A Low Density Lipoprotein (LDL) is a substance made up of fat (lipid) and protein. Its function is to carry cholesterol and fats (triglycerides) in the blood. LDL carries cholesterol from the liver, through the blood, to the tissues of the body where it is stored. It is called ‘bad cholesterol’ because high levels are bad. (Source: www.nps.org.au/)