A study supported by the National Institutes of Health finds that high-density lipoprotein (HDL) cholesterol, often called the “good cholesterol,” may not be as effective as scientists once thought at uniformly predicting the risk of cardiovascular disease among adults of different backgrounds. different race and ethnicity.
Research published in Journal of the American College of Cardiology, found that while lower levels of HDL cholesterol predicted an increased risk of heart attack or related death for white adults — a long accepted association — this was not the case for black adults. In addition, higher HDL cholesterol levels were not associated with a lower risk of cardiovascular disease for either group.
“The goal was to understand this well-established link describing HDL as the beneficial cholesterol, and if this applies across all races,” said Natalie Pamir, PhD, lead author of the study and assistant professor of medicine at the institute. Knight Heart and Vascular Institute at Oregon Health & Science University, Portland. “It has been accepted that low levels of HDL cholesterol are harmful, regardless of race. Our research tested these assumptions.”
To do this, Pamir and her colleagues reviewed data on 23,901 adults from the United States who participated in the Reasons for Geographic and Racial Differences in Stroke Study (REGARDS). The previous studies that shaped perceptions of “good” cholesterol levels and heart health were conducted in the 1970s through research with the majority of white adults in the study. For the current study, the researchers were able to look at how cholesterol levels in middle-aged black and white adults without heart disease who lived across the country interfered with future cardiovascular events.
Study participants were enrolled in REGARDS between 2003-2007 and researchers analyzed information collected over a period of 10 to 11 years. Black and white study participants shared similar characteristics, such as age, cholesterol levels, and underlying risk factors for heart disease, including having diabetes, high blood pressure, or smoking. During this time, 664 black adults and 951 white adults experienced a heart attack or heart attack-related death. Adults with higher levels of LDL cholesterol and triglycerides had a modest increase in the risk of cardiovascular disease, which is consistent with previous research findings.
However, the study was the first to find that lower HDL cholesterol levels only predicted an increased risk of cardiovascular disease for white adults. It also expands on findings from other studies showing that higher levels of HDL cholesterol are not always associated with lower cardiovascular events. The REGARDS analysis was the largest US study to show this was true for both black and white adults, suggesting that higher amounts of “good” cholesterol may not provide cardiovascular benefits for either group.
“What I hope this type of research will demonstrate is the need to revisit the risk prediction algorithm for cardiovascular disease,” Pamir said. “It could mean that in the future we won’t be tabbed by our doctors for having high levels of HDL cholesterol.”
Pamir explained that as researchers study the role of HDL cholesterol in supporting heart health, they are exploring different theories. One is quality over quantity. That is, rather than getting more HDL, the quality of HDL’s job — in capturing and transporting excess cholesterol from the body — may be more important for supporting cardiovascular health.
They also take a microscopic look at the properties of HDL cholesterol, including analysis of hundreds of cholesterol transport-related proteins and how different ligands, based on a single protein or groups of proteins, can improve predictions of cardiovascular health.
“HDL cholesterol has long been a puzzling risk factor for cardiovascular disease,” explained Sean Cody, vice chair of the Epidemiology Branch in the Division of Cardiovascular Sciences at the National Heart, Lung, and Blood Institute (NHLBI). A fat diet is justified, particularly in terms of how race modifies or mediates these relationships.”
The authors conclude that, in addition to supporting ongoing and future research with diverse populations to explore these links, the findings suggest that cardiovascular risk calculators using HDL cholesterol may lead to inaccurate predictions for black adults.
“When it comes to risk factors for heart disease, they cannot be narrowed down to one race or ethnicity,” Pamir said. “It should apply to everyone.”
The REGARDS study was funded by the National Institute of Neurological Disorders and Stroke and the National Institute on Aging and received additional support from the NHLBI.