VITAMIN A' AND OUR HEALTH
Vitamin A is a fat soluble vitamin which occurs in two forms in nature. It occurs in its true form (also called retinol) in animal foods such as fish oil and liver. In this form , it is readily used by the body. It is stored in and released by the liver. However, in order to be transported throughout the body, it needs a special protein carrier. Hence the importance of adequate protein intake when vitamin A intake is increased.
Vitamin A also occurs in vegetables in the form of Beta carotene, or provitamin A, which is the precursor of the actual vitamin. Beta carotene is abundant in root vegetables such as carrots and yams, leafy vegetables such as spinach and kale, and yellow fruits such as cantaloupe and mango.
Beta carotene cannot be directly used by the body as a actual vitamin A. it has to be converted into retinol in the presence of fats and bile before this can happen. This is why it is advisable, when eating a salad, to sprinkle a little salad oil on it. In this respect cooked carrots are better than raw ones, as the cooking of the carotene helps the liver to convert it to the retinol form of vitamin A.
Beneficial effects:
Vitamin A helps to fight colds and infections, particularly in the mucous membranes of the eyes, ear, nose throat, lungs and bladder. It increases the resistance of these tissues to bacterial infections. As for the eyes, Vitamin A is necessary for the formation of the photosensitive pigment known as visual purple; this contains beta carotene, vitamin A and protein, and maintains good vision.