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Blood tests are a standard way of measuring cholesterol levels in the blood. Victor Torres/Stocksy United
  • Researchers say levels of high-density lipoprotein (HDL), commonly known as “good cholesterol,” can help predict heart disease risk in white adults.
  • However, they say HDL levels are not necessarily an accurate indicator of heart disease risk in Black adults.
  • They say the disparity emphasizes the need for different approaches to heart health for different ethnicities as well as more diverse participation in clinical trials.

New research supported by the National Institutes of Health (NIH) says high-density lipoprotein (HDL) – frequently called “good” cholesterol – may not be as good at predicting cardiovascular disease among adults of different ethnicities as once thought.

The study was published today in the Journal of the American College of Cardiology.

In it, researchers report that while low levels of HDL still predicted an increased risk of heart attacks or related deaths for white adults, the same wasn’t true for Black adults.

They also found higher HDL cholesterol levels weren’t associated with reduced cardiovascular disease risk for either group.

“The goal was to understand this long-established link that labels HDL as the beneficial cholesterol, and if that’s true for all ethnicities,” said Nathalie Pamir, Ph.D., the study’s senior author and an associate professor of medicine at the Knight Cardiovascular Institute at Oregon Health & Science University in Portland, in a statement.

“It’s been well accepted that low HDL cholesterol levels are detrimental, regardless of race. Our research tested those assumptions,” she added.

Pamir’s team looked at data from 23,901 adults in the United States over a 10-year to-11-year period who enrolled in the Reasons for Geographic and Racial Differences in Stroke Study (REGARDS) between 2003 and 2007.

Previous studies influencing accepted ideas about “good” cholesterol levels and heart health were done in the 1970s and 1980s, mostly using white adults.

The latest study involved researchers reviewing how cholesterol levels from both Black and white middle-aged adults without heart disease overlapped with cardiovascular events.

Participants shared similar characteristics of age, cholesterol levels, and underlying risk factors for heart disease such as diabetes, high blood pressure, or smoking. During this period, 664 Black adults and 951 white adults experienced a heart attack or heart attack-related death.

Adults with increased levels of low-density lipoprotein (LDL), so-called “bad” cholesterol, and triglycerides in their diets had modestly increased risks for cardiovascular disease, aligning with findings from previous studies.

However, the study was the first to determine lower HDL cholesterol levels only predicted increased cardiovascular disease risk for white adults. It also expands on findings from other studies showing high HDL cholesterol levels are not always associated with reduced cardiovascular events.

“What I hope this type of research establishes is the need to revisit the risk-predicting algorithm for cardiovascular disease,” Pamir said. “It could mean that in the future we don’t get a pat on the back by our doctors for having higher HDL cholesterol levels.”

Dr. Yu-Ming Ni, a cardiologist at MemorialCare Heart and Vascular Institute at Orange Coast Medical Center in California, told Healthline HDL is the “good” cholesterol because HDL particles pick up cholesterol around the body and bring it back to the liver to be processed.

“Think of HDL particles as the clean-up crew, whose job is to clean up after the LDL particles, referred to as the ‘bad’ cholesterol,” Ni said. “There seems to be a sweet spot for HDL cholesterol that reduces the risk of bad heart events.”

“Too little, and there isn’t enough clean-up going on. Too much might mean the cleaning crew is overwhelmed and unable to do their job of preventing heart disease,” Ni noted.

Ni told Healthline the study suggests that, compared to white Americans, African Americans don’t have a clear “sweet spot” for HDL cholesterol.

“Given that African Americans have generally worse cardiovascular outcomes than white Americans, this suggests that other factors may have a greater influence on cardiovascular health, particularly in the presence of other medical conditions such as high blood pressure, diabetes, and obesity,” Ni said.

“This study is useful for understanding population-based management of cardiovascular risk, but clinically, I suspect it will not influence the way I care for patients of African American descent,” Ni added. “HDL is but one of multiple risk factors for cardiovascular disease and treating the whole picture is often more beneficial.”

Dr. Jayne Morgan, a cardiologist and the clinical director of the COVID Task Force at Piedmont Hospital/Healthcare in Atlanta, told Healthline the study shows some bigger-picture insight.

“It is of paramount importance to have inclusion in clinical trials of everyone,” Morgan said. “This includes all demographics, races, and gender. Without it, there will never be health equity in medicine. The biggest failure of medicine has been the lack of clinical trial diversity.”

Morgan said the Food and Drug Administration (FDA) approves drugs and therapeutics without parallels in the demographic representation in the United States.

She compared it to the Tuskegee Experiment, a government-funded experiment observing the effects of syphilis on Black men without telling them about their condition or treating it.

“Blacks and other minorities are prescribed drugs that have scant information on them, but are FDA approved, nevertheless,” Morgan noted. “So often only real-world experience informs on safety and efficacy for minority populations.”

Pamir said researchers are exploring different theories about HDL cholesterol’s role in supporting heart health.

One aspect looks at quality over quantity, meaning that instead of having more HDL, the quality of HDL’s function – in picking up and transporting excess cholesterol from the body – may be more important for supporting cardiovascular health.

She said they’re also analyzing hundreds of proteins associated with transporting cholesterol and how varying associations, based on one protein or groups of proteins, may improve cardiovascular health predictions.

The authors also said their findings suggest cardiovascular disease risk calculators using HDL cholesterol could lead to inaccurate predictions for Black adults.

“When it comes to risk factors for heart disease, they cannot be limited to one race or ethnicity,” said Pamir. “They need to apply to everyone.”

Veronica Rouse, a registered dietitian who specializes in cardiac nutrition, told Healthline the study doesn’t change dietary guidelines for a healthy heart.

“It is still encouraged to lower your LDL cholesterol levels through food, as LDL cholesterol responds to nutrition therapy and is still shown to lower your risk of heart disease,” she said.

“One can reduce LDL cholesterol by reducing saturated fat intake, found mainly in fatty meats, lard, shortening, whole dairy products, sweet treats like cookies and cakes, and eliminating trans fats,” Rouse added.

Rouse said people should eat heart-healthy foods such as plant protein (soy products, nuts, seeds, beans, and legumes), soluble fiber (avocado, oats, barley, and other whole grains), and healthy fats (extra virgin olive oil, fatty fish and nuts, and seeds).