Many think that hypercholesterolemia and hyperlipidemia are synonymous. But they are not. Hypercholesterolemia may be considered as a type of hyperlipidemia. This article will discuss hypercholesterolemia and hyperlipidemia and the differences between them in detail.
Food we eat contains carbohydrates, lipids, proteins, and minerals. Gastro intestinal system breaks down these compounds down to its constituent molecules. Carbohydrates get broken down to simple sugars. Proteins get broken down to amino acids. Lipids get broken down to fatty acids and glycerol. Body can also synthesize new body lipids from fatty acids and glycerol. Body contains three types of fats. They are structural fats, neutral fats and brown fats. Structural fats are an inherent component of membranes. Neutral fats get stored in fat tissue. Brown fat, commonly found in infants, helps maintain body heat.
Lipid metabolism is a complex ongoing process. It runs in both ways. Lipids get broken down to fatty acids and glycerol during digestion while, in another place, fatty acids and glycerol join to form complex lipids. There are two kinds of fatty acids in our food. They are saturated and unsaturated fatty acids. Saturated fatty acids have hydrogen atoms occupying all available binding sites on carbon; therefore do not have double or triple bonds. Unsaturated fatty acids have double or triple bonds. If there is one such bond, the fatty -acid gets sub-categorized as monounsaturated fatty acids. If there are many such bonds, it is called a polyunsaturated fatty acid. From a healthy eating point of view, saturated fatty acids are unhealthy.
There are specific enzymes in the gastro intestinal tract capable of breaking complex fats down (ex: pancreatic lipase). When we eat oily food, these enzymes break the fat down to fatty acids and glycerol. These compounds get absorbed into the gut lining cells and then into the blood stream flowing from gut to the liver. Fatty acids are found in blood as free fatty acids as well as bound to albumin. Gut lining cells and liver cells form large complex lipoproteins called chylomicrons. Liver also forms very low density lipoproteins. The density of the lipoprotein is inversely proportionate to its lipid content. Very low density lipoproteins and chylomicrons contain very small amounts of cholesterol and a large amount of lipids. These enter the blood streams and goes into tissues. Some lipids inside chylomicrons and VLDL gets absorbed into cells by the action of lipoprotein lipase, and the density of the lipoproteins rise forming Intermediate density lipoproteins (IDL). IDL gives off lipoproteins to High density lipoproteins (HDL) due to the action of lecithin-cholesterol acyl-transferase, forming LDL. Peripheral tissues and liver form cholesterol due to the action of HMG COA reductase. Cholesterol goes from peripheral tissues to the liver in HDL. HDL contains mostly cholesterol and fewer lipids. HDL is also known as good cholesterol, and LDL is known as bad cholesterol in layman’s terms. HDL is protective against atheromatous plaque formation. Macrophages engulf LDL and become foam cells. These get deposited in the vessel walls during atherosclerosis.
What is the difference between Hypercholesterolemia and Hyperlipidemia?
• Hypercholesterolemia is above normal levels of cholesterol in the blood.
• Hyperlipidemia is above normal lipid levels in the blood.
• Hyperlipidemia includes lipoproteins, lipids, cholesterol and cholesterol esters.
• Hypercholesterolemia is less harmful than other hyperlipidemias.