Apolipoprotein B, commonly called apoB, is a protein that serves as the structural backbone of all the "bad" cholesterol-carrying particles in your blood. Think of apoB as a name tag—every particle that can contribute to plaque buildup in your arteries carries exactly one apoB molecule on its surface. This includes LDL particles (the main carriers of "bad" cholesterol), VLDL particles (which carry triglycerides), and lipoprotein(a) particles.[1][2]

Because each atherogenic (artery-damaging) particle contains exactly one apoB molecule, measuring apoB gives you a direct count of the total number of dangerous particles circulating in your bloodstream.[1] This is fundamentally different from measuring LDL cholesterol, which tells you how much (for the weight of the) cholesterol is being carried inside those particles—not how many particles there are.

This distinction matters enormously. Imagine two people with the same LDL cholesterol level of 100 mg/dL. One person might have 1,000 large LDL particles, each carrying a lot of cholesterol. The other might have 1,500 smaller particles, each carrying less cholesterol. Both have the same total cholesterol cargo, but the second person has 50% more particles—and therefore 50% more opportunities for those particles to get trapped in artery walls and cause damage.[3][4]

The Particle Number Hypothesis: Why Counting Matters More Than Measuring Cargo

For decades, cardiovascular medicine focused on measuring the cholesterol content of lipoproteins—LDL cholesterol, HDL cholesterol, and triglycerides. However, a growing body of evidence now supports what scientists call the "particle number hypothesis": it's the number of atherogenic particles, not the amount of cholesterol they carry, that primarily determines your cardiovascular risk.[5][6]

Here's why this makes biological sense. Atherosclerosis—the buildup of fatty plaques in your arteries—begins when apoB-containing particles penetrate the inner lining of your artery walls and become trapped there. Once trapped, these particles trigger an inflammatory response that leads to plaque formation.[2][7] The key insight is that each particle, regardless of its size or cholesterol content, has roughly the same probability of entering and getting stuck in the artery wall. Therefore, the more particles you have circulating, the more particles will become trapped, and the faster atherosclerosis will progress.[2]

A landmark study combining data from nearly 430,000 people demonstrated this principle clearly. When researchers looked at apoB, non-HDL cholesterol, and triglycerides together, only apoB remained significantly associated with heart attack risk. Once the number of apoB particles was accounted for, neither the cholesterol content nor the triglyceride content of those particles provided any additional information about risk.[5]

ApoB is a Proven Causal Factor in Heart Disease

Unlike some biomarkers that merely correlate with disease, apoB has been shown through genetic studies to actually cause cardiovascular disease. This distinction is crucial because it means that lowering apoB will reduce your risk—not just predict it.[8][9]

One particularly compelling Mendelian randomization study found that genetically elevated apoB shortens lifespan by approximately 2 years and increases the risk of heart disease in first-degree relatives.[10] This genetic evidence provides strong support for the concept that lowering apoB throughout life will translate into meaningful reductions in cardiovascular events and improved longevity.

Frequently asked questions:

How is ApoB Measured?

An apoB test is a simple blood test that directly measures the number of atherogenic (“bad”) cholesterol particles in your blood. You don’t need to fast for it, and the test is highly standardized and reliable across laboratories. Compared with LDL cholesterol, apoB tends to be more consistent from test to test and gives a more direct picture of your cardiovascular risk. [1][12]

What Should My ApoB Be?

The 2024 National Lipid Association Expert Clinical Consensus provides the following apoB thresholds for cardiovascular risk assessment:[1]

• Less than 90 mg/dL: Desirable for people at borderline to intermediate cardiovascular risk

• Less than 70 mg/dL: Target for people at high cardiovascular risk

• Less than 60 mg/dL: Target for people at very high cardiovascular risk (such as those with established heart disease, diabetes with additional risk factors, or familial hypercholesterolemia)

For context, the median apoB level in the general adult population is approximately 90-100 mg/dL, and the 90th percentile (meaning only 10% of people have higher levels) is approximately 130 mg/dL.[1]

The European Society of Cardiology has endorsed apoB as a more accurate marker of cardiovascular risk than LDL cholesterol since 2019, and recommends apoB targets of less than 65 mg/dL for high-risk patients and less than 55 mg/dL for very high-risk patients.[3]

Why ApoB is Superior to LDL Cholesterol?

