Vitamin A, also called retinol, is a fat-soluble antioxidant with multiple functions that include promotion of vision and bone growth and health. Itís found naturally in a wide variety of red, yellow, dark green leafy, and orange vegetables and some fruits. Milk and eggs ae also good sources of vitamin A.
When vitamin A was first discovered in 1913, its primary function appeared to be the promotion of healthy vision, particularly in light-gathering cones. Later, many non-vision related functions were discovered, including vitamin Aís involvement in the proper function of the immune system, the reproductive system, and embryonic development. A lack of vitamin A in the motherís diet causes impaired growth, low immune system function, and birth defects in a newborn.
Vitamin A is used in many prescription acne creams, like Retin-A; this directly affects epithelial cells, decreasing the number of mucus-secreting cells and maximizing keratin-producing cells, which causes the skin to peel. It also makes the skin more susceptible to ultraviolet damage. Itís also used medically to treat certain types of leukemia because it boosts the healthy white blood cells.
Vitamin A comes in two forms: retinoids, from animal products, which are active vitamin A, and carotenoids, from plant products, which are actually vitamin A precursors. Vitamin E taken in conjunction with vitamin A prevents the intestines from chemically changing vitamin A into something else. Too much vitamin A is dangerous and even deadly; it will also tint human skin orange.
Web Resources On Vitamin A
Vitamin A and Carotenoids
Vitamin A (Retinol)
Book Resources On Vitamin A
The Doctor's Complete Guide to Vitamins and Minerals by Mary Dan Eades
Prevention's Healing with Vitamins: The Most Effective Vitamin And Mineral Treatments For Everyday Health Problems And Serious Disease by Alice Feinstein (Ed.)