Cholesterol is vital to human health, but an oversimplified view of cholesterol — that high-density lipoprotein (HDL) cholesterol is good, and low-density lipoprotein (LDL) cholesterol is bad — has led to a gross misunderstanding of the nuances that define the differences in cholesterol-containing lipoproteins. An assay that quantifies low-density lipoprotein particle size and concentration based on a principle of physics called ion mobility may be better at identifying those at risk for heart disease. This Aliquot segment features Dr. Ronald Krauss, a physician with expertise in internal medicine, endocrinology, and metabolism.