While LDL cholesterol remains the most commonly used lipid measurement, substantial evidence now shows that apoB is a more accurate marker of cardiovascular risk than LDL cholesterol, particularly in certain patient populations.[3][1]

The 2024 National Lipid Association consensus statement summarizes the key advantages of apoB:[1]

1. ApoB and non-HDL cholesterol stratify cardiovascular risk more accurately than LDL cholesterol, both before and during treatment with lipid-lowering therapy

2. When there is discordance between apoB and LDL cholesterol, apoB is the strongest predictor of cardiovascular risk

3. ApoB provides important additional prognostic information beyond LDL cholesterol across the entire LDL cholesterol spectrum—even at low LDL cholesterol levels

A large study from the Copenhagen population studies found that 1 in 10 people in the general population have "excess apoB"—meaning their apoB level is higher than would be expected based on their LDL cholesterol. These individuals had approximately a 50% higher risk of heart attack and a 35% higher risk of cardiovascular disease compared to what would be predicted from their LDL cholesterol alone.[13]

How Can You Lower Your ApoB?

ApoB responds well to both lifestyle changes and medications, making it an actionable target for reducing atherosclerotic risk. Weight loss of about 6–12% can meaningfully lower apoB, and dietary strategies that help include replacing refined carbohydrates with monounsaturated fats, increasing omega-3s, adding soluble fiber and plant sterols, eating nuts regularly, and following a Mediterranean-style diet. Exercise also lowers apoB, especially when combined with weight loss and healthy eating.[1][4][17]

Medications That Lower ApoB

All medications that lower LDL cholesterol also lower apoB by reducing the number of atherogenic particles in the blood. Statins are the cornerstone of therapy and typically lower apoB by 25–50%; ezetimibe can lower it another 15–20%, and PCSK9 inhibitors or inclisiran can reduce apoB by 40–50% on top of statins. Bempedoic acid lowers apoB by about 15–25%, bile acid sequestrants by up to 20%, and for people with severe genetic elevations such as familial hypercholesterolemia, additional therapies like lomitapide or evinacumab may be used. [1][18][4][19]

References

1. Role of Apolipoprotein B in the Clinical Management of Cardiovascular Risk in Adults: An Expert Clinical Consensus From the National Lipid Association. Soffer DE, Marston NA, Maki KC, et al. Journal of Clinical Lipidology. 2024 Sep-Oct;18(5):e647-e663. doi:10.1016/j.jacl.2024.08.013.

2. Apolipoprotein B-Containing Lipoproteins in Atherogenesis. Borén J, Packard CJ, Binder CJ. Nature Reviews. Cardiology. 2025;22(6):399-413. doi:10.1038/s41569-024-01111-0.

3. Physiological Bases for the Superiority of Apolipoprotein B Over Low-Density Lipoprotein Cholesterol and Non-High-Density Lipoprotein Cholesterol as a Marker of Cardiovascular Risk. Glavinovic T, Thanassoulis G, de Graaf J, et al. Journal of the American Heart Association. 2022;11(20):e025858. doi:10.1161/JAHA.122.025858.

4. Apolipoprotein B Particles and Cardiovascular Disease: A Narrative Review. Sniderman AD, Thanassoulis G, Glavinovic T, et al. JAMA Cardiology. 2019;4(12):1287-1295. doi:10.1001/jamacardio.2019.3780.

5. Association of Apolipoprotein B–Containing Lipoproteins and Risk of Myocardial Infarction in Individuals With and Without Atherosclerosis: Distinguishing Between Particle Concentration, Type, and Content. Marston NA, Giugliano RP, Melloni GEM, et al. JAMA Cardiology. 2022;7(3):250-256. doi:10.1001/jamacardio.2021.5083.

6. ApoB-containing Lipoproteins: Count, Type, Size, and Risk of Coronary Artery Disease. Morze J, Melloni GEM, Wittenbecher C, et al. European Heart Journal. 2025;46(27):2691-2701. doi:10.1093/eurheartj/ehaf207.

