Vitamins are organic compounds that an organism does not need as a source of energy but for other vital functions, but which the metabolism cannot synthesize as required. Vitamins have to be taken in with food , they are essential substances . Plants usually do not need additional vitamins, they can synthesize all the organic substances they need on their own.
Some vitamins are supplied to the body as preliminary stages, so-called provitamins , which the body only then converts into the active form. Vitamins are divided into fat-soluble (lipophilic) and water-soluble (hydrophilic) vitamins. Chemically, the vitamins do not form a uniform group of substances. Since vitamins are quite complex organic molecules, they do not occur in inanimate nature. Vitamins must first be produced by plants, bacteria or animals. The vitamins are distinguished by naming them with different letters.
Different substances are sometimes considered to be vitamins in different animals. For example, most animals can produce vitamin C themselves instead of having to ingest it with their food. Drought-nosed primates , which also include humans, some families in the order of bats and passerines , all real bony fish and guinea pigs cannot do this because they lack the enzyme L- gulonolactone oxidase . Thus, for most animals, vitamin C is not a vitamin, but a metabolite . Cats also need retinol (or vitamin A 1 ), but have a special position because, unlike almost all other animals , they cannot convert β-carotene into retinol.
In humans, the definition given above applies to 13 organic compounds. Of these, 11 cannot in any way be synthesized by the organism itself. Cholecalciferol (also colecalciferol or calciol for short; vitamin D 3 or, inaccurately, vitamin D) can be produced by the body itself, provided there is sufficient exposure to the sun ( photosynthesis ). Niacin, which can be made from the amino acid tryptophan, also has its own synthesis. The necessary niacin intake depends on the amount of protein consumed and is thus influenced by eating habits.
Task and function
Vitamins (in the vitamin balance ) are involved in many metabolic reactions. Their job is to regulate the utilization of carbohydrates , proteins (colloquially also known as protein) and minerals , they ensure their breakdown or conversion and thus also serve to generate energy . Vitamins influence the immune system and are essential for building cells , blood cells , bones and teeth. The vitamins differ in terms of their effects.
|Year of discovery||vitamin||Isolation off|
|1913||Vitamin A ( retinol )||Fish liver oil|
|1918||Vitamin D ( Ergo- / Cholecalciferol )||Fish liver oil|
|1920||Vitamin B 2 ( riboflavin )||Eggs|
|1922||Vitamin E ( tocopherol )||Wheat germ oil|
|1926||Vitamin B 12 ( cobalamin )||liver|
|1926||Vitamin B 1 ( thiamine )||Rice bran|
|1929||Vitamin K ( phylloquinone )||alfalfa|
|1931||Vitamin B 5 ( pantothenic acid )||liver|
|1931||Vitamin B 7 ( biotin )||liver|
|1931||Vitamin C ( ascorbic acid )||lemon|
|1934||Vitamin B 6 ( pyridoxine )||Rice bran|
|1936||Vitamin B 3 ( niacin )||liver|
|1941||Vitamin B 9 ( folic acid )||liver|
That some diseases can be cured by certain foods was already known in the 16th century, when this fact was recognized for scurvy . In 1881, the Russian doctor and chemist Nikolai Lunin fed mice with an artificial mixture of the separated components of milk known at the time, namely proteins, fats, carbohydrates and salts. They died and Lunin concluded "that natural food like milk must therefore contain small amounts of vital substances in addition to the previously known components".
