Illustration of the provenance of cholesterol, where it is stored and its elimination. One third of cholesterol is provided by food and the remaining two thirds by the liver. It is transported through the bloodstream by two types of protein: -LDL which carries it to the tissue but which, when too great in quantity for the blood vessels, blocks them up forming an atheromatous plaque which can burst and form a thrombus (clot). This is known as bad cholesterol. -HDH, which carries the cholesterol to the liver where it will be recycled and eliminated. This is known as good cholesterol.