Vitamin A

Vitamin A

Vitamin A is key for good Vision, a healthy immune system, and cell growth. There are two types of vitamin A. This entry is primarily about the active form of vitamin A -- retinoids -- that comes from animal products. Beta-carotene (Provitamin)is among the second type of vitamin A, which comes from plants.

Sources

• Animal sources are liver oil, butter, milk , cheese & egg yolk.
• Plant sources in the form of Provitamin are tomatoes, carrots, yellow & green vegetables , spinach, fruits such as mangoes , papaya & sweet potatoes.

Daily requirement

• Adult : 3000-5000IU
• During pregnancy & lactation : 6000-8000IU
• Children : 2000-3000IU
• Infants: 1500IU

           1IU = 0.3microgm of Retinol

                  =0.6microgrm of beta-carotene

Absorption, storage & Transport

The liver is the major storage site ofvitamin A. For storage, the retinol will be transported from the hepatocytes to the stellate cells and converted back to retinyl esters, the storage form of vitamin A. If vitamin A is needed to be released into circulation, retinol will combine with