What is Cholesterol? Cholesterol is a fat-like substance in the body and is produced by the liver. It is carried by proteins called lipoproteins for transport through the blood. There are two main types of lipoproteins: LDL (bad cholesterol) and HDL (good cholesterol). LDL transports cholesterol into the tissues, while HDL transports cholesterol back to the liver. Cholesterol Plaques and Their Effects When cholesterol levels rise, they accumulate on the vessel walls, causing hardening and [...]