Apolipoproteins are the main protein that form lipoproteins — these transport fat, like cholesterol, around your body. There are two main types — apolipoprotein A1 and apolipoprotein B. Certain lifestyle factors like diet can elevate or lower your levels, increasing your risk of developing heart disease. A healthy lifestyle can help you manage your apolipoprotein levels.

Medically reviewed by Dr Nicole Harris, MBChB MRCGP

What are apolipoproteins?

Apolipoproteins are proteins that bind to lipids (fats), like cholesterol. Fats can’t travel in your blood on their own, so these proteins provide them with structure so that they can be transported. There’s a range of different types of apolipoproteins — like apolipoprotein A1 and apolipoprotein B.

What is apolipoprotein A1?

Apolipoprotein A1 (apo A1) is the main protein found in high-density lipoprotein (HDL) cholesterol — this type of cholesterol is linked to a lower risk of heart disease. 

This is because HDL particles carry excess cholesterol from your arteries to your liver, where it can be removed from your body. This process helps to stop excess fat from building up on the walls of your arteries, protecting you from heart disease.

The higher your apo A1 result, the more HDL particles you have and the lower your risk of heart disease. While if your HDL levels are too low, your risk of heart disease increases. Low apo A1 levels are also linked to an increased risk of depression in women.

Your apo A1 levels are considered a better predictor of your risk of heart disease than measuring the amount of cholesterol in your HDL particles. 

What causes low apolipoprotein A1 levels?

Low apo A1 levels are usually caused by:

  • an unhealthy diet
  • being overweight
  • lack of exercise
  • smoking
  • uncontrolled diabetes
  • a rare genetic condition called hypoalphalipoproteinemia

What is apolipoprotein B?

Apolipoprotein B (apo B) is the main type of protein found in lipoproteins, like low-density lipoprotein (LDL) cholesterol, and ultra low-density lipoproteins (chylomicrons).

High levels of apo B are linked to an increased risk of heart disease — even if your LDL cholesterol levels are in a normal range. 

What is the function of apo B?

Apo B helps to transport:

  • LDL cholesterol — also known as bad cholesterol
  • ultra low-density lipoproteins
  • intermediate-density lipoprotein (IDL)
  • lipoprotein(a) — Lp(a)

Each of these lipoproteins contain one apo B particle. So your apo B levels can tell you the full amount of these lipoproteins in your blood. This is why your apo B levels are considered a better predictor of your risk of heart disease when compared to just measuring LDL cholesterol.  

How does apo B affect your heart health?

Lipoproteins containing apo B, like LDL cholesterol, are more likely to enter the walls of your arteries — they’re atherogenic. This process could lead to the buildup of plaque on your arteries (atherosclerosis), restricting your blood flow.

If your apo B levels are raised, your risk of heart disease increases — like your risk of heart attack and stroke.

What causes high apo B levels?

Unhealthy lifestyle habits can increase your apo B levels. Common risk factors include:

  • eating foods high in saturated and trans fats — like butter, margarine, cream, and sausages
  • lack of exercise
  • carrying excess weight
  • diabetes
  • hypothyroidism
  • a genetic condition called familial hypercholesterolaemia — your body is unable to remove LDL cholesterol from your blood.

What is your apoB/apo A1 ratio?

Your apoB/apo A1 ratio is the calculation of your apo B levels divided by your apo A1 levels. A higher ratio is linked to an increased risk of heart disease.

Your apolipoprotein ratio is considered a better predictor of your risk of heart disease than individual apolipoprotein results alone.

The apoB/apo A1 ratio is also sometimes used to guide the effectiveness of treatment with medications that help lower LDL cholesterol.

How to improve your apolipoprotein levels

Healthy lifestyle habits can help increase your apo A1 levels and lower your apo B levels. These include:

  • eating high-fibre foods — like fruits, vegetables, and whole grains
  • eating oily fish rich in omega-3s — like salmon and mackerel 
  • eating lean sources of protein — like chicken, fish, and legumes
  • limiting foods high in saturated and trans fats — like fast and fried food
  • losing any excess weight
  • not drinking more than 14 units of alcohol a week
  • not smoking
  • moderate-intensity exercise — like brisk walking or cycling, for at least 150 minutes a week
  • high-intensity exercise — like running or swimming, for at least 75 minutes a week

These healthy lifestyle habits can help reduce your risk of developing heart disease. 

How to test your apo A1 and apo B levels

A blood test can tell you your apolipoprotein levels, but this test isn’t very common yet. You can check with your GP or you have the option of doing a home apo A1 and apo B blood test. 

References

Dansinger, M. L., Williams, P. T., Superko, H. R., & Schaefer, E. J. (2019). Effects of weight change on apolipoprotein B-containing emerging atherosclerotic cardiovascular disease (ASCVD) risk factors. Lipids in health and disease, 18(1), 1-10.

Del Gobbo, L. C., Falk, M. C., Feldman, R., Lewis, K., & Mozaffarian, D. (2015). Effects of tree nuts on blood lipids, apolipoproteins, and blood pressure: systematic review, meta-analysis, and dose-response of 61 controlled intervention trials. The American journal of clinical nutrition, 102(6), 1347-1356.

Richard, C., Couture, P., Ooi, E. M., Tremblay, A. J., Desroches, S., Charest, A., ... & Lamarche, B. (2014). Effect of Mediterranean diet with and without weight loss on apolipoprotein B100 metabolism in men with metabolic syndrome. Arteriosclerosis, thrombosis, and vascular biology, 34(2), 433-438.

Richardson, T. G., Sanderson, E., Palmer, T. M., Ala-Korpela, M., Ference, B. A., Davey Smith, G., & Holmes, M. V. (2020). Evaluating the relationship between circulating lipoprotein lipids and apolipoproteins with risk of coronary heart disease: A multivariable Mendelian randomisation analysis.PLoS medicine,17(3), e1003062.

Walldius, G., & Jungner, I. (2004). Apolipoprotein B and apolipoprotein A‐I: risk indicators of coronary heart disease and targets for lipid‐modifying therapy. Journal of internal medicine, 255(2), 188-205.

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Olivia Hunt

Written by Olivia Hunt

24th Jun 2021 • 6 min read