After reading an article by the Dutch doctor Christiaan Eijkman , the Polish biochemist Casimir Funk worked intensively in 1911 on isolating the active ingredient against the vitamin deficiency disease Beri-Beri , a hitherto inexplicable new disease that appeared in Japan and Java. In a military hospital in Batavia , Eijkman had observed that in addition to patients and staff, the chickens in the hospital courtyard were also showing symptoms of the Beri-Beri disease (in German: sheep walk). The chickens were fed the same white, husked rice that the patients and staff were given. Beri-Beri went hand in hand with paralysis and loss of strength. This disease did not appear until after European rice husking machines were introduced in these countries. A deficiency disease was suspected. The Japanese doctor Takaki Kanehiro was able to cure the disease by adding the removed rice bran to the rice. Casimir Funk isolated a substance from rice bran that he hoped would have a healing effect on the deficiency disease. This substance, which Funk erroneously called beriberi vitamin in 1912, derived from vita ( life ) and amine , was neither an amine nor was it effective against beriberi. While searching for the anti-beriberi factor, vitamin B 1 or thiamine , he isolated nicotinic acid , vitamin B 3 . The latter is useless against beriberi, but has shown effects in treating pellagra .
The designation also turned out to be literally wrong for other vitamins, since many vitamins do not have any amino groups. In 1926, after nine years of work, the Dutch chemists Barend CP Jansen and Willem F. Donath isolated vitamin B 1 (thiamine) in crystalline form from rice bran. In 1932, Windaus determined the elementary composition. In 1936, the structure of vitamin B 1 was elucidated at about the same time by Adolf Windaus , Richard Kuhn , Robert R. Williams and Rudolf Grewe . The synthesis was carried out in 1936 by Robert R. Williams and in 1937 by Hans Andersag and Kurt Westphal (1936).
Between 1920 and 1980 the 13 vitamins known to man today were presented in pure form for the first time. Chemical synthesis routes have also been developed for these vitamins.
Diseases as a result of vitamin deficiency symptoms were only recognized as such at the beginning of the 20th century. Assuming that these were diet-related illnesses, attempts were made to combat certain illnesses such as beri-beri, scurvy and rickets by taking appropriate foods. After animal experiments confirmed the hypothesis that the diseases were caused by the lack of certain nutritional components, further animal experiments led to isolating these special essential nutritional components and finally the respective vitamins themselves.
In 1913 the American biochemist Elmer McCollum introduced the designation of vitamins with capital letters of the alphabet . So there was a vitamin A, B, C and D. Then the vitamins E and K were added. When analyzing the food that contained vitamin B, it turned out that there was more than one factor that could eliminate several symptoms. Thus, the biologists spoke of vitamins B 1 , B 2 , etc.
During the time of National Socialism (1933–1945), the rulers in Germany very actively promoted the supply of the population with the vitamins that had just been discovered at the time. They wanted to "strengthen the national body from within" because they were convinced that Germany had lost the First World War as a result of malnutrition . In “vitamin campaigns”, children, mothers, hard workers and soldiers were supplied with vitamins, especially vitamin C , of which the Wehrmacht was still producing 200 tons in 1944.
Naming of vitamins
The Polish biochemist Casimir Funk assumed that all vital substances contained an NH 2 group. In 1912 he coined the term “vitamin” (from the Latin vita for life and amine for nitrogen-containing or organic nitrogen-containing compound) for such a supplementary nutrient . Later studies showed, however, that by far not all vitamins are amines and do not always contain nitrogen atoms. Examples are vitamin A (see retinol ) and vitamin C ( ascorbic acid ), a carboxylic acid. Other names for vitamins that have largely disappeared today were: completines , nutramines and accessory nutrients or supplements , because the chemically pure fats , proteins and carbohydrates are only supplemented to form full nutrients when vitamins (and minerals ) are added.
The chemical name of a vitamin is based on its chemical structure. The common names use letters, sometimes combined with a number. Gaps in the row of letters were created, among other things, because some of the original isolations turned out to be non-uniform substances and were removed from the row of vitamins. Sometimes there were or are several common names, but usually only one common name has prevailed.
Of the 20 vitamins currently known in medical science, 13 are considered essential for humans:
|* The letter designation for the vitamins niacin (B 3 ) and pantothenic acid (B 5 ) is used differently in the relevant literature.|
The "B vitamins" eight are under the collective name of vitamin B complex or simple as vitamin B summarized.
