Vitamins are organic compounds, which human's organism cannot produce (or produces them in little amount in digestive system thanks specific bacterial flora), they must be provided together with food in finished form or form of provitamins, which during metabolism acquire full biologic activity. Vitamins - complementary factors, this term was introduced by Polish biochemist Kazimierz Funk, who in 1911 had separated a compound of such character and called it vitamin B1.
Vitamins are compounds which are neither a source of energy nor structural tissue ingredients but they are essential to organism growth and correct run of metabolism processes. Their biological action is visible just at very small concentration.
Mechanism of vitamin action is different but all of them affect directly or indirectly cell metabolism processes, most frequently as so called co-enzymes or biologically active ingredients of hormone character.
As it is well-known, deficiency of any vitamin in organism causes hypovitaminosis and their deficiency avitaminosis. Even little deficiency of vitamins may lead to different kinds of disorder and increase hazard of occurrence of so-called civilization diseases. Excessive consumption or overdose of some of them is also very harmful and may be a reason of disease caused by their excess - hypervitaminosis, with symptoms of poisoning.
Classification of vitamins, functions, food sources, nutritional requirements, interesting facts
Fat soluble vitamins. They can be stored so organism in higher grade may tolerate their periodical deficiency.
Water soluble vitamins. These vitamins are stored in organism in little grade so a nutritious dose should contain their optimum amount.