Vitamin A-Absorption, Transport & Uptake by the Tissues
Absorption of Vitamin A
- Intestine is the major site of absorption of Vitamin A.
- Beta carotene is first cleaved by a di-oxygenase and to Retinal is formed.
- In the next step, Retinal is reduced to Retinol.
- The absorption is along with other fats and requires bile salts.
- In biliary tract obstruction and steatorrhea, Vitamin A absorption is reduced.
- Within the mucosal cell, the retinol is re-esterified with fatty acids and then incorporated into chylomicrons. Then it is transported to liver.
- Vitamin A is stored as Retinol palmitate in the liver stellate cells.
Transport of Vitamin A from Liver to Tissues
- The Vitamin A from liver is transported to peripheral tissues as Trans-retinol by the Retinol Binding Protein (RBP).
- One molecule of RBP binds one molecule of retinol.
- In the case of Vitamin A deficiency…
FOR COMPLETE LESSON GO TO BIOCHEMISTRY I, CLICK VITAMINS TAB AND THEN CLICK SURRICULUM TO VIEW THE LIST OF LESSONS.