Vitamin A General Info
Article Highlights
- 2 dietary sources of vitamin A: preformed vitamin A (retinol) and carotenoids such as beta-carotene.
- Carotenoids are converted to vitamin A inside the body.
Vitamin A is one of the four fat soluble vitamins required for normal metabolism, growth and general health. The other fat soluble vitamins include vitamins D, E, and K. Vitamin A in not synthesized in the body and must be obtained through the diet. There are two dietary sources of vitamin A:
- Pre-formed vitamin A (retinol)
- Pro-vitamin A carotenoids
Pre-formed vitamin A (retinol) occurs in animal tissues only and not in vegetables. Inside the body, retinol can be converted to retinal and retinoic acid, which are other active forms of vitamin A. Pro-vitamin carotenoids such as beta-carotene are precursors to vitamin A and are converted to vitamin A inside the body as well.
Carotenoids are found in many yellow, orange and green, leafy fruits and vegetables. The average adult receives half his vitamin A as pre-formed vitamin A and the rest as carotenoids. Vitamin A is stored primarily in the liver.