There are two sources of dietary vitamin A.
Active forms, which are immediately available to the body are obtained from animal products.These are known as retinoids and include retinaldehyde and retinol.
Precursors, also known as provitamins, which must be converted to active forms by the body, are obtained from fruits and vegetables containing yellow, orange and dark green pigments, known as carotenoids, the most well-known being b-carotene.
In the intestine, vitamin A is protected from being chemically changed by vitamin E. Vitamin A is fat-soluble and can be stored in the body.
Most of the vitamin A consumed is stored in the liver.When required by a particular part of the body, the liver releases some vitamin A.