What is cholesterol?

Cholesterol is a waxy substance found naturally in the blood. Cholesterol is produced in the liver, but is also present in foods such as meat, high fat cheese, butter and eggs. Cholesterol is essential for many of our body’s functions. For example, cholesterol is an important constituent of the walls of cells and is used to produce important hormones. Because cholesterol is not soluble in blood, it is transported in blood in particles called lipoproteins. The two most well-known of these particles are LDL and HDL. When you have your blood cholesterol levels measured, these are typically reported separately. LDL-cholesterol is the amount of cholesterol in LDL particles, HDL-cholesterol is the amount of cholesterol in HDL particles.

When people speak about “bad” cholesterol, they refer to LDL-cholesterol. The higher the blood levels of LDL-cholesterol, the higher the risk of myocardial infarction, stroke, and other diseases of the heart and blood vessels. When people speak of “good” cholesterol, they refer to HDL-cholesterol. It helps to remove excess cholesterol and returns it to the liver where it is broken down. Cholesterol-lowering therapies, such as statins, reduce blood levels of LDL-cholesterol.