Chylomicrons transport triacylglycerol, phospholipid, and cholesterol derived from dietary lipid from the small intestine to other tissues of the body. Each chylomicron assembles around a single molecule of apolipoprotein B-48 (Phillips et al. 1997) which at the time the particle leaves the intestine and enters the lymphatic circulation is complexed with >200,000 molecules of triacylglycerol (TG), ~35,000 of phospholipid, ~11,000 of cholesterol ester, ~8,000 of free cholesterol, ~60 copies of apolipoprotein A-I, ~15 copies of apolipoprotein A-IV, and copies of apolipoprotein A-II (Bhattacharya and Redgrave 1981; Havel and Kane 2001). As chylomicrons circulate in the body, they acquire molecules of apolipoproteins C and E, and through interaction with endothelial lipases can lose a large fraction of their triacylglycerol. These changes convert them to chylomicron remnants which bind to LDL receptors, primarily on the surfaces of liver cells, clearing them from the circulation. This whole sequence of events is rapid: the normal lifespan of a chylomicron is 30 - 60 minutes (Havel and Kane 2001).