Apolipoprotein B, or ApoB, is a protein that plays a crucial role in lipid metabolism. It is a primary component of several types of lipoproteins, including low-density lipoprotein (LDL) and very low-density lipoprotein (VLDL). ApoB helps transport fats and cholesterol through the bloodstream, making it essential for maintaining healthy levels of these substances in the body. High levels of ApoB are associated with an increased risk of cardiovascular diseases, as it can lead to the buildup of plaque in arteries. Monitoring ApoB levels can provide valuable insights into an individual's heart health and help guide treatment strategies for conditions like atherosclerosis.