Federal guidelines say to aim for high HDL cholesterol levels—known as the “good” kind—to protect your heart.
But men with high HDL levels may actually be more likely to die prematurely, a new study in the Clinical Journal of the American Society of Nephrology suggests.
Researchers tracked more than 1.7 million men for nearly a decade. They found that those with HDL levels above 50 milligrams per deciliter (mg/dL) were significantly more likely to die during the study than those with levels between 25 to 50 mg/dL.
(Guys with levels below 25 mg/dL were also more likely to die than those in the middle range.)
The National Institutes for Health (NIH) says that anything above 59 mg/dL protects you from heart disease. So these findings seem to be challenging some long-held beliefs.
HDL is considered “good” because it prevents LDL (“bad”) cholesterol from building up in your arteries and narrowing them, which can lead to clots and subsequent heart attacks and strokes.
So why did the high-HDL men die sooner in the study? The researchers aren’t sure, but that group of men also had higher levels of inflammation, says lead researcher Ziyad Al-Aly, M.D., of the Veterans Affairs St. Louis Health Care System.
Chronic inflammation can be killer, contributing to deadly conditions like heart disease and cancer.
Still, the scientists don’t know if high HDL somehow causes inflammation. More research is needed to figure out what—if anything—is going on.
Because this data is so new and uncertain, it doesn’t change the HDL guidelines laid out by the NIH, says Prediman Krishan Shah, M.D., a cardiology advisor.
But it’s a good reminder that you can’t rely too much on any one number to determine your health.
In fact, the American Heart Association and the American College of Cardiology recently changed their reccommendations for statin therapy for high cholesterol away from a certain number in favor of a multi-faceted approach that takes into account your 10-year risk of developing heart disease.