High-density lipoprotein (HDL), which has been referred to as “good cholesterol” by medical experts, is being re-examined after a new study questioned the benefits of this cholesterol type across racial lines.
Researchers at the Oregon Health & Science University’s Knight Cardiovascular Institute analyzed 23,901 medical profiles from a Reasons for Geographic and Racial Differences in Stroke Study (REGARDS) and compared the risk factors of cardiovascular events happening to middle-aged Black and White patients.
The study was funded by the National Institutes of Health (NIH), a medical research agency under the U.S. Department of Health and Human Services and was published in the Journal of the American College of Cardiology on Monday, Nov. 21.
Of the thousands of REGARDS participants analyzed, researchers narrowed down their findings to patients who had enrolled in the study from 2003 and 2007, and then they followed the patients’ health records over a 10- to 11-year period.
Black and White study participants reportedly had similar cholesterol levels and underlying risk factors for heart disease, including diabetes, high blood pressure and smoking.
Over the decade-long period, researchers found that 664 Black patients and 951 White patients had experienced a heart attack or a heart attack-related death.
“It’s been well accepted that low HDL cholesterol levels are detrimental, regardless of race. Our research tested those assumptions,” Nathalie Pamir, the study’s senior author, wrote in a statement, according to the NIH.
“The goal was to understand this long-established link that labels HDL as the beneficial cholesterol, and if that’s true for all ethnicities,” Pamir, who’s an associate professor of medicine at Oregon Health & Science University, Portland, added.
High-density lipoprotein has reportedly been viewed favorably, because it has been shown to absorb cholesterol in the blood and carry it back to the liver, according to the U.S. Centers for Disease Control and Prevention (CDC).
The liver reportedly flushes cholesterol from the body, which can lower a person’s chance of heart disease and stroke if there are high HDL cholesterol levels.
Low-density lipoprotein (LDL), also known as “bad cholesterol,” makes up most of the body’s cholesterol, according to the CDC.
Having high rates of LDL cholesterol has been associated with an increased risk of heart disease and stroke.
“When your body has too much LDL cholesterol, the LDL cholesterol can build up on the walls of your blood vessels,” the CDC wrote in an online cholesterol explainer. “This buildup is called ‘plaque.’”
The new study’s analysis of the REGARDS data confirmed that high levels of LDL cholesterol and triglycerides (neutral fats) resulted in “modestly increased risks for cardiovascular disease,” according to the NIH.
Low levels of HDL cholesterol were found to have increased cardiovascular disease risk for White patients, but the same wasn’t true for Black patients, according to the study.
At the same time, the study determined that high levels of HDL cholesterol aren’t always associated with a lower chance of cardiovascular events — regardless of racial group.
Authors of the study conclude that cardiovascular disease risk calculators that utilize HDL cholesterol level readings could return an inaccurate prediction for Black patients.
“HDL cholesterol has long been an enigmatic risk factor for cardiovascular disease,” Sean Coady, deputy branch chief of epidemiology at the National Heart, Lung, and Blood Institute’s Division of Cardiovascular Sciences, wrote in a statement.
“The findings suggest that a deeper dive into the epidemiology of lipid metabolism is warranted,” Coady continued. “Especially in terms of how race may modify or mediate these relationships.”
The fully published study can be found on Journal of the American College of Cardiology’s website at jacc.org.