These molecules are very hydrophobic and in the intestine become coated with an outer shell of apoproteins, phospholipids and nonesterified cholesterol. These other molecules become oriented such that their hydrophobic tails are facing the central core and their hydrophilic portions face the aqueous environment of the plasma. The lipoproteins leave the intestines in the form of chylomicrons. The apoproteins are lipids with specific proteins attached to them. There are 4 different lipoproteins found in the blood that are clinically important.
Chylomicrons are the largest and least dense.
They are transported across the intestinal mucosa to the blood. The enzyme lipoprotein lipase found on capillary endothelial cells in adipose tissue, skeletal muscle and the heart liberates free fatty acids which are taken up and remetabolized to triglycerides for storage. The remaining chylomicron remnant is taken up by the liver and metabolized to free fatty acids, glycerol, free cholesterol and proteins. Therefore, the major fate of dietary fat is transfer of the triglycerides to the adipocytes and cholesterol to the liver. In the postabsorptive state, VLDL, produced by the liver from free fatty acids, is the major source of plasma triglycerides.