Dr Mike MacDonald

What is Apolipoprotein B (Apo B)?

Apolipoprotein B

Table of Contents

Lipoproteins are particles that transport fats through the bloodstream. They consist of three main components: triglycerides, cholesterol, and apolipoprotein (apo). Fats are not water soluble so they need a protein to package them up so they can be transported in the blood. ApoB is one of those packaging proteins. 

ApoB is found in the heaviest of the lipoprotein particles: VLDL (very low-density lipoprotein), IDL (intermediate density lipoprotein), and LDL (low-density lipoprotein). ApoB plays a key role in lipid metabolism as it transports cholesterol from your liver to other parts of your body.

What is ApoB?

ApoB stands for “apolipoprotein B,” it is found on VLDL, IDL, and LDL particles. There is only one ApoB protein on each lipoprotein particle. Therefore your ApoB measure is equivalent to the number of LDL, IDL, and VLDL particles you have in your blood.

Any particle that contains an ApoB molecule can end up in the artery wall and cause atherosclerosis. LDL particles are the most abundant particle in most people so your ApoB measure is equivalent to your LDL particle number.

There is good evidence that ApoB is the most powerful measure of heart attack risk, more powerful than LDL-cholesterol.

How Is ApoB Measured and how much does it cost?

ApoB is measured in a simple blood test. It is not usually included in a standard lipid panel. You should ask your doctor to include it. It is a very cheap test, costing less than $25.

What Are Normal Levels of ApoB?

Normal levels of apoB depend on your age and sex. Check out my percentile calculator here to see where you fit. The units are g/l and mg/dl. for example, 0.8g/l = 80mg/dl. As a general rule, everyone should aim for an ApoB < 100mg/dl. If you really want to prevent heart disease then aim even lower ie < 60mg/dl. That is what I am shooting for.

What Are Abnormal Levels of ApoB?

The higher your ApoB level the higher your risk of heart and vascular disease. As a rule of thumb, anything over 120 mg/dl is higher than average.


ApoB is a protein that packages up cholesterol to form LDL, VLDL, and IDL particles. It is a cheap and simple test that allows you to estimate your atherogenic lipid particle count. If you have high levels of apoB, it indicates that you have a high risk of developing heart disease. Your goal is to get it lower to live free of heart disease!

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