Vitamin A was initially known as a "fat-soluble" Vitamin that was first recognized in the year of 1913. Vitamin A is also called as retinol (also retinal or retinoic acid), a term much favored by manufacturers of various cosmetic products for skin care in order that aims to delay the ageing process (anti-aging products).
Vitamin A also has some chemical names like retinol palmitate and retinol acetate. Vitamin A is basically a collective name that includes compounds having the biological activities of retinol that was basically isolated from the retina of the eye! Vitamin A is absorbed in the body when it is in the form of retinol. Plant pigments known as carotenoids get converted into retinol by the body with the process of metabolism. Such pigments are found in many fresh vegetables and fruits and these are labeled as ‘provitamins A’ as they are precursors of the Vitamin A. Nevertheless, not all of the carotenoid forms got significant provitamin A activities.
The most active form of the provitamins is known as a beta-carotene. This element is time honored subject of many clinical trials since recent years as it is said to have strong anti-cancer action. Retinol is a fat-soluble vitamin that is derived from a couple of sources. Simply put, retinoids and provitamin carotenoids are found in animal sources such as liver, kidneys, eggs, and dairy products. Carotenoids such as beta-carotene (possessing profound vitamin A activities) are found in plants (vegetables and carrots) those are of dark or yellow color.
Recommended daily allowance (RDA) level for vitamin A (oral dose) have been established by the United State Institute for Medicine of the National Academy of Sciences (USIMNAS) to keep deficiencies of retinol a bay. Generally, vitamin A is said to be non-toxic, however, excess dosing can end up in acute or chronic toxicity.