Other trivial names used in literature and other countries for (mostly incorrectly referred to as such) vitamins:
|Vitamin B 4||former name for adenine and choline|
|Vitamin B 5||outdated term for pantothenic acid and also vitamin B 3|
|Vitamin B 7||outdated term for biotin|
|Vitamin B 8||Unusual name for adenosine phosphate|
|Vitamin B 9||uncommon term for folic acid|
|Vitamin B 10||is also known as vitamin R or as para-aminobenzoic acid and is a mix of vitamins of the B group|
|Vitamin B 11||uncommon term for folic acid|
|Vitamin B 13||uncommon term for orotic acid|
|Vitamin B 14||is a mix of vitamins B 10 and B 11|
|Vitamin B 15||Unusual term for pangamic acid|
|Vitamin B 16||vitamin B 6 pyridoxine assigned|
|Vitamin B 17||Marketing for Laetrile ( Amygdalin )|
|Vitamin B 22||is said to be a component of aloe vera extract|
|Vitamin B H||hasty classification as a vitamin of para-aminobenzoic acid|
|Vitamin B T||hasty classification of L - carnitine as a vitamin (not essential for humans)|
|Vitamin B X||Unusual term for para-aminobenzoic acid|
|Vitamin F.||all essential fatty acids , especially linoleic acid and linolenic acid|
|Vitamin H.||Trivial name for biotin (also vitamin B 7 )|
|Vitamin I / J||allegedly proven substances with properties of the vitamin C ascorbic acid|
|Vitamin P.||Marketing for mixtures of different flavonoids , "permeability vitamin"|
|Vitamin PP||Trivial name for nicotin (acid) amide, see also vitamin B 3 (from: Anti-Pellagra)|
|Vitamin Q||Marketing for the non-essential ubiquinone|
|Vitamin R.||see vitamin B 10|
|Vitamin S.||see vitamin B 11|
|Vitamin T.||see vitamin B T|
|Vitamin U||misleading name for methyl methionine|
Certain vitamins can be stored in the body, you can eat them in reserve, so to speak, while others cannot be stored, but have to be continuously supplied through food . Then the vitamins are divided into two groups: the group of fat-soluble, storable vitamins and the group of water-soluble, non-storable vitamins.
Fat-soluble vitamins are non-polar molecules that are very soluble in lipids . Their resorption therefore requires the formation of micelles . They are built into chylomicrons in the cells of the intestinal mucosa in a manner similar to that of cholesterol .
The fat-soluble vitamins are:
- Vitamin A (retinol)
- Vitamin D (cholecalciferol)
- Vitamin E (tocopherol)
- Vitamin K ( K 1 , K 2 , K 3 , K 4 " coagulation vitamins " )
Despite its fat solubility, vitamin K can only be stored to a small extent by the body .
Because of its tasks in the body, vitamin D is no longer counted among the vitamins by some official bodies, but among the hormones. However, this classification is at least imprecise, because only the calcitriol , which is produced on the basis of vitamin D 3 via intermediate stages in the kidney, can be called a hormone in the full sense .
Water soluble vitamins
The water-soluble vitamins are precursors of coenzymes or prosthetic groups of various enzymes.
The water-soluble vitamins are:
- Vitamin C (ascorbic acid)
- Vitamin B 1 (thiamine)
- Vitamin B 2 (riboflavin)
- Vitamin B 3 (nicotinic acid, niacin)
- Vitamin B 5 (pantothenic acid)
- Vitamin B 6 (pyridoxine)
- Vitamin B 7 (biotin, vitamin H)
- Vitamin B 9 (folic acid)
- Vitamin B 12 (cobalamin)
Vitamin B 12 is an exception in that it can be stored by the organism despite its solubility in water.
Water-soluble vitamins are absorbed in the small intestine by means of carriers or receptors . While vitamin B 2 is absorbed through passive transport, vitamin B 1 , vitamin B 12 and vitamin C are actively absorbed .
