Vitamin A comes in two forms, retinol, found only in foods of animal origin, and carotene, which is found in foods of both plant and animal origin. Vitamin A is fat-soluble.

Vitamin A requires fat as well as minerals to be properly absorbed. A lack of zinc, vitamin C, vitamin E or protein can inhibit the proper absorption and function of vitamin A in the body. Protein cannot be utilized by the body without Vitamin A.Vitamin A stimulates white blood cell function and increases antibody response. Vitamin A may enhance the immune system because it is an antioxidant, protecting against colds, flu and infections of the kidneys, bladder, lungs and mucous membranes. As an antioxidant it helps to protect the cells against cancer and other diseases and is necessary for new cell growth.

Vitamin A may help to prevent night blindness and other eye problems. Vitamin A protects against heart disease and stroke; lowers cholesterol levels and slows the aging process.Vitamin A is also required during the growth of cell membranes and also for repair of cell membranes during wound healing.

Other functions of vitamin A include glycogen synthesis, protein metabolism, hormone synthesis, and as a coenzyme in the skin, bone, retina, liver and adrenal glands.

Deficiency signs
Vitamin A depletion may play a significant role in Chron's disease and gastric ulcers. Dry skin and hair, dryness of the conjunctiva and cornea may indicate Vitamin A deficiency. When the body is deficient in vitamin A, mucus-producing cells (soft) are replaced by keratin-producing cells (hard). The secretion of mucus diminishes and the mucous membranes which become toug h and relatively inflexible, leaving the body defenseless against invading organisms. Other indications of deficiency may include insomnia, fatigue, sinusitis, abscesses in the ears, pneumonia, weight loss, skin disorders such as acne, and reproductive difficulties.

Factors which rob us of vitamin A
Antibiotics, sulfur drug s, contraceptive drug s, alcohol, cortisone, oestrogen, mineral oil, coffee, some types of indoor lighting, air pollution, laxatives and some cholesterol-lowering drug s either prevent absorption or interfere with the absorption of vitamin A.

Good food sources
Butter, whole milk, liver, fortified low fat and skim milk, dark green leafy vegetables and yellow and orange vegetables. Foods that contain significant amounts include apricots, asparagus, beeroot greens, broccoli, cantaloupe, carrots, collards, dandelion greens, dulse, fish liver and fish liver oil, garlic, kale, mustard greens, papayas, peaches, pumpkin, red peppers, mustard greens, papayas, peaches, pumpkin, red peppers, spinach, spirulina, sweet potatoes, Swiss chard, turnip greens, watercress and yellow squash. Animal sources of vitamin A are up to six times stronger than vegetable sources.

Precautions Excess consumption of Vitamin A in either supplement form or in cod liver oil may result in toxicity. Should be avoided in the fat based form in pregnancy.