Define the Absorption of Vitamin A?
Vitamin A and carotenoid tend to aggregate with lipids into globules, which then pass into the small intestine. Dietary vitamin A (retinol) is absorbed as such in the intestines. Retinyl esters (mainly palmitate) arc hydrolyzed by the combined action bile salts and the esterases in the small intestine. The released carotenoids and retino1 in the small intestine are solubilised into micelles i.e., small aggregates of mixed lipids and bile salts suspended within the gastric bolus (material taken into the body by way of. The digestive tract)solution. The micelles are absorbed into the intestinal mucosal cell. Approximately 70 to 90% of retinol from the diet is absorbed as long as the diet is adequate in fat. Carotenoid absorption from the diet ranges from about 20% to 50%, but carotenoid absorption may be as low as 5%.