Physicochemical basis of the digestion and absorption of triacylglycerol

Dietary lipids and many lipophilic vitamins and drugs are transported in lymph by chylomicrons which are secreted by the small intestine. This chapter reviews our current understanding of the digestion, uptake, intracellular metabolism, and packaging of dietary lipids into chylomicrons. A number of digestive enzymes are involved in the digestion of triacylglycerol, phospholipids and cholesterol in the lumen. Unilamellar vesicles (liposomes) in the lumen and lipid transporters in the mucosal brush border membrane are both important carriers involved in the uptake of digested fatty acids, monoglycerol, and cholesterol. This chapter also provides detailed information regarding the roles which intracellular fatty acid transporters, cholesterol transporters, and sterol carrier proteins play in lipid metabolism in the small intestine. In addition, the present review illustrates the mechanism by which intracellular assembly and modification occur during the formation of chylomicrons and very low density lipoprotein. Furthermore, clinical disorders related to intestinal lipid transport are discussed. The authors' basic and clinical insights into the processes of intestinal lipid absorption provide valuable information about effective, safe ways to prevent obesity and hyperlipidemia.