Vitamin

Vitamins are organic compounds that an organism needs not as energy carriers but for other vital functions, but which the metabolism cannot synthesize to meet its needs. Vitamins must be ingested with food, they belong to the essential substances. Plants normally do not need additional vitamins, they can synthesize all organic substances necessary for them themselves.

Some vitamins are supplied to the body as precursors, so-called provitamins, which the body then converts into the active form. Vitamins are divided into fat-soluble (lipophilic) and water-soluble (hydrophilic) vitamins. Chemically, 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 formed by plants, bacteria or animals. The vitamins are distinguished by naming them with different letters.

Different animals consider different substances to be vitamins. For example, most animals can produce vitamin C themselves instead of having to take it in with food. Dry-nosed primates, which include humans, some families in the order of bats and passerine birds, all 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 _A1), but they occupy a special position because, unlike almost all other animals, they cannot convert β-carotene into retinol.

In humans, the above definition applies to 13 organic compounds. Of these, 11 cannot be synthesized in any way by the organism itself. Cholecalciferol (also known as colecalciferol or calciol for short; vitamin D3 or imprecisely vitamin D) can be produced by the body itself, provided there is sufficient exposure to sunlight (photosynthesis). Self-synthesis also exists for niacin, which can be produced from the amino acid tryptophan. The necessary niacin intake depends on the amount of protein consumed and is thus influenced by dietary habits.

Task and function

Vitamins (in the vitamin balance) are involved in many reactions of the metabolism. Their task is to regulate the utilization of carbohydrates, proteins (colloquially also called protein) and minerals, they provide for their degradation or conversion and thus also serve the energy production. Vitamins influence the immune system and are indispensable for building cells, blood cells, bones and teeth. The vitamins differ in terms of their effects.

History

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 physician and chemist Nikolai Lunin fed mice an artificial mixture of the separated then known components of milk, namely proteins, fats, carbohydrates and salts. They died and Lunin concluded "that natural food such as milk must therefore contain small quantities of vital substances in addition to the hitherto known constituents".

After reading an article by the Dutch physician Christiaan Eijkman, the Polish biochemist Casimir Funk became intensively involved in 1911 with the isolation of the active ingredient against the vitamin deficiency disease Beri-Beri, a hitherto unexplained new disease that appeared in Japan and on Java. Eijkman had observed in a military hospital in Batavia that, in addition to patients and staff, chickens in the hospital's courtyard were showing symptoms of beri-beri (meaning sheep's walk) disease. The chickens were fed the same white husked rice that the patients and staff were fed. Beri-beri was accompanied by paralysis and loss of strength. This disease appeared only after European rice husking machines were introduced in these countries. It was thought to be a deficiency disease. The Japanese doctor Takaki Kanehiro was able to cure the disease by adding the removed rice bran back to the rice. Casimir Funk isolated a substance from rice bran which he hoped would have a curative effect against the deficiency disease. This substance, which Funk mistakenly called the beriberi vitamin in 1912, derived from vita (life) and amines, was neither an amine nor did it act against beriberi. In his search for the anti-beriberi factor, vitamin _B1 or thiamine, he had isolated nicotinic acid, vitamin B3. The latter is useless against beriberi, but showed effect in the treatment of pellagra.

The name also proved to be incorrect for other vitamins in terms of the literal sense, since many vitamins do not have amino groups. In 1926, vitamin _B1 (thiamine) was first discovered after nine years of work by the Dutch chemists Barend C. P. Jansen and Willem F. Donath in crystalline form from rice bran. In 1932 Windaus determined the elemental composition. In 1936, the structure of vitamin _B1 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 humans today were presented pure for the first time. In the meantime, chemical synthesis routes have also been developed for these vitamins.

Diseases resulting from vitamin deficiencies were not recognized as such until the beginning of the 20th century. On the assumption that they were nutrition-related diseases, attempts were initially made to combat certain diseases such as beri-beri, scurvy and rickets by supplying appropriate foods. After animal experiments confirmed the hypothesis that the diseases were caused by the lack of certain food components, further animal experiments led to the isolation of these special essential food components and from these finally the respective vitamins themselves.

In 1913, the designation of vitamins with large letters of the alphabet was introduced by the American biochemist Elmer McCollum. Thus, there was a vitamin A, B, C and D. Subsequently, vitamins E and K were added. When food containing vitamin B was analyzed, it turned out that this was more than one factor that could eliminate several symptoms. Thus, biologists spoke of vitamin _B1, _B2, and so on.

During the period of National Socialism (1933-1945), those in power in Germany very actively promoted the supply of the population with vitamins that had only just been discovered at that time. They wanted to "strengthen the body of the people from within" because they were convinced that Germany had lost the First World War partly as a result of malnutrition. In "vitamin campaigns", children, mothers, heavy workers and soldiers were supplied with vitamins, especially vitamin C, of which the Wehrmacht still had 200 tons produced in 1944.