Role of vitamin A for eye health is not a secret anymore. Vitamin A is a vitamin needed by the retina of the eye in the form of certain metabolites, molecules absorb light in the retina. This molecule is absolutely necessary for both scotopic and color vision. Vitamin A also acts in a very different role, as a form of retinoic irreversibly oxidized acid, which is a hormone-like growth factor essential for epithelial cells and others. It turned out that vitamin A is still saving many uses.
Sources Of Vitamin A
Like other vitamins, vitamin A can be obtained from anywhere. The easiest source is to be gained from dark green vegetables. This is because in it contains provitamin A (beta-carotene). The body will change the pro-vitamin A into vitamin A. One molecule of beta-carotene can be converted into two molecules of vitamin A. Beta-carotene is much found in spinach, carrots, sweet potatoes and orange-yellow fruits.
As for other source comes from from animals, are often called preformed vitamin A. Form of preformed vitamin A include liver, kidney, butter, fortified margarine (the addition of certain substances in foods such as vitamin A), egg yolks, milk, and cheese.
Vitamin A or beta-carotene include vitamins that are relatively heat resistant, unlike vitamin C or B. Therefore, even if cooked, its vitamin A content remains high.
Vitamin A Benefits
Vitamin A is closely associated with the eye, it certainly is much to know. Yes, vitamin A is important to help the integrity of the retina. Lack of vitamin A will cause the eye can not adjust to changes in light entering the retina. As the beginning consequence, there was a nyctalopia, the eye is difficult to see at twilight.
Another benefit of vitamin A is to help the growth and development of the skeleton and the body tissue. Because vitamin A helps the body's protein synthesis and differentiation of bone cells (bone repair process). Vitamin A also serves as an anti-infective vitamin, because it can maintain the integrity of mucous membranes (so that the cells in the body especially the eyes are not fragile).
Therefore, vitamin A deficiency can also cause increased susceptibility to infections of bacteria and viruses. In other words, without vitamin A, the body's defense system will be lost, so the body will be susceptible to disease.