Low-density lipoprotein
Low-density lipoprotein is one of the five major groups of lipoproteins, which, in order of molecular size, largest to smallest, are chylomicrons, very low-density lipoprotein, intermediate-density lipoprotein,
LDL, and high-density lipoprotein. Lipoprotein molecules enable the transportation of lipids, such as cholesterol, phospholipids, and triglycerides, within the water around cells, including the bloodstream. Studies have shown that higher levels of type-B LDL particles are associated with health problems, including cardiovascular disease. Recently both the lipid composition and protein composition of this lipoprotein were characterised in great detail. Although the nickname is overly simplistic and thus misleading, LDL molecules are often informally called
bad cholesterol because they can transport their content of many fat molecules into artery walls, attract macrophages, and thus drive atherosclerosis. In contrast, HDL molecules are frequently referred to as
good cholesterol or
healthy cholesterol, because they can remove fat molecules from macrophages in the wall of arteries.