Image courtesy of Shutterstock
There are two types of cholesterol in the blood: LDL-C, so-called 'bad' cholesterol, which is carried in low-density lipoproteins (LDL), and HDL-C, so-called 'good' cholesterol which is found in high-density lipoproteins (HDL).
Lowering LDL-C (e.g. by statins) has been demonstrated to reduce the risk of heart diseases and stroke, but the causal role of HDL-C is less clear even though observational studies have shown an inverse association between HDL-C and risk of cardiovascular diseases.