide range of chemical and biological activities. They have antioxidant effects, can neutralize free radicals, can bind metal ions in complex compound form and can modify the functions of enzymes within a wide range of cells. The above mentioned effects are achieved by polyphenol based compounds in collaboration with tocopherols and vitamin E, C. These effects are achieved through synergy and are very powerful health enhancing functions.The biological effects of flavonoids have been studied in several test systems. A wide range of effects have been proven either fully or partially.

In the beginning research concerning flavonoids was mainly conducted in test tubes and not in living organisms. During the past 5 years however, tests have been conducted in living bodies of humans and animals. Studies suggest that the positive effects of flavonoids can be grouped by the following biochemical processes:

1. Antioxidant activity (according to the previously described mechanisms) and / or free radical trapping
2. Role they play on the functioning of the immune system and anti-inflammatory effects
3. Anti-allergic and asthma healing properties
4. Modifying effects on the function of enzymes, usually inhibition of their functioning
5. Anti-virus and anti-microbial effect
6. Isoflavonoidic effects with characteristics of only having effects on estrogen/anti-estrogen.
7. Mutation prevention effects in DNA
8. Cancer-related processes primarily preventative processes.
9. Liver protecting properties
10. Effects on blood vessels, primarily capillaries In many cases these properties are interrelated: liver protection is connected with free radical restraining properties, antioxidant and anti-asthma properties in many cases are connected with properties that affect the function of various enzymes.

Research concerning the antioxidant effects of flavonoids started as early as the mid 60-s. The most studied compounds besides flavonoids found in plant extracts are quercetin, glucosoids and rutin. Phenolic antioxidants can act as free radical restrainers and iron ion chelators. The iron ion chelator and complex forming indicators show the same properties, namely, that the specific flavonoid molecules due to their structure attach to the transition ligands, mainly in iron (II) ions in a way that they prevent the iron ions from forming chemical reactions. This means that iron (II) cannot turn into iron (III), namely it cannot start a lipid-oxidation process and thus cannot produce newer harmful free radicals. Other chemicals like citric acid, potassium citrates (E 331, E 332) additives have such characteristics and are used for this purpose. The measure of antioxidant effects of flavonoids are determined by structure of the molecules at hand and also by what kind of chemical reactions the go through once in the body (gastro-intestinal tract, bile, liver).

The protective qualities of flavonoids in the cardiovascular system are primarily but not exclusively due to their antioxidant effects. It is a well known fact that the oxidation of the low-density lipo-protein molecule group (LDL) in the bloodstream is responsible for atherosclerosis

According to research flavonoids are able to slow down the oxidation process of LDLs and prevent them from attaching themselves and doing damage to the walls of veins and arteries.

The antithrombotic and thrombcita aggregation preventive properties of flavonoids are known since the 50′s. This means certain types of flavonoids can prevent abnormal blood platelets from causing thrombosis. The flavonoids are able to influence processes that play a role in cancer development. The results indicate that flavonoids can inhibit the function of tumor forming enzymes. They also help in ridding the body of tumor forming compounds before they have their effects.

DIETARY INTAKE

According to surveys conducted in different countries on average we consume between 20 and 50 milligrams of flavonoids daily. Since flavonoids are found only in plants, vegetarians consume a lot more than this amount. An independent researcher in the 70′s reported that our daily intake of all polyphenol compounds reaches the 1000 milligram (1gram) amount.

According to our local research Hungarian children consume 19,5 mg-s of flavonoids daily while adults consume 18,8 mg-s daily. Our values showed a large variation between individuals (0-179,3 mg for children, 0,5-309,7 mg for adults). According to this there are individuals with an unbelievably low intake of flavonoids. In accordance with the information stated below this has been a very important factor concerning the large amount of illnesses connected to poor diet in our country.

In the Seven Country Study of 1960 scientists looked into the dietary patterns of the population including flavonoid consumption and analyzed mortality data connected to cardio-vascular illnesses. The researchers recorded death cases over a 25 year period and found that there was a reversed connection to flavonoid consumption, cardiovascular disease and mortality. This correlation means that individuals where low-flavonoid intake is typical are more likely to get sick of cardiovascular disease than those who consume higher amounts of flavonoids. Flavonoid intake and its relationship to death were also analyzed in 1985 in the Netherlands. Based on the 5 most common dietary patterns the daily average intake of the population was 26mg / day. Most of the flavonoid intake was from tea (61%), the remaining 38% from fruits and vegetables (especially onions, cabbages, apples). In the 5 year follow up period data showed that people with a high amount of flavonoid intake had 50% less cardio-vascular related deaths than people with a low intake of flavonoids.

In other countries, small and large retail groups also carried out similar surveys and almost all ended with the conclusion that the development of cardio-vascular diseases can be curbed with a balanced diet in which flavonoid rich fruit and vegetables play a great role. The same goes for our country. A large portion of the population has a low intake of flavonoids and lives unhealthy lifestyles and thus is susceptible to damage from free radicals. We now know that the role of flavonoids and other polyphenols compounds in the human body are mainly of preventive nature. They either inhibit the development of diseases or slow down their process thus keeping us healthy. Only the medicines that have been tested and registered have therapeutic effects. According to current data excessive intake of flavonoids cannot harm us. No diseases have been connected to high flavonoid (vegetarian) diets. However there is no scientific data concerning the prolonged intake of flavonoids in concentrated forms such as dietary supplements. Doctors’ advice and experienced side-effects along with the careful observance of active and inactive periods of dietary supplement intake can however ensure our safety.