VITAMIN A AND HIS FUNCTIONS IN THE HUMAN LIFE

Vitamin A is one of the vitamins that are needed by the human body. This vitamin is listed first because it is a type of vitamin that was first discovered by scientists. Widely vitamin A is a generic name that states all retinoids and precursor / provitamin A / carotenoids have biological activity as retinol. (Suhardjo, 2002).

Most compounds contained in Vitamin A is retinol compounds. These compounds dominate the content of Vitamin A, which is essentially the general content of Vitamin A include retinol, retinyl palmitate, and retinyl acetate.

Vitamins that have the chemical formulaC₂₀H₃₀O this vitamin

abundant in carrots, tomatoes, yellow yam, mango, pumpkin, papaya, spinach, broccoli, watercress, egg yolks, fish oils, milk, cheese, and liver.

If deficiencies are then the body can suffer respiratory problems and even blindness myopia, whereas excess intake of vitamin A can cause nausea, headaches, joint pain, irritation, and hair loss.

FUNCTION OF VITAMIN A
The function and role of Vitamin A include:

1. In Sense of Sight
   Compounds in Vitamin A, which acts as the establishment and maintenance of the sense of sight is retinol compounds. This is because Vitamin A will help convert the signal molecules of light received by the retina to be a projection image in our brains. Together with rhodopsin, retinol compound will form a complex light-sensitive pigment to transmit light signals to the brain. Therefore, if someone has a deficiency of Vitamin A, he runs the risk of eye disease.
2. Balancing the immune system
   Vitamin A has an important role in maintaining the immune system of a person. This is because foods containing Vitamin A will quickly clean the toxins and bacteria that enter the human body.
   Scientifically, the performance of this vitamin is to increase the work activities of white blood cells and antibodies in the body so that the body becomes more resistant to the toxin compounds against invading microorganisms and parasites, such as pathogenic bacteria and viruses.
3. Keeping Healthy epithelium
   Epithelium is one of the four types of tissue in the human body. The main function of this network is as protective and secretion (release of the results glands or active cell). Epithelial tissue damage can cause a variety of diseases, such as cancer of the epithelial tissue of the skin.
4. Role in Reproductive Process
   The basic point here is that arising from the increased consumption of Vitamin A in pregnant women.

To prevent vitamin A deficiency, then held high-dose vitamin A regular twice in one year. High-dose vitamin A supplementation conducted periodically in children, intended to raise reserves of vitamin A in the liver, to prevent vitamin A deficiency and the resulting bad consequences such as blindness and death. Reserves of vitamin A in the liver can be used at any time when needed. (Puspitorini, 2008)