Why is HDL cholesterol protective?
It appears that it’s not the cholesterol itself that is good, it’s the “vehicle.” There is some evidence that the HDL molecule “scours” the walls of blood vessels, cleaning out excess cholesterol. If this is the case, the cholesterol that HDL carries is actually “bad” cholesterol that’s just been removed from blood vessels, and is being transported back to the liver for further processing. Both LDL and HDL carry chemically identical molecules of cholesterol; it is the fate of the cholesterol that differs between these two types of molecules. LDL, which is the largest component of serum cholesterol, stays in the bloodstream where it can slowly build up in the inner walls of the arteries that feed the heart and brain. HDL carries its cholesterol away from the arteries and back to the liver where it’s passed from the body.
