Vitamins are organic compounds required as essential nutrients by the body of a living organism. Human body needs vitamins from food because it is not capable of synthesizing them on its own. Vitamins obtained from diet are typically required in very small amounts, and different living species may have different needs for specific vitamins. It might be interesting to mention that vitamin C, which is one of the most important vitamins in humans, is not required for the most of the other animals.
Classification of vitamins
There are thirteen different vitamins, which are classified by biological and chemical activity. The basic classification of vitamins includes water-soluble or fat-soluble vitamins. There are four fat-soluble vitamins: vitamin A, D, E and K. Water-soluble vitamins include 8 vitamins from B family and vitamin C. The main difference between these two groups of vitamins is that water-soluble ones dissolve in water, and they are easily excreted from the body. This way, body needs to replenish them every day through a rich and proper diet. Fat-soluble vitamins are absorbed through the intestinal tract, with the help of fats. Deficiency of fat-soluble vitamins is very rare, since these vitamins tend to accumulate in the body. Consequently, fat-soluble vitamins can lead to hypervitaminosis.
Importance of vitamins
Every living multi-cellular organism needs vitamins for normal growth and development. Vitamins and minerals are necessary even in the prenatal phase, when the fetus starts to grow. In this stage, they are crucial for different chemical reactions in the body and development of skin, muscular tissue and bone structure. Vitamins are typically obtained from the food, but some of them are even produced inside of the human body. For example, various bacteria forming the gut flora, produces vitamin K and biotin. On the other hand, vitamin D is synthesized in the skin, and the body needs ultraviolet sunlight to make this vitamin on its own. Vitamin D deficiency, associated with many diseases, often occurs among people who do not get enough of the sunlight. Humans can also produce vitamin A from beta-carotene and niacin. All of these vitamins are essential to maintain health of the cells, tissues and organs, and to process various other complex nutrients such as proteins, carbs and lipids.
Functions of different vitamins
Vitamin A is necessary for good eyesight, and it helps in growth and maintaining the healthy skin. The B vitamins are important for metabolic activity; they are involved in production of red blood cells, and for healthy nervous system. Vitamin C keeps the tissues healthy, aids in healing the wounds, and fights against hazardous free radicals. Vitamin D is needed for healthy bones, as it helps in absorption of calcium. Vitamin E maintains many of the bodily tissues, protects the lungs and aids in formation of red blood cells. Vitamin K regulates the clotting of the blood.