Heart & circulation
apoB: the cholesterol number that actually matters
A standard cholesterol test weighs the cargo. apoB counts the delivery trucks, and the number of trucks tells you more about what ends up in your artery walls than the cargo does.
Your GP checks total cholesterol, and maybe LDL cholesterol. Both measure one thing: how much cholesterol is floating in your blood. But cholesterol doesn't drift into your artery walls on its own. It's carried there inside particles, and it turns out the number of particles matters far more than the amount of cholesterol they're carrying.
Cholesterol is the cargo. apoB counts the trucks.
Every particle that can lodge in an artery wall (LDL, VLDL, IDL, Lp(a)) carries exactly one protein called apolipoprotein B, or apoB. One particle, one apoB. So when a lab measures apoB, it's effectively counting your artery-clogging particles directly.
Lower apoB
fewer particles
Higher apoB
more particles · same cholesterol
Both carry the same cholesterol. The artery on the right has more particles, so more lodge in the wall and build plaque. That particle count is what apoB measures.
Why it beats a standard cholesterol test
Two people can have the same LDL cholesterol but very different particle counts. This is common if you carry extra weight around the middle, have raised triglycerides, or are insulin-resistant: you make lots of small, dense LDL particles. Each one carries less cholesterol, so your LDL number can look reassuring while the particle count quietly runs high. apoB catches what LDL misses.
What apoB tells you that cholesterol doesn't
As a rough guide, under about 0.9 g/L is a reasonable place to be, and lower again if you are already at higher cardiovascular risk. There is no single universal target: European guidance sets apoB goals by risk category, from under 1.0 g/L at moderate risk to under 0.65 g/L at very high risk (ESC/EAS 2019). Your doctor sets the right target for you. This is a guide, not a diagnosis.
The good news
The things that lower LDL usually lower apoB too: less saturated fat, more fibre and unsaturated fats, regular movement, not smoking, and, where a doctor advises it, medication. You don't need a separate plan, just the right number to track.
Should you test it?
apoB adds most where a standard cholesterol panel is likely to under-read your risk: a family history of early heart disease, raised triglycerides, type 2 diabetes, or extra weight around the middle. European guidance singles out exactly those groups as the ones where apoB is worth measuring.
- You've been told your cholesterol is 'borderline' and want to know what it really means
- You have a family history of heart attack or stroke before 60
- You have raised triglycerides, high blood sugar, or a larger waist
- You want to track one number as diet, exercise or medication takes effect
apoB analysis is recommended for risk assessment, particularly in people with high triglycerides, diabetes mellitus, obesity or metabolic syndrome, or very low LDL-C.
2019 ESC/EAS Guidelines for the management of dyslipidaemias
One number is never the whole picture
apoB is one input, not a verdict. Cardiovascular risk is judged on the whole picture: your age, blood pressure, smoking, family history, diabetes and weight, as well as your lipids. In the UK that is usually pulled together with a tool like QRISK3, which does not use apoB at all. A high apoB does not mean you will have a heart attack, and a low one does not mean you cannot. It is a good marker to know and to track. It is not a diagnosis, and interpreting it is a job for your doctor.
apoB will be included in our cardiovascular and longevity panels when we open.
Join the waiting list