An overview and classification of vitamins

Vitamins are organic compounds essential to human metabolism. The human body is like a very complex chemical plants, constantly engaged in a variety of biochemical reactions. Its response is closely related with the enzyme catalysis. Enzyme to generate activity, participants must have a coenzyme. Many vitamins are known to the enzyme composition of coenzyme or coenzyme molecule. Therefore, the vitamin is to maintain and adjust the body's normal metabolism of the important material. That the best vitamin on a "bio-active substances" in the form found in human tissues.

Vitamin content of food less, the body's requirements are not many, but it is absolutely essential substances. Diet such as lack of vitamins, can cause human metabolic disorders, so as to cause vitamin deficiency. Such as the lack of vitamin A will appear night blindness, dry eye and dry skin; a lack of vitamin D may be suffering from rickets; a lack of vitamin B1 available beriberi; a lack of vitamin B2 may be suffering from cheilitis, angular cheilitis, glossitis and scrotal inflammation; the absence of PP can be suffering from niacin; a lack of vitamin B12 may be suffering from pernicious anemia; a lack of vitamin C may be suffering from scurvy.

Vitamin is a huge family, As far as known there are dozens of kinds of vitamins can be divided into two major categories of fat-soluble and water-soluble. (See below) some substance in the chemical structure similar to a vitamin, after a simple metabolic reactions can be transformed into vitamins, such substances called pro-vitamin, such as β-carotene can be transformed into vitamin A; 7 -- dehydrocholesterol can be transformed into vitamin D3; but after a number of complex metabolic reactions in order to become nicotinic acid tryptophan can not be called pro-vitamin. Water-soluble vitamins absorbed from the intestine, through the circulation to the body's need for organization, the excess part of the mostly urine, very little storage in the body. Most of fat-soluble vitamins by bile salts to help absorb into the body through the lymphatic system organs. The body can store a large number of fat-soluble vitamins. Vitamin A and D key are stored in the liver, vitamin E mainly stored in body fat tissue, vitamin K less storage. Water-soluble vitamins are not easily soluble in water, soluble in non-polar organic solvents, absorbed their stored little more from the urine of excessive discharge; fat-soluble vitamins dissolve in non-polar organic solvents, are not easily soluble in water, With the fat, the body can absorb and store up in the body, excretion rate is not high.