What are Apolipoproteins?

It has been clear for awhile that traditional lipid panels may not be the best screening tool for cardiovascular health. In the PROVE-IT TIMI 22 trial, 22.7% of patients still had major cardiovascular events (MCVE) at 2 years of follow-up, despite having normal LDL-C levels. Apolipoprotein measurements may give us better insight in to our individual cardiovascular risk- but what are they?

In order to understand what Apolipoproteins are and how they effect our longevity, we need to understand their relationship to traditional cholesterol measurements- LDL, VLDL and HDL. Apolipoproteins are proteins that bind and transport or carry these lipids (like Cholesterol and thus LDL, VLDL). Together, the apolipoprotein and lipid form a lipoprotein. This lipoprotein is part lipid, part protein.

Apolipoprotein B is primarily responsible for transporting cholesterol and other lipids throughout the body. There are 2 types of Apolipoprotein B- apoB-100 and Apob-48. ApoB-100 is found in low-density lipoprotein (LDL) particles or “bad” cholesterol. ApoB-48 is found in chylomicrons which are responsible for transporting dietary fats from the intestine to the rest of the body. The primary function of aboB-100 is to carry our LDL and VLDL cholesterol from the liver to various tissues and organs. However, when LDL cholesterol is too high, the accumulation can lead to plaques in arteries. These plaques narrow and harden and can increase the risk of heart attack and stroke.

Research has shown that apoB-100 levels are a more accurate predictor of cardiovascular risk than simply measuring LDL cholesterol levels. This is because LDL cholesterol is only measured from a calculation, it is not directly measured. There can be very high variability in this measurement. Since we know apoB-100 carries one of the “bad” lipoproteins (giving a ratio of 1:1), this method of measuring for cardiovascular risk may be more accurate. Studies have also shown that people with lower levels of apoB tend to have healthier cholesterol profiles and a reduced risk of developing cardiovascular disease.

ApoA1 transports HDL or “good”cholesterol. HDL removes excess cholesterol from the arteries and transports it back to the liver for excretion. The ratio of apoB/apoA1 shows the balance between these two opposing forces and has been proven to be an accurate indicator of CVD risk. The greater the ratio, the more cholesterol is circulating in the plasma and thus being deposited into the arterial wall.

We now also know that menopause and drops in estradiol have a significant effect on our cardiovascular risk by decreasing HDL and increasing apolipoprotein B.

If you find you have a high ratio of ApoB:ApoA, or a high ApoB, it’s best to lower the numbers as much as possible. We can decrease our ApoB and LDL levels by the usual healthy measures: not smoking, eating a healthy diet, exercising and when indicated, adding on estradiol.

We all want to live a long and healthy life. Apolipoprotein screening may be one test that can help you improve your future cardiovascular risk and thus live your best life.

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