Cholesterol can’t dissolve in the blood. It has to be transported to and from the cells by carriers called lipoproteins. Low-density lipoprotein, orLDL, is known as “bad” cholesterol. High-density lipoprotein, orHDL, is known as “good” cholesterol. These two types of lipids, along with triglycerides and Lp(a) cholesterol, make up your total cholesterol count, which can be determined through a blood test.
LDL (Bad) Cholesterol
When too muchLDL (bad) cholesterol circulates in the blood, it can slowly build up in the inner walls of the arteries that feed the heart and brain. Together with other substances, it can form plaque, a thick, hard deposit that can narrow the arteries and make them less flexible. This condition is known as atherosclerosis. If a clot forms and blocks a narrowed artery, heart attack or stroke can result.
HDL (Good) Cholesterol
About one-fourth to one-third of blood cholesterol is carried by high-density lipoprotein (HDL).HDL cholesterol is known as “good” cholesterol, because high levels ofHDL seem to protect against heart attack. Low levels ofHDL (less than 40 mg/dL) also increase the risk of heart disease. Medical experts think thatHDL tends to carry cholesterol away from the arteries and back to the liver, where it’s passed from the body. Some experts believe thatHDL removes excess cholesterol from arterial plaque, slowing its buildup.