7. Apolipoprotein B Compared With Low-Density Lipoprotein Cholesterol in the Atherosclerotic Cardiovascular Diseases Risk Assessment. Galimberti F, Casula M, Olmastroni E. Pharmacological Research. 2023;195:106873. doi:10.1016/j.phrs.2023.106873.

8. Evaluating the Relationship Between Circulating Lipoprotein Lipids and Apolipoproteins With Risk of Coronary Heart Disease: A Multivariable Mendelian Randomisation Analysis. Richardson TG, Sanderson E, Palmer TM, et al. PLoS Medicine. 2020;17(3):e1003062. doi:10.1371/journal.pmed.1003062.

9. High-Throughput Multivariable Mendelian Randomization Analysis Prioritizes Apolipoprotein B as Key Lipid Risk Factor for Coronary Artery Disease. Zuber V, Gill D, Ala-Korpela M, et al. International Journal of Epidemiology. 2021;50(3):893-901. doi:10.1093/ije/dyaa216.

10. Effects of Apolipoprotein B on Lifespan and Risks of Major Diseases Including Type 2 Diabetes: A Mendelian Randomisation Analysis Using Outcomes in First-Degree Relatives. Richardson TG, Wang Q, Sanderson E, et al. The Lancet. Healthy Longevity. 2021;2(6):e317-e326. doi:10.1016/S2666-7568(21)00086-6.

11. Dose-Response Associations of Lipid Traits With Coronary Artery Disease and Mortality. Yang G, Mason AM, Wood AM, Schooling CM, Burgess S. JAMA Network Open. 2024;7(1):e2352572. doi:10.1001/jamanetworkopen.2023.52572.

12. Beyond Low-Density Lipoprotein Cholesterol: Defining the Role of Low-Density Lipoprotein Heterogeneity in Coronary Artery Disease. Mudd JO, Borlaug BA, Johnston PV, et al. Journal of the American College of Cardiology. 2007;50(18):1735-41. doi:10.1016/j.jacc.2007.07.045.

13. Excess Apolipoprotein B and Cardiovascular Risk in Women and Men. Johannesen CDL, Langsted A, Nordestgaard BG, Mortensen MB. Journal of the American College of Cardiology. 2024;83(23):2262-2273. doi:10.1016/j.jacc.2024.03.423.

14. Discordance Between Serum Cholesterol Concentration and Atherogenic Lipoprotein Particle Number in People With Metabolic Disease: A Systematic Review. Witt C, Renfroe LG, Lyons TS. Diabetes, Obesity & Metabolism. 2025;27(6):2940-2954. doi:10.1111/dom.16335.

15. Individual Variation in the Distribution of Apolipoprotein B Levels Across the Spectrum of LDL-C or Non–HDL-C Levels. Sayed A, Peterson ED, Virani SS, Sniderman AD, Navar AM. JAMA Cardiology. 2024;9(8):741-747. doi:10.1001/jamacardio.2024.1310.

16. Apolipoprotein B and Non-HDL Cholesterol Better Reflect Residual Risk Than LDL Cholesterol in Statin-Treated Patients. Johannesen CDL, Mortensen MB, Langsted A, Nordestgaard BG. Journal of the American College of Cardiology. 2021;77(11):1439-1450. doi:10.1016/j.jacc.2021.01.027.

17. Nutritional Management of hyperapoB. Lamantia V, Sniderman A, Faraj M. Nutrition Research Reviews. 2016;29(2):202-233. doi:10.1017/S0954422416000147.

18. The Evolving Landscape of Targets for Lipid Lowering: From Molecular Mechanisms to Translational Implications. Ballantyne CM, Norata GD. European Heart Journal. 2025;:ehaf606. doi:10.1093/eurheartj/ehaf606.

19. New and Emerging Therapies for Reduction of LDL-Cholesterol and Apolipoprotein B: JACC Focus Seminar 1/4. Nurmohamed NS, Navar AM, Kastelein JJP. Journal of the American College of Cardiology. 2021;77(12):1564-1575. doi:10.1016/j.jacc.2020.11.079.