A study financed by the National Institutes of Health discovered that high-density lipoprotein (HDL) cholesterol, commonly referred to as “good cholesterol,” may not be as helpful as previously assumed in predicting cardiovascular disease risk among adults of diverse races and ethnicities.
The research, which was published in the Journal of the American College of Cardiology(link is external), discovered that while low levels of HDL cholesterol predicted an increased risk of heart attacks or related deaths for white adults – a long-accepted association – this was not the case for Black adults. Furthermore, higher HDL cholesterol levels were not related with a lower risk of cardiovascular disease in either group.
Nathalie Pamir, Ph.D., a senior author of the study and associate professor of medicine at the Knight Cardiovascular Institute at Oregon Health & Science University in Portland, stated, “The objective was to determine if this long-established link that identifies HDL as the beneficial cholesterol holds true for all ethnicities.” “It is widely acknowledged that low levels of HDL cholesterol are harmful, regardless of race. Our investigation examined these hypotheses.”
Pamir and her colleagues analyzed data from 23,901 adults in the United States who participated in the Reasons for Geographic and Racial Differences in Stroke Study(external link) (REGARDS). Previous studies that influenced beliefs of “excellent” cholesterol levels and heart health were conducted with a majority of white adult volunteers in the 1970s. For this study, researchers were able to examine the correlation between the cholesterol levels of Black and white, middle-aged adults without heart disease from across the country and future cardiovascular events.
Between 2003 and 2007, study participants joined in REGARDS, and researchers reviewed data collected over a 10- to 11-year period. Participants of both races shared similar features, including age, cholesterol levels, and underlying risk factors for heart disease, such as diabetes, hypertension, and smoking. During this time period, 664 Black adults and 951 white people had a heart attack or died from a heart attack. Consistent with prior study, adults with elevated levels of LDL cholesterol and triglycerides had marginally increased risks for cardiovascular disease.
However, this was the first study to indicate that lower HDL cholesterol levels predicted an increased risk of cardiovascular disease only among white adults. It also expands on previous research indicating that elevated HDL cholesterol levels are not necessarily related to a decreased risk of cardiovascular events. The REGARDS analysis was the largest U.S. study to demonstrate that this was true for both Black and white adults, suggesting that higher than ideal levels of “good” cholesterol may not offer cardiovascular benefits for either group.
“I hope this type of research establishes the necessity to reassess the cardiovascular disease risk prediction system,” Pamir added. It could mean that in the future, our doctors will no longer congratulate us for having greater HDL cholesterol levels.
Pamir noted that researchers are examining several hypotheses as they investigate the impact of HDL cholesterol in promoting heart health. One is that quality trumps quantity. In other words, the quality of HDL’s activity in taking up and moving excess cholesterol from the body may be more significant for promoting cardiovascular health than the quantity of HDL.
In addition, they are examining the properties of HDL cholesterol at a microscopic level, including the analysis of hundreds of proteins associated with transporting cholesterol and how varying associations based on a single protein or groups of proteins may improve cardiovascular health predictions.
“HDL cholesterol has long been a puzzling risk factor for cardiovascular disease,” noted Sean Coady, deputy branch chief of epidemiology in the Division of Cardiovascular Sciences at the National Heart, Lung, and Blood Institute (NHLBI). “The findings suggest that further investigation into the epidemiology of lipid metabolism is necessary, particularly in terms of how race may affect or mediate these associations.”
In addition to supporting ongoing and future research with varied populations to study these relationships, the authors conclude that cardiovascular disease risk calculators that use HDL cholesterol may produce erroneous projections for Black adults.
“Risk factors for heart disease cannot be restricted to a single race or ethnicity,” stated Pamir. “They must be applicable to everyone.” The REGARDS study is supported by the National Institute of Neurological Disorders and Stroke, the National Institute on Aging, and the NHLBI.