Vitamin requirements and occurrence
Only a few examples are given here under “Effects” and “Occurrence”. More details can be found in the articles on the individual vitamins.
|Surname||Abbr.||Daily requirement of an adult according to the DGE||Effects||Occurrence||Deficiency symptoms (example)|
|Retinol||A.||0.8-1 mg||Affecting eyesight, affecting cell growth, skin renewal||Liver, milk fats, fish, as a provitamin in many plants||rarely, see hypovitaminosis of retinol|
|Cholecalciferol||D.||20 µg||Promote calcium absorption||Is produced by the body under the influence of UV; Fish products; in smaller quantities in milk||rickets|
|Tocopherols||E.||10-15 mg||serve for cell renewal, inhibit inflammatory processes, strengthen the immune system, act as radical scavengers||vegetable oils, in smaller amounts in leafy vegetables and whole grain products||rarely, see hypovitaminosis of vitamin E.|
|Phylloquinone||K 1||0.001-2.0 mg||Required for the formation of blood coagulation factors 2, 7 , 9 and 10 and their counterparts protein S and C . It is also required in bones for the synthesis of osteocalcin .||Eggs , liver, kale||Clotting disorders|
|Water soluble vitamins|
|Thiamine||B 1||1.3-1.8 mg||Influencing the carbohydrate metabolism, important for the thyroid function, important for the nerves||Meat, peas, oatmeal||beriberi|
|Riboflavin||B 2||1.8-2.0 mg||against migraines, promotes memory and concentration||Meat, green leafy vegetables , whole grain products||Skin problems|
|Niacin also nicotinic acid amide, nicotinic acid||B 3||15-20 mg||Utilization of fats, protein and carbohydrates, good for skin and nails||lean meat, fish, yeast||Pellagra|
|Pantothenic acid||B 5||8-10 mg||promotes wound healing, improves the defense reaction||Liver, wheat germ, vegetables||anemia|
|Pyridoxine||B 6||1.6-2.1 mg||protects against nerve damage, helps with protein metabolism||Liver, kiwi fruit, potatoes||hypochromic anemia|
|Biotin||B 7||0.25 mg||protects against skin inflammation, good for skin , hair and nails||Liver, cauliflower, by intestinal bacteria||seldom, especially due to a loss of absorption capacity, see deficiency symptoms of biotin|
|Folic acid also pteroylglutamic acid||B 9||0.16-0.40 mg||good for the skin||Liver, wheat germ, pumpkin||pernicious anemia , malformations in the unborn|
|Cobalamin||B 12||3 µg||forms and regenerates red blood cells , stimulates appetite, important for nerve function||Liver, fish , milk||pernicious anemia|
|Ascorbic acid||C.||100 mg||Protection against infections, acts as a radical catcher, strengthens the connective tissue||Rose hips , acerola cherries , citrus fruits , sea buckthorn , kiwis , peppers , cabbage , liver , potatoes , sauerkraut||scurvy|
Biological values are never absolute, but are always determined by a large number of factors. The vitamin requirement does not only depend on gender and age. It can be increased with physical and psychological stress, for example with occupational or environmental stress, illness, smoking and alcohol consumption, in women also during pregnancy and while breastfeeding. The information on vitamin requirements is therefore average values with a generalizing character.
The recommendations also vary accordingly. The German Nutrition Society (DGE), for example, recommends consuming 100 mg of vitamin C per day , while the World Health Organization (WHO) recommends only 30 mg per day. The daily requirement for most vitamins is in the range of a few milligrams (mg).
Of the 13 vitamins that are considered essential (indispensable) in medical science, two are not strictly essential, namely vitamin D (calciferol) and niacin (vitamin B 3 ). Substances with vitamin D and niacin properties can namely be formed ( synthesized ) by the body itself under certain circumstances . Vitamin D 3 ( cholecalciferol ) can arise from 7-dehydrocholesterol, a biological derivative of cholesterol , for example under the action of sunlight . Niacin can be formed when tryptophan is broken down.
