What is Apolipoprotein B? What role does it play in the body?

Apolipoprotein B, often abbreviated as ApoB, is the main protein found in low-density lipoproteins (LDL). LDL cholesterol is known as "bad" cholesterol because high levels of it can damage your heart and arteries. The ApoB test can help your healthcare provider figure out your risk for cardiovascular disease.

Like other lipoproteins (think, the “L” in HDL and LDL cholesterol), ApoB is responsible for transporting cholesterol throughout the body. It’s critical that cholesterol gets transported because cholesterol is needed to produce the hormones that are important for cellular health and function.


Cholesterol can only enter the arterial wall within ApoB particles, and the quantity of cholesterol that will be deposited is determined by the rate at which ApoB particles are trapped within the arterial wall, as opposed to those that pass harmlessly through.


The biomarker ApoB provides a direct measure of the number of these particles in the bloodstream and can more accurately predict the potential risks associated with these particles.