'Good' Cholesterol May Not Actually Be Good

A new study is countering the idea that "good cholesterol" can protect patients from heart disease.

The Journal of the American College of Cardiology shared analysis of data on Monday (November 21) from nearly 24,000 American adults in relation to high levels of HDL preventing heart disease.

The study, which was co-funded by the National Institutes of Health, found that too little HDL cholesterol was associated with an increased risk of heart disease in white adults, but not Black adults.

Researchers were stunned by the results after initially designing the study, which aimed to understand how cholesterol levels would affect future risks in Black and white middle-aged adults without heart disease.

Prior research on "good" cholesterol and heart disease had mostly consisted among white adults, according to the study.

“I did not expect high levels of HDL would not be protective,” said the study’s senior author, Nathalie Pamir, an associate professor of cardiovascular medicine in the Oregon Health and Science University School of Medicine, via NBC News. “And I certainly did not expect low levels to have no predictive value for Black adults.”

The research is the latest among growing evidence that high HDL, known commonly as "good cholesterol," may not protect against heart disease as previously believed, though many people may not be aware of the new data.

“Those of us with high HDL have been getting a pat on the back from our doctors,” said Pamir, who also serves as a researcher at the Center for Preventive Cardiology at OHSU’s Knight Cardiovascular Institute, via NBC News. “We’ve been told your HDL is good so don’t worry. You’re protected.”

Low density lipoprotein, also known commonly as LDL, contributes to fatty buildups in the arteries, which creates a serious risk of heart attack and stroke.

HDL has long been believed to serve as a protective against LDL as it carries cholesterol to the liver to be disposed of.

The new data suggests that HDL, instead, only adds to the total cholesterol number.

“It’s still cholesterol at the end of the day,” Pamir said via NBC News. “More and more studies are coming out showing that HDL levels above 80 are detrimental with regards to cardiovascular outcomes.”