Apolipoprotein B (ApoB) is the primary protein component of low-density lipoprotein (LDL). The amount of cholesterol contained within LDL varies, but each LDL contains exactly one ApoB protein. Therefore, ApoB is a more reliable indicator of circulating LDL compared to LDL cholesterol. ApoB is strongly associated with increased risk of developing cardiovascular disease (CVD) and often outperforms LDL-C at predicting risk of coronary heart disease.