Vitamins
Vitamins, Just like hormones or enzymes, they perform regulatory functions in the system. Most vitamins work in the form of coenzymes. Because they cannot be created in the system, It is necessary to deliver them with food. It is also known, that some vitamins can be synthesized by the microflora of the human gastrointestinal tract (vitamin K2, vitamin B6), and vitamin D is not supplied solely with food, But under the influence of ultraviolet rays, it should be formed in the skin with 7-dehydrocholesterol.
Significant differences in the construction of vitamins hinder their chemical classification. That is why we use the division (for practical reasons) for fat -soluble and water -soluble. The first group includes vitamin A, D, E, K, and for the second vitamin C and vitamins of group B.
Is worth knowing, that the concept of individual vitamins is usually not one, But a few, A dozen or more chemical compounds (including synthetic substances currently produced by the pharmaceutical industry) with a similar physiological effect.