Different types of cholesterol were previously thought to have either healthy or unhealthy effects.
Doctors have been telling their patients for years that high levels of high-density lipoprotein (HDL) — or “good cholesterol” — could help protect them from heart disease, but a new study is contradicting this long-held advice.
HDL was traditionally thought of as protective because of how it carries cholesterol to the liver, where it’s processed. But it turns out, HDL may not have as many health benefits as previously thought, according to a study published Monday in the Journal of the American College of Cardiology. While low levels of it were associated with an increased risk of heart disease in white adults, this wasn’t necessarily the case among Black adults, which took even the study’s own researchers by surprise.
“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 at the Oregon Health and Science University School of Medicine. “And I certainly did not expect low levels to have no predictive value for Black adults.”
Here are more details on the new study’s shocking findings and how it underscores the need for more diverse clinical trials.
What are the details of the cholesterol study?
Researchers looked at data over 10 years from nearly 24,000 adults across the U.S. (about 42 percent who took part were Black). Participants were all similar in age, cholesterol levels, and other heart disease risk factors.
The study was originally created to look at how cholesterol levels in middle-aged adults without heart disease affected their future risk, but researchers ended up finding out that the benefits of “good” cholesterol can vary by race. For instance, low levels of HDL cholesterol didn’t translate into a higher risk of heart disease in Black Americans like they did for white participants. Still, what held true for both groups is that high HDL levels that were previously thought to be protective — above 60 mg/dL — weren’t linked with lower coronary heart disease risks in either demographic.
Calls for additional research
Since the study was released, many doctors and health professionals have said that the study underscores the need for including more diverse populations in clinical trials, as similar studies have traditionally left out people of color.
“The biggest failure of medicine has been the lack of clinical trial diversity,” cardiologist Dr. Jayne Morgan told Healthline.
Inclusion is especially important when it comes to looking at risk factors of heart disease — Black Americans between the ages of 18 to 49 are twice as likely to die from heart disease than their white counterparts, according to the Centers for Disease Control.
Cardiologist Dr. Yu-Ming Ni told Healthline that the outcome of the study suggests that underlying health conditions could be at play, such as high blood pressure, diabetes, and obesity. Additionally, lack of access to quality care can also account for worse health outcomes in Black Americans than other adults.
The bottom line
High HDL levels won’t necessarily safeguard your heart health — instead, they can add to the total cholesterol number, and more studies are showing levels above 80 can be detrimental when it comes to your health.
“Literally, on a daily basis someone comes to my office with an HDL of 80 or 90,” Dr. Howard Weintraub told TODAY. “When I tell them that doesn’t mean they are bulletproof, they are crestfallen because their doctor told them not to worry about their bad cholesterol because the good cholesterol was so good.”
For context, cholesterol levels are typically measured in milligrams per deciliter of blood, and according to the American Heart Association, the optimal total cholesterol level for an adult is about 150 mg/dL, with low-density lipoprotein or “bad” cholesterol levels either at or below 100 mg/dL. So it’s not a bad idea to watch your cholesterol as a whole and eat heart-healthy foods, like leafy green vegetables and whole grains.
