FOR DECADES, ASSESSING cholesterol risk has been built around a simple idea: Lower “bad” cholesterol, lower your chance of a heart attack. The test at the center of that approach measures how much low-density lipoprotein, or LDL cholesterol, is circulating in part of the blood. It has shaped everything from clinical guidelines to the widespread use of statins, medications that reduce LDL.
It works. Lowering LDL cholesterol reduces heart attacks, strokes, and early death. But it doesn’t tell the whole story.
The LDL cholesterol test measures the amount of cholesterol inside the low-density lipoprotein particles circulating in the bloodstream. Those LDL particles containing the cholesterol can get trapped in artery walls, forming plaques that can eventually block blood flow. As the test measures the amount of cholesterol being carried, not the number of LDL particles themselves, two people can have the same LDL cholesterol level but very different numbers of particles, and therefore different levels of risk.
That gap has pushed researchers toward a different way of measuring risk. Apolipoprotein B, or apoB, reflects the total number of cholesterol-carrying particles in the blood rather than how much cholesterol they contain. A growing body of research suggests it’s a more accurate way of identifying who is at risk and who’s not.
