Apolipoprotein B (ApoB) is an important component of very-low-density lipoprotein (VLDL), the intermediate-density lipoprotein (IDL), and the low-density lipoprotein (LDL) that are involved in atherosclerosis and cardiovascular disease. ApoB plays a central role in carrying cholesterol and triglycerides from the liver and gut to utilization and storage sites. ApoB levels may be increased during pregnancy or coffee consumption, as well as during the fall and winter seasons. The apoB100 test measures the amount of this type of cholesterol in the blood. LDL is often referred to as “bad” cholesterol because high levels of it can damage the heart and blood vessels.