Omega-3 Fatty Acids and Lipoproteins

Abstract

There are five major classes of lipids in blood: free fatty acids, phospholipids, triglycerides, cholesterol esters and free cholesterol. Lipids are generally insoluble in aqueous solution and need to be bound to proteins to facilitate their transport. Free fatty acids are transported in the blood bound to albumen, the other lipids are carried by the plasma lipoproteins. The plasma lipoproteins are lipid — protein complexes of density d < 1.21g/ml. They are classified in terms of their hydrated density, as determined in the preparative ultracentrifuge. Four classes of lipoprotein particles are present in the plasma of normal fasting human subjects: very low density lipoprotein (VLDL) d < 1.006g/ml, intermediate density lipoprotein (IDL) d 1.006–1.019g/ml, low density lipoprotein (LDL) d 1.019–1.063 g/ml and high density lipoprotein (HDL) d > 1.063 g/ml. Particles of a fifth class, the chylomicrons (d < 1.006g/ml), appear in the plasma a few hours after a fatty meal and are gradually cleared from the circulation.