About vitamins - in general
...Later, the term "vitamin" extended to other substances, which are subsequently detected in food, and it's typical to have
an important role in the human body. Most of them do not have the structure of amines.
Although these substances are vital for many processes of life, their biological significance is the first time observed the emergence of some serious diseases, which are observed since ancient times. The story of the vitamin, is one of the most important episode in the history of biochemistry and nutrition primarily relies on human health.
Vitamins participate in the growth process and are essential for health of every man. Some vitamins are important participants in the reactions in which they creates the energy necessary for the functioning of the organism. Vitamins can therefore be considered as an important source of biological energy.
Since vitamins are very different by its characteristics, chemical structure, the role of the body, etc they can be divided
based on their solubility. So there are fat soluble and water soluble vitamins. Their solubility in large part, indicates the quantity of each vitamin that is found in the body. Vitamins soluble in fats (such as vitamins A, D, E and K), in the gastro-intestinal tract behave in the same way as fat food. The absorption of these vitamins is associated with normal fat absorption. Hence, steatorrhea (disease in which there is a large amount of fat in the feces), and biliary system disorders can lead to poor absorption of fat-soluble vitamins. After absorption these vitamins transport and accumulate in the liver (vitamins A,
D and K) or in the
adipose tissue (E). If these vitamins accumulate and store in a large quantities, it can lead to serious consequences for the organism (especially for vitamin A and vitamin D), because these vitamins are not excreted in urine (or are secreted in insufficient quantities). But, there is a greater probability of occurrence of these vitamins in bile and then their excretion in feces. Unlike them, water-soluble vitamins, such as vitamin C and vitamins of the B group, does not accumulate in the body, but the excess of these vitamins is excreted in urine. Their structures were rather different. All water-soluble vitamins (exception is vitamin B12) can be synthesized by plants, and provide legumes, grains, green leafy vegetables, and yeast, meat and milk. Because of their solubility in water (vitamins of the B group and vitamin C) they don't have a stable form for disposal and have to be constantly taken in with food. They therefore can not be disposed in the body to toxic levels.
Needs for certain vitamins increases during the rapid growth of man, during pregnancy, lactation, severe physical and mental effort, at exhaustion, and some illnesses (hyperthyroidism).
Vitamins are organic compounds, chemically very different from one to another. They are hydrocarbon compounds (compounds that contain carbon and hydrogen atoms in their chemical structure, as well as some other elements). Since they are present in various foods, the proper nutrition will always have enough of the necessary vitamins. However, few people can always afford a food that is rich in these nutrients (many vitamins can easily decompose at elevated temperatures, and it would take a lot of variety of food), so they often resort to the enrichment of foods with various vitamins. Many people consume vitamins in the form of various products.
The absence of vitamins in foods leads to the appearance of hypovitaminosis, and the complete lack of vitamins in food - deficiency disease. If this continues for a long time vitamin deficiency can lead to serious health problems of the body, and even death.
In some particular cases (such as a treatment of various diseases with vitamins) can lead to excess of vitamins in the body. This phenomenon is called hypervitaminosis and, as well as deficiency can have very negative effects on the life and health of humans and animals.
The largest number of activated vitamins in the cells are involved in cellular metabolism, as a cofactor of the enzyme (enzyme-activating factors binding to them) and are called biological catalysts. Unlike them, the active form of vitamin D plays a ignificant role as a hormone in the regulation of calcium levels in the body and producing of leukocytes (white blood cells).
Some vitamins (such as vitamin K) does not always come from food. A certain amount of vitamin K is produced by bacteria in the intestine.
U nekim određenim slučajevima (kao što su neki tretmani
sa vitaminima pri lečenju raznih bolesti) može doći i do
prekomernog unošenja vitamina u organizam. Ta pojava se
naziva hipervitaminoza i ona, isto kao i
hipo- i avitaminoza može imati jako negativne efekte na
život i zdravlje čoveka i životinja.
Najveći broj aktiviranih vitamina u ćelijama učestvuje
u ćelijskom metabolizmu kao kofaktori enzima
(faktori koji aktiviraju enzime vezujući se za njih) i
nazivaju se biološki katalizatori. Za razliku od njih,
aktivna forma vitamina D igra ulogu
hormona značajanog za
regulaciju nivoa kalcijuma u organizmu
i stvaranje leukocita (belih krvnih zrnaca). Vitamin
takođe ne mora uvek poticati iz hrane. Šta više u hrani ga
ima u manjoj količini, nego što je organizmu potrebno, ali
zato određenu količinu vitamina K
stvaraju bakterije u intestinumu (tankom crevu).