Apolipoprotein B is a protein found in the blood that plays a key role in the metabolism of cholesterol and other lipids. High levels of Apolipoprotein B have been linked to an increased risk of heart disease and stroke. The Apolipoprotein B blood test is a simple and reliable way to measure the levels of this protein in your blood. With this test, you can better understand your risk of cardiovascular disease and take steps to improve your overall health. This test is recommended for individuals with a family history of high cholesterol or heart disease, as well as those who are overweight or have high blood pressure.