Final answer:
The precursor to vitamin A in plants is ß-carotene, a powerful antioxidant transformed into vitamin A in the liver. It aids in vision, immune function, and supports healthy skin, bones, and teeth. Too much vitamin A, however, can cause hypervitaminosis due to its fat-soluble nature.
Step-by-step explanation:
The vitamin A precursor in plants is ß-carotene, which is an effective antioxidant in the body. In humans, the transformation of ß-carotene into vitamin A primarily occurs in the liver using an enzyme called ß-carotene 15, 15'-oxygenase. ß-Carotene is cleaved at its central double bond by this enzyme in a reaction dependent on vitamin E, releasing two molecules of vitamin A aldehyde (retinal). Retinal is then reduced to vitamin A alcohol (retinol), which is essential for various body functions including vision, immune health, and cellular communication.
Vitamin A is fat-soluble and absorbed through the intestinal tract with lipids in chylomicrons. Excessive accumulation of fat-soluble vitamins can lead to hypervitaminosis, which is an excess of vitamins that are stored in the body's lipid stores.