More about Vitamin A
Good sources of Vitamin A
Vitamin A is a family of fat-soluble vitamins. Retinol is one of the most active, or usable, forms of vitamin A, and is found in animal foods such as liver and eggs and in some fortified food products. Retinol is named after the vitamin that improves eyesight.
Retinol is often called preformed vitamin A. It can be converted to retinal and retinoic acid, other active forms of the vitamin A family.
Some plant foods contain darkly colored pigments called provitamin A carotenoids that can be converted to vitamin A.
Beta-carotene is a provitamin A carotenoid that is more efficiently converted to retinol than other carotenoids
Vitamin A plays an important role in vision, bone growth, reproduction, cell division and cell differentiation, which is the process by which a cell decides what it is going to develop into.
It helps maintain the surface linings of the eyes and the respiratory, urinary, and intestinal tracts. When those linings break down, bacteria can enter the body and cause infection. Vitamin A also helps maintain the integrity of skin and mucous membranes that function as a barrier to bacteria and viruses.
Vitamin A helps regulate the immune system. The immune system helps prevent or fight off infections by making white blood cells that destroy harmful bacteria and viruses. Vitamin A may help lymphocytes, a type of white blood cell that fights infections, function more effectively.
Some carotenoids, in addition to serving as a source of vitamin A, have been shown to function as antioxidants in laboratory tests. However, this role has not been consistently demonstrated in humans (1). Antioxidants protect cells from free radicals, which are potentially damaging by-products of oxygen metabolism that may contribute to the development of some chronic diseases
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