Some bacteria in the intestinal flora are able to synthesize vitamins K and B 12 . If they are destroyed by taking strong antibiotics , a deficiency can easily arise. However, there are medical options to reintroduce these bacteria in the intestine.
The vitamin content of fruits depends on numerous factors such as the nature of the soil, storage time, etc. The preparation temperature and duration can also play a role.
Deficiency symptoms and oversupply
In Germany, deficiency symptoms are only possible in exceptional cases. Only with the vitamin folic acid has a possible undersupply been discussed more often. People who adhere to the dietary requirements of the German Nutrition Society (DGE) and their diet on fruits, convert enough vegetables, whole grains, some meat and dairy products are adequately supplied with all the essential vitamins and, accordingly, have a suffizienten or adequate vitamin status on if the corresponding biomarkers are within the established limit values.
In the case of a vitamin deficit, the vitamin intake is insufficient to cover the requirement. A vitamin deficiency can arise as a result of an increased requirement (during pregnancy and breastfeeding, in childhood and adolescence), due to insufficient intake, through malassimilation as a result of other underlying diseases, as a result of taking medication (oral contraceptives) or after parenteral nutrition without the addition of vitamins. The vitamin content also varies through the storage and preparation of the food, so that a deficiency can arise despite the selection of the right food.
This can lead to deficiency symptoms, which are gradually divided into hypovitaminosis or avitaminosis. Vitamin deficiency diseases have become rare under European nutritional conditions and are mostly due to alcohol addiction . Old people, smokers or vegetarians can also be affected. The symptoms vary depending on the vitamin affected. Depending on the type and extent of the damage, the organism can recover. If there is a lack of vitamin B 1 , beri-beri occurs . A lack of vitamin C leads to scurvy . Vitamin A deficiency leads to night blindness and dry skin. Vitamin K deficiency increases the tendency to bleed as it is required for the synthesis of some coagulation factors .
In alcoholics , several factors lead to a vitamin deficiency. The chronically addict consumes hardly any food other than the addictive substance; he suffers from malnutrition. The lining of the digestive tract over the esophagus, stomach and small intestine can be severely damaged, as can the pancreas. Ingestion of food is associated with nausea, vomiting, and diarrhea. The digestion and absorption in the gastrointestinal tract is disturbed ( malabsorption , maldigestion ). Damage to the blood count and nerve tissue occurs v. a. due to a deficiency in vitamins B 1 ( Wernicke-Korsakow syndrome ), vitamin B 6 and folic acid ( polyneuropathy ) and B 12 ( pernicious anemia , funicular myelosis ). The defense against infection is reduced. The blood clotting is - disturbed - for various reasons.
An oversupply of vitamins is called hypervitaminosis. The fat-soluble vitamins (E, D, K, A) can be stored in the body, mostly in the liver. This can also lead to overdosing. The water-soluble vitamins are quickly excreted through the kidneys.
Hypervitaminoses are those symptoms that can occur with excessive intake of the corresponding vitamins. This cannot be achieved through conventional nutrition. However, high-dose vitamin doses are possible.
Vitamin D in connection with calcium is undisputed in the treatment of osteoporosis. With chronic ingestion of concentrations above 0.3 mg / d, the permanent accumulation in the body can have the opposite effect; bone decalcification and thus the development of osteoporosis are promoted. The provitamin beta-carotene (precursor of vitamin A) can presumably increase the risk of lung cancer in smokers in high doses. For the vitamins of the B group (water-soluble), undesirable effects at high doses are only known for vitamin B 6 ; if more than 50 mg per day - twenty times the daily dose - is taken, sensory polyneuropathy results . The Federal Institute for Risk Assessment regularly prepares maximum quantity proposals for the use of vitamins (and minerals) in food and dietary supplements.
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