The liver then packages the cholesterol and triglycerides, along with special proteins, into tiny spheres called lipoproteins. The lipoproteins are released into the circulation, and are delivered to the cells of the body. LDL, HDL and VLDL are the names of the three major varieties of lipoproteins. Only a small proportion is from HDL cholesterol. Thus, the total cholesterol level in the blood is usually a reflection of the amount of LDL cholesterol.
Atherosclerotic plaques cause narrowing of the arteries, and lead to heart attacks and strokes.
Much evidence has now accumulated that increased HDL cholesterol levels are associated with a lower risk of heart disease, and that low HDL cholesterol levels are associated with an increased risk of heart disease. Thus, HDL cholesterol appears to be good. There is some evidence that the HDL molecule scours the walls of blood vessels, and cleans out excess cholesterol. Apparently, unlike some bad humans, bad cholesterol can be rehabilitated. Triglycerides get little respect.