Is apoB More Important to Measure than Cholesterol?

Low density lipoprotein (LDL) cholesterol—also known as the “bad” cholesterol—is often used as an indicator of heart disease and stroke risks. But some emerging evidence suggests that a protein named apolipoprotein b (apoB) is an even more accurate marker that can identify potential high-risk patients.

apoB is a major structural protein found in LDL, and it helps to transport fat and cholesterol throughout the body. Lipoproteins that contain apoB, such as bad cholesterol, are particularly dangerous because they can penetrate the walls of arteries.

These apoB particles can lead to plaque buildup in the arteries, increasing the risk of heart disease and stroke, according to Nicole Harkin, MD, FACC, a cardiologist and the founder of Whole Heart Cardiology.

“When we measure apoB, we’re actually counting all of these particles that cause plaque buildup, and this is a much more accurate way of determining cardiovascular risk due to cholesterol,” Harkin told Verywell.

Furthermore, apoB-containing lipoproteins inside the artery walls can attract immune cells, causing further damage, said Kevin Jon Williams, MD, a professor of cardiovascular sciences and medicine at the Lewis Katz School of Medicine at Temple University in Philadelphia.

“Dead cells, cholesterol deposits, and cells of the immune system accumulate in the plaque. This plaque can become weakened and erode or rupture, causing a heart attack or stroke,” Williams said.

Why Might apoB Be a Better Predictor of Heart Disease Risk?

A standard lipid panel generally includes four things: total cholesterol, high density lipoprotein (HDL) cholesterol, LDL cholesterol, and triglycerides. The cholesterol carried in plasma is a mix of other lipoproteins, many of which do not have an association with heart disease.

While LDL levels can indicate heart disease risks, they’re not always consistent because they can vary in size and density. But every LDL particle carries exactly one molecule of apoB, making apoB a more accurate predictor of heart disease risks.

“Larger LDL particles carry more cholesterol but have a harder time getting into the arterial wall and getting stuck. Smaller LDL particles each carry less cholesterol but have an easier time getting into the artery wall and staying there. So the harm from each LDL particle—big or small—is about the same,” Williams said.

Should You Test for ApoB Then?

While apoB is not included in a standard lipid panel test, Williams said it’s a good idea to have your apoB levels measured at least once to see if it’s consistent with your cholesterol levels, especially if you have a family history of heart disease.

Harkin added that individuals with insulin resistance, type 2 diabetes, obesity, elevated triglycerides, or metabolic syndrome are particularly at risk for heart disease, and they should be more concerned about their apoB levels.

“While it’s not covered by insurance, it’s inexpensive to add on, so it’s not something that should be out of reach for most people,” Harkin said.

LDL cholesterol is still a “very good marker” for heart disease risk, though, according to Harkin.

“We have decades of literature showing you can lower risk if you lower LDL. apoB is a more precise measure, which may allow us to better optimize risk assessment and management due to elevated cholesterol. We’re starting to build up that body of evidence,” Harkin said.