The purpose of this review is to update the reader on our current understanding of the uptake and secretion of dietary
lipid by the enterocyte to the periphery. This is a multi-stage process that first involves
luminal digestion, followed by cellular uptake and processing, and subsequent extracellular transport of
chylomicrons. We discuss the importance of
acid and pancreatic
lipase in
lipid digestion. Micellar solubilization of
fatty acids and 2-mono-acyl
glycerol is critical to uptake by enhancing enterocyte exposure. There is controversy regarding the mechanism of
fatty acid uptake by the enterocyte and whether this is mediated by a carrier-dependent process. The mechanism of
fatty acid transport to the endoplasmic reticulum is discussed including the role of
fatty acid binding proteins. Intracellularly, 2-monoacylglycerol and
fatty acid are reconstituted to form
triacylglycerol by the action of MGAT and DGAT. We focus on the mechanisms of intracellular
chylomicron formation and secretion into lymph.
Chylomicron and VLDL particles differ not only by an operational definition but likely represent two distinct pathways of intestinal
lipoprotein formation. The physiologic role of
apo B-48 in the intestine is presented as well as clinical disease of
chylomicron metabolism, specifically
abetalipoproteinemia and Anderson's disease.