Vitamins: Properties and Features
Vitamins are the substances which take part in biological processes of the human body. People, animals, birds and fishes need vitamins. Plants need vitamins, too.
Functions of Vitamins
Vitamins fulfil the following functions in the human body:
- They act as accelerants;
- They serve as hormones;
- They act as exogenous prohormones.
Vitamins do not serve as a «building material» for tissues and neither do they serve as a source of energy although presence of these substances is not required to form cells and promote metabolic processes.
Definition and Classification of Vitamins
Vitamins are denoted by letters of Latin alphabet and digital indices (like B1 B6, B12 etc.). Apart from that, they also have names, which are standard ones and approved by International Union of Pure and Applied Chemistry.
Acknowledged classification divides vitamins in two groups:
- Fat-soluble or lipovitamins such as A, D, E, K;
- Water-soluble such as vitamins C and B.
This classification also covers natural vitamins. Artificially synthesized substances are identical to natural ones in terms of their composition, but may differ in properties. For instance, Vicasol, which is synthesized analogue of vitamin K, can be diluted in water.
Vitamins in Human Body
Human body gets natural vitamins with foods and drinks; their synthesized analogues and extracted substances usually enrich BAAs and vitamin complexes.
There are also exceptions such as:
- Vitamin A, which is synthesized from carotene and other provitamins;
- Vitamins B3 and K, which are synthesized by bacteria in large bowel;
- Vitamin D, which appears in skin upon UV exposure.
Human body accumulated water-soluble vitamins in small amounts, excessive amounts of vitamins are removed from the body during water exchange. Fat-soluble substances are deposited in fatty tissues and liver.
Human body need small amounts of vitamins on a daily basis, yet body does not properly function if vitamin deficiency takes a place. Excessive consumption of vitamins is harmful for health. There is a range of problematic issues which arise when consumption of vitamins does change, such as:
- Vitamin deficiency (absence of vitamins in human body);
- Hypovitaminosis (deficiency);
- Hypervitaminosis (abundance).
Considering vitamin properties, hypervitaminosis is typical for fat-soluble vitamins, which tend to deposit in human body while hypovitaminosis and vitamin deficiency are typical for water-soluble substances.
Vitamins are destroyed under exposure to external factors. Stability of these substances is lowered by the following things:
- UV rays;
- pH of environment;
- High temperature;
Vitamins lose their properties when contacting sorbents, enzymes, iron ions, copper ions and other microorganisms. Sensitivity to external factors differs for different vitamins.
Some substances are non-vitamins and do not related to vitamins in any sense.
Provitamins are biochemical are the ancestors of vitamins. They are so-called raw material which is used to ensure synthesis of vitamins in the human body. The following provitamins are widely available:
- Ergosterol which is a polycyclic steroid precursor of the D2 vitamin that can be found in fungi and algae;
- Tryptophan – an amino acid, which is produced from vitamin B3;
- Carotene which is unsaturated hydrocarbon that forms vitamin A;
- 7-Dehydrocholesterol – substance in the skin tissue which forms vitamin D3.
Vitamin-like substances are mistakenly thought to be vitamins as they have similar impact upon human body. But actually they are not vitamins as they form in different way.
There are water- and fat-soluble vitamin-like substances.
Water-soluble vitamin-like substances are as follows:
- Choline (B4);
- Inositol (B8);
- Para-amino benzoic acid (B10);
- Orotic acid (B13);
- Pangamic acid (B15);
- Lipoic acid (N);
- S-Methyl methionine (U);
- L-Carnitine (carnitine).
Fat-soluble vitamin-like substances are the following:
- Fatty essential acids (vitamin F),
- Coenzyme Q (vitamin Q).
It is noteworthy that some vitamins and provitamins such as vitamin F etc. are not the one substance only, but a whole group of the substances which are similar in terms of properties and origin.
Vitamins: Discovery and Research
Vitamin C was first found and researched in the beginning of XX century. Then researchers discovered other vitamins. Nowadays, 13 substances are approved to be vitamins. Some compounds are still under consideration.