Lipoproteins are complex molecular structures composed of lipids and proteins that are essential for the transport of fats and fat-soluble substances in the blood and other body fluids. Since lipids such as cholesterol, triglycerides and phospholipids are largely insoluble in water, they cannot circulate freely in the aqueous environment of blood plasma. Lipoproteins solve this problem by packaging lipids with specific proteins called apolipoproteins, thereby allowing them to be transported between the intestine, liver and peripheral tissues. In biological anthropology and Research Methods in Anthropology-II, the study of lipoproteins is important because their concentration and distribution can provide information about nutrition, metabolism, health status, disease susceptibility and biological variation among human populations. Structurally, a lipoprotein consists of a hydrophobic core surrounded by a hydrophilic outer layer. The core mainly contains triglycerides and cholesteryl esters, while the outer surface contains phospholipids, free cholesterol and apolipoproteins. Apolipoproteins have several functions. They provide structural stability to lipoprotein particles, help in the recognition of lipoproteins by specific receptors, and regulate enzymes involved in lipid metabolism. Different classes of lipoproteins contain different combinations of apolipoproteins and consequently perform different physiological functions. Lipoproteins are commonly classified according to their density, which depends largely on the relative proportions of lipid and protein. The major classes are chylomicrons, very-low-density lipoproteins (VLDL), intermediate-density lipoproteins (IDL), low-density lipoproteins (LDL) and high-density lipoproteins (HDL). Chylomicrons have the lowest density because they contain a very high proportion of lipid and relatively little protein. HDL has the highest density because it contains a comparatively greater proportion of protein. Chylomicrons are formed mainly in the intestinal cells after the absorption of dietary fats. They transport dietary triglycerides and cholesterol from the intestine to muscles and adipose tissue. Their triglycerides are progressively removed by the action of lipoprotein lipase, an enzyme