HDL or ‘good’ cholesterol may not affect heart health, medical study suggests
High-density lipoprotein (HDL), which medical experts call “good cholesterol,” is being reexamined after a new study questioned its benefits type of cholesterol across racial lines.
Researchers at Oregon Health & Science University’s Knight Cardiovascular Institute analyzed 23,901 medical profiles from the Reasons for Geographic and Racial Differences in Stroke Study (REGARDS) and compared risk factors for cardiovascular events occurring in middle-aged black and white patients.
The study was funded by the National Institutes of Health (NIH), a medical research agency under the US Department of Health and Human Services, and was published in the Journal of the American College of Cardiology on Monday, November 21.
Of the thousands of REGARDS participants analyzed, the researchers narrowed their findings to patients who were enrolled in the study in 2003 and 2007, and then followed the patients’ medical records for 10 to 11 years.
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 a decade-long period, the researchers found that 664 black patients and 951 white patients experienced a heart attack or heart attack-related death.
“It is well accepted that low levels of HDL cholesterol are harmful, regardless of race. Our study tested these 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 marks HDL as beneficial cholesterol, and whether it holds true across ethnic groups,” added Pamir, associate professor of medicine at Oregon Health & Science University, Portland.
High-density lipoprotein is said to be beneficial because it has been shown to absorb cholesterol from the blood and transport it back to the liver, according to the US Centers for Disease Control and Prevention (CDC).
The liver is said to flush cholesterol out of the body, which can reduce a person’s chances of developing heart disease and stroke if there are high levels of HDL cholesterol.
Low-density lipoprotein (LDL), also known as “bad cholesterol,” makes up most of the cholesterol in the body, according to the CDC.
High levels of LDL cholesterol are associated with an increased risk of heart disease and stroke.
“When your body has too much LDL cholesterol, LDL cholesterol can build up on the walls of blood vessels,” the CDC wrote in an online explanation of cholesterol. “This accumulation is called a ‘plaque’.”
Analysis of REGARDS data in the new study confirmed that high levels of LDL cholesterol and triglycerides (neutral fats) result in a “moderately increased risk of cardiovascular disease,” according to the NIH.
Low levels of HDL cholesterol were found to increase the risk of cardiovascular disease in white patients, but the same was not true for black patients, according to the study.
At the same time, the study found that high levels of HDL cholesterol were not always associated with lower odds of cardiovascular events — regardless of race.
The authors of the study conclude that risk of cardiovascular diseases calculators using readings of HDL cholesterol levels could give inaccurate predictions for black patients.
“HDL cholesterol has long been an enigmatic risk factor for cardiovascular disease,” Sean Coady, deputy chief of the epidemiology branch of the National Heart, Lung, and Blood Institute’s Division of Cardiovascular Sciences, wrote in a statement.
“The findings suggest a deeper dive into epidemiology lipid metabolism is warranted,” Coady continued. “Especially in terms of how race can modify or mediate these relationships.”
fullMr the published study can be found on the Journal of the American College of Cardiology website at jacc.org.