Cholesterol is a waxy substance created and used by the body; it is essential to your health. Some of the cholesterol you need is produced by your body, while some comes from the food you eat. Your cholesterol levels are a major factor in your risk of heart attack or stroke. There are different types of cholesterol including LDL and HDL. Each type has different functions and effects on your body.
Lipoproteins
LDL and HDL stand for low- and high-density lipoprotein. Cholesterol and other lipids do not mix well with the blood and as such, lipoproteins must transport them throughout the blood. Lipoproteins are comprised of a lipid core, which is covered by special proteins. These proteins are designed so that one portion mixes well with lipids, while the other, mixes well with water-based liquids such as the blood.
LDL and HDL Structure
LDL and HDL molecules are different on a structural level. HDL is the smallest lipoprotein and 95 percent of its lipids are cholesterol. The remaining 5 percent are made up of another type of lipid known as triglycerides. LDL molecules are somewhat larger than HDL and are made of 90 percent cholesterol and 10 percent triglycerides. HDL and LDL also differ in the proteins that are present on their surfaces; HDL molecules have the protein Apolipoprotein A-I, whereas LDL molecules contain Apolipoprotein B. These proteins are important for the function of LDL and HDL molecules.
Function
Cholesterol is synthesized in the liver and also comes from the diet. Cholesterol must be transported to other tissues, which is one of the main roles of the LDL protein, as it facilitates movement of cholesterol from the liver to the rest of the body. HDL molecules, on the other hand, work as scavengers of cholesterol. They pick up excess cholesterol from the body and take it back to the liver for excretion.
Importance
The reason why LDL and HDL molecules are important is due to their roles in cardiovascular disease. If you have high levels of LDL cholesterol, you have an increased risk of heart attack or a stroke because these molecules can deposit cholesterol in the walls of your arteries, resulting in narrowing of the arteries and/or blockages. Because HDL molecules can scavenge excess cholesterol, they can protect you from cardiovascular problems.
