Apolipoprotein B

What it is

Apolipoprotein B (ApoB) is the main protein on LDL and other artery-clogging ("atherogenic") particles. Each such particle carries exactly one ApoB, so the value counts how many of them you have.

Why it matters

ApoB is often a better gauge of heart-disease risk than LDL cholesterol alone, because it counts particles rather than the cholesterol inside them.

What high values can mean

A higher value means more atherogenic particles circulating, which is associated with greater risk of plaque build-up and cardiovascular disease.

What low values can mean

A lower value means fewer atherogenic particles, generally considered protective for the heart.

How to improve it

Diet changes (less saturated and trans fat), exercise, weight management and, when a clinician advises, lipid-lowering medication can lower ApoB.

Food & lifestyle

Favour vegetables, fibre, fish and unsaturated fats; limit fried foods, fatty processed meats and refined carbohydrates.

Preparing for the testFasting required

Drawn with a lipid panel; fasting may be requested but is often not required for ApoB — follow your lab's instructions.

When to talk to a doctor

Discuss raised ApoB with a doctor, particularly alongside a family history of early heart disease.

Related markers

• Apolipoprotein A1
• LDL Cholesterol
• Non-HDL Cholesterol

Sources

• MedlinePlus (NIH)
• Testing.com (AACC)

Content reviewed on June 26, 2026