This blood test may predict heart disease better than LDL cholesterol, some doctors say

“Bad” cholesterol, or LDL, is a major risk factor for heart disease and most people are screened for it as part of their annual physicals.

There is another marker in the blood that may be a better indicator of heart disease risk, a recent comprehensive study suggests. But it is not part of routine blood tests.

Apolipoprotein B (apoB) is a protein that attaches to harmful fat particles in the blood. The apoB protein is found on the surface of harmful lipoproteins like low-density lipoprotein, or LDL, which contribute to heart disease. Since each of the harmful particles contains an apoB molecule, searching for it essentially captures the total number of harmful plaque-producing compounds.

Doctors usually monitor LDL closely because it is the main indicator of whether a person is at risk of developing heart disease. If it is high, they may recommend lifestyle changes or starting medications to reduce it.

Cholesterol is a waxy, fatty substance that the body uses to build cells and make hormones such as testosterone and estrogen. A blood lipid panel usually gives an overview of the total cholesterol level in the blood, including LDL, very low density lipoprotein (VLDL), and high density lipoprotein (HDL). The blood test also checks for triglycerides, another type of fat in the blood that can contribute to heart disease.

LDL and VLDL can get stuck in the walls of an artery, ultimately causing the vessel to narrow and contributing to heart disease, said Dr. Ann Marie Navar, a preventative cardiologist at UT Southwestern Medical Center in Dallas.

“Cholesterol is not dissolved in the blood like sugar and sweet tea. It is contained in things called lipoproteins,” Navar said.

The problem is that a normal LDL level doesn’t necessarily mean you’re safe. Some people may have undetected high apoB – a phenomenon called discordance. Factors such as being overweight, diabetes or high triglyceride levels make this mismatch between normal LDL and high apoB more likely.

Current American Heart Association guidelines do not recommend routine testing for apoB as part of cholesterol screening except for certain patients with elevated triglycerides.

Navar, however, believes that all adults should be screened, and she regularly checks her patients for apoB.

Dr. Samia Mora, cardiologist and director of the Center for Lipid Metabolomics at Brigham and Women’s Hospital, recommends testing for apoB at least once to ensure it matches the LDL screening results.

How is apoB tested?

Heart disease is the leading cause of death among men and women in the United States

Hardening of the arteries caused by a buildup of plaque-producing particles is best assessed using the apoB test, according to Dr. Thomas Dayspring, a member of the National Lipid Association and renowned cholesterol expert.

“ApoB is by far the best metric that every human being should be tested for when doing their cardiovascular risk assessment,” Dayspring said last fall during an appearance on the “Proof with Simon Hill” podcast.

An apoB test directly looks at the number of artery-clogging particles in the blood. “LDL cholesterol tells me how much cholesterol is carried by LDL particles, and apoB tells me how many LDL particles I have,” Mora said.

Dr. Jeffrey Berger, a preventative cardiologist at NYU Langone, said that “apoB provides a convenient and comprehensive way to fundamentally assess cholesterol burden,” which is involved in bad cholesterol accumulation and plaque formation.

However, fewer than 1% of adults in the United States have been tested for the blood protein, according to a 2024 study sponsored by drugmaker Regeneron and published in the American Journal of Preventive Cardiology.

ApoB tests are popular among health influencers and increasingly touted in the commercial blood testing market. Recently, salad chain Sweetgreen — which has partnered with anti-seed oil influencers — launched a collaboration with testing company Function Health and is promoting apoB testing on its menus.

Dr. Michael Shapiro, a preventive cardiologist and chair of the American Heart Association Council on Lipidology, Lipoproteins, Metabolism and Thrombosis, said he typically uses an apoB test in some patients.

“I think the best use case is when you’re treating someone with a lipid-lowering treatment,” he said, referring to drugs such as statins, which are taken to lower cholesterol. “Maybe you’ve gotten them to the LDL cholesterol level that you were trying to get them to and now you want to determine if they’ve really reached the goal that you want them to achieve.”

In some cases, insurance may cover the test. Otherwise, it usually costs around $70 at a lab.

There are no clear guidelines on target apoB levels. In healthy people, apoB values ​​below 90 mg/dL are generally considered acceptable, with some arguing that lower goals, closer to 70 mg/dL, may be more optimal for preventing heart disease.

For Navar, the real concern is that people aren’t getting their cholesterol levels checked at all. Nearly 25% of eligible adults have not been screened in the past five years, according to a Johns Hopkins University study.