Vitamin A in health promotion and disease prevention

Vitamin A (retinol) is a fat-soluble vitamin that is readily destroyed upon exposure to heat, light, or air. The vitamin has a direct role in vision and is a component of a pigment present in the retina of the eye. It is essential for the proper functioning of most body organs and also affects the functioning of the immune system. Vitamin A is required for healthy skin and mucus membranes, and for night vision.

Vitamin A deficiency results in various disorders that most commonly involve the eye and the epithelial tissues the skin and the mucous membranes lining the internal body surfaces. An early symptom of vitamin A deficiency is the development of night blindness, and continued deficiency eventually results in loss of sight. If deficiency is prolonged, the skin may become dry and rough. Vitamin A deficiency may also result in defective bone and teeth formation. Its absence from diet leads to a loss in weight and failure of growth in young animals and to a general susceptibility to infections and diseases. It is thought to help prevent the development of cancer.

Excessive intake of vitamin A causes a toxic condition. The symptoms may include nausea, coarsening and loss of hair, drying and scaling of the skin, bone pain, fatigue, and drowsiness. There may also be other health violations: blurred vision and headache in adults, growth failure, enlargement of the liver, and nervous irritability in children.

Vitamin A is structurally related to carotene. Carotene is converted into vitamin A in the liver, two molecules of vitamin A are formed from on molecule of beta carotene, hence good sources of carotene, such as green vegetables are good potential sources of vitamin A. Vitamin A is manufactured by extraction from fish-liver oil and by synthesis from beta-ionone.

Good sources of Vitamin A - Butter, margarine, milk, cheese yogurt, cream, sweet potatoes, butternut squash, carrots, red peppers, chilies, leeks lettuce, broccoli, Swiss chard, spinach, tomatoes, watercress, basil, coriander, parsley, apricots, cantaloupe melons, mangoes, papayas, guavas, Sharon fruit. HERE and HERE you can find large selection of high quality and low priced supplemental vitamins.