Measuring ‘Bad Cholesterol’ Doesn’t Tell the Whole Story

Over the years, evaluation cholesterol risk was built around a simple idea: To lower “bad” cholesterol, reduce your chances of a heart attack. A test in the middle of that process measures the amount of low-density lipoprotein, or LDL cholesterol, circulating in the blood. It has changed everything from medical guidelines to the widespread use of statins, drugs that lower LDL.

It’s working. Lowering LDL cholesterol reduces the risk of heart attack, stroke, and early death. But it doesn’t tell the whole story.

The LDL cholesterol test measures the amount of cholesterol within the small lipoprotein particles circulating in the blood. LDL particles that contain cholesterol can clog arteries, forming plaques that can block blood flow. Because the test measures the amount of cholesterol absorbed, not just the number of LDL particles, two people can have the same level of LDL cholesterol but the number of particles, and therefore different levels of risk.

This difference has led researchers to pursue a different method of measuring risk. Apolipoprotein B, or apoB, indicates the amount of cholesterol particles in the blood rather than the amount of cholesterol it contains. Many studies show that it is an accurate way to determine who is at risk and who is not.

In March 2026, the American Heart Association and the American College of Cardiology recognized this. Their updated cholesterol guidelines accepted apoB as the most accurate marker, in line with previous European recommendations. But they stopped short of accepting apoB as a first-line test.

“They review the evidence and put apoB higher, but the real rules of the road continue to prioritize LDL,” says Allan Sniderman, a cardiologist at McGill University.

Sniderman was a writer on 2026 JAMA modeling A study that analyzed lifetime outcomes for nearly 250,000 US adults eligible for statin therapy. By comparing LDL cholesterol, non-HDL cholesterol, and apoB, the study found that using apoB to guide treatment decisions can prevent heart attacks and strokes better than current methods, while remaining cost-effective.

ApoB testing can be done through a routine blood test. So why hasn’t it entered routine care? Not even in Europe, where the guidelines have proven useful over the years.

Part of the answer is inertia. Over the years, LDL cholesterol has been a scientific success story and a public health success story. It’s simple, familiar, and directly related to the drugs that work.

“For 50 years, LDL cholesterol was found to be amazing,” says Sniderman. “It’s not a good sign.

Børge Nordestgaard, president of the European Atherosclerosis Society, agrees that LDL cholesterol remains among the causes. “The evidence is overwhelming and overwhelming,” he said. “Statins reduce heart attacks, strokes, and early death by lowering LDL cholesterol.”

That success helped shape a powerful narrative: LDL is the “bad cholesterol,” and lowering it saves lives. But that simplicity has also reduced the perception of risk.

“The result is that patients and doctors have little or no knowledge about apoB,” says Sniderman.

Recent studies show that the cholesterol picture is very difficult, especially in people who are already taking statins. Previous research led by Nordestgaard has shown that in treated patients, high levels of apolipoprotein B and non-HDL cholesterol are associated with an increased risk of heart disease and death, while LDL cholesterol is not. ApoB, in particular, emerged as the most accurate marker.

For Kausik Ray, a cardiologist at Imperial College London, the problem is not choosing which pen, but understanding what each person takes, and what they miss.

“We’re not interested in cholesterol for its own sake,” says Ray. “We’re trying to prevent heart disease and stroke.”