"The system is set up so that the HDL high density lipoproteins, or artery-cleaning or 'good' cholesterol, cleans out the LDL low density lipoproteins, or 'bad' cholesterol, " she explains.

CNN: Understanding the cholesterol numbers game

"Bad" cholesterol - low density lipoproteins (LDL) - contribute to furring of the arteries.

BBC: Drug raises 'good' cholesterol