Why Measuring ApoB Is The Key To Preventing Heart Disease.
ApoB. The central risk factor that is rarely tested.
Preventing heart disease is possible.
You just need to know how.
To prevent heart disease, you need to know what causes it, how to measure the relevant factors and what to do about them.
When we say heart disease, what we really mean is plaque in the artery wall.
This Is Known As Atherosclerosis.
The fundamental cause of atherosclerosis is when a cholesterol particle crosses into the artery wall from the bloodstream, gets stuck, and sets off an inflammatory process1.
Think of a splinter of wood getting stuck underneath your skin and causing persistent inflammation.
Every cholesterol particle has a protein marker called ApoB on its outside.
We also refer to these cholesterol particles as ApoB particles.
For every cholesterol particle, there is one ApoB protein.
Therefore, the number of ApoB particles is a direct measure of the number of circulating cholesterol particles in your bloodstream.
These ApoB particles move cholesterol around your body.
Over your entire lifetime ApoB particles will be crossing into your artery wall. Most of these will come right back out, but some will be retained and cause atherosclerosis.
This is a cumulative process, which means that even though ApoB levels might remain constant in your bloodstream the atherosclerosis that results grows and grows.
Theoretically, if there were no ApoB particles, there would be no atherosclerosis.
No atherosclerosis. No heart attacks.
No atherosclerosis and the leading cause of death worldwide would be no more.
As the number of ApoB particles increases, the risk of atherosclerosis increases.
For every one standard deviation increase of ApoB, the risk of coronary artery disease increases by 65%2.
But My Doctor Has Never Mentioned ApoB?
Most doctors, including cardiologists, do not routinely measure ApoB.
Given its foundational relationship to the cause of the leading cause of death, this is not ideal.
But why do doctors not measure it?
The reason is that measuring LDL cholesterol on a standard lab panel is a reasonable approximation of ApoB in most people.
But I will stress the words ‘reasonable’ and ‘most’ in that last sentence.
Using LDL cholesterol to guide your decisions is ok but not great.
Usually LDL -C roughly equates to levels of ApoB.
Except in the setting of type 2 diabetes, metabolic syndrome, insulin resistance and obesity.
The rates of all of these conditions have been increasing rapidly, and with that increase comes a drop in the reliability of approximating ApoB from LDL-C.
This results in a phenomenon called discordance where LDL-C levels can appear normal, but ApoB levels can remain high, and so too does the risk of heart disease.
Except that you are unaware of this increased risk.
When this occurs, the future risk of dying from any cause increases by 21%, and the chances of a heart attack increase by 49%3.
When both LDL-C and ApoB are at low levels, that increased risk disappears.
Not knowing your ApoB can be costly.
What ApoB Should You Aim For?
That all depends on your overall risk of a future cardiovascular event like a heart attack.
If you already have evidence of substantial plaque on a cardiac CT or have had a heart attack already, your future risk is significantly increased.
While we have very clear guidance on what LDL-C to aim for, thresholds for ApoB have been less well-defined.
Recent guidelines from the National Lipid Association have clarified these goals4.
These Guidelines Are Based On Levels Of Risk.
But we always need to consider the timeframe over which that risk occurs, and the NLA guidelines, while helpful, I believe, still underestimate lifetime risk.
As I have grown fond of saying, “I am not interested in the next five years of risk; I am interested in the next 50”.
For near-term risk reduction, an ApoB of less than 60 mg/dl puts you at below the 5th percentile of the population and at a very low risk of heart attacks over your lifetime.
For those who are very serious and want to be aggressive about reducing their lifetime risk of future heart events, this is a good target.
If you already have extensive plaque in your coronary arteries or have had a prior heart attack, we may need to be even more aggressive.
Of course, if you do not wish to be as aggressive (which is completely fine), then looser ApoB targets are reasonable.
But it all depends on your individual risk and your attitude toward it.
Given that an ApoB of less than 60 mg/dl is at the 5th percentile for the population, by definition, 95% of the population will be above this level.
Some will be able to get down to this level with lifestyle measures.
Many won’t and will require medications to do so.
The question of whether to use medications to get to this low level is, as I said above, dependent on your individual level of risk and your attitude toward it.
But My Doctor Doesn’t Test For ApoB.
No problem.
You have two options.
Firstly, you can ask if it is possible to get your blood tests done in a hospital setting where ApoB levels are more routinely measured or whether you can access ApoB testing privately, but I would strongly recommend you test ApoB in consultation with a physician who is familiar with it.
Secondly, you can get a very good approximation of ApoB by calculating your Non-HDL cholesterol, which is available on your standard cholesterol panel.
Non-HDL cholesterol is frequently not listed on your standard cholesterol panel, but you can calculate it by subtracting your HDL-C from your Total Cholesterol.
With this figure you can reference it against the NLA guidelines above.
In general, however, most people who want to be aggressive about reducing risk will be aiming for a Non-HDL-C of at least <2.5 mmol/L or <100 mg/dL.
ApoB Is Not The Only Risk Factor For Atherosclerosis.
The retention of an ApoB particle in the artery wall is the signature of atherosclerosis.
That retention is much more likely in the context of other risk factors such as high blood pressure, insulin resistance, smoking, etc.
Therefore, to maximally reduce cardiovascular risk over your lifetime, you need to minimise your exposure to all of these factors for as long as possible.
But always remember that ApoB is central to this process and that we also have a range of options to take ApoB levels to pretty much any target we wish.
The choice is yours.
When You Are Ready, Here Is How We Can Help.
For an accessible and comprehensive overview of understanding and managing heart health, you can check out the best-selling book Heart. An Owner’s Guide.
For those based in Ireland, Dr Barrett works with a small number of clients to provide a comprehensive evaluation of cardiovascular risk and a tactical approach to maximally reducing that risk.
If you want to know more about a consultation with Dr Barrett, Click Here or on the button below.
In Case You Missed Them:
Ference BA, Kastelein JJP, Catapano AL. Lipids and Lipoproteins in 2020. JAMA. 2020;324(6):595–596.
Dose-Response Associations of Lipid Traits With Coronary Artery Disease and Mortality. JAMA Netw Open. 2024;7(1):e2352572.
Apolipoprotein B and Non-HDL Cholesterol Better Reflect Residual Risk Than LDL Cholesterol in Statin-Treated Patients. J Am Coll Cardiol. 2021 Mar 23;77(11):1439-1450.
https://www.lipid.org/sites/default/files/files/Role%20of%20apoB_Tearsheet%20FINAL.pdf
Why would you want to lower LDL in general when it is oxidised LDL that is partly responsible for arterial endothelial damage?Surely decreasing the underlying mechanism for ‘damaging’ LDL is a more effective strategy ie reducing mitochondrial dysfunction by decreasing insulin resistance ie adopting a LCHF or ketogenic diet.
And is the intimal damage not secondary to factors that damage the endothelial glycocalyx ie diet and shear factors within arteries resulting in damage/repair cycles hence the layered appearance of atheromatous plaques?Surely if it was a ‘cholesterol’ problem veins too would have atheromatous plaques?
So does Dr. Paddy have a study showing that manipulating ApoB can add a minute to your life? It's not about dying euboxic but prolonging a happy life.