“Good” and “Bad” Cholesterol: These well-known figures have long been the protagonists of heart health saga. But in a major plot twist, it turns out that “good” cholesterol isn’t always so good.
Over the past dozen years, studies of particles that carry so-called good cholesterol (called high-density lipoprotein, or HDL) have come up with a more nuanced and conflicting story about HDL’s impact on cardiovascular disease.
A large new study raises new questions.high level HDL cholesterol not linked to heart disease prevention Among black or white participants, the researchers reported in November Journal of the American College of Cardiology. There was a split for low levels of HDL cholesterol, which was associated with a higher risk of heart disease in white participants but not in black participants.
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The study is the first to identify differences in risk associated with low levels of HDL cholesterol between blacks and whites. It also adds to growing evidence that high levels of HDL cholesterol are not necessarily helpful for a person’s heart health.
HDL seems to have other nice features. But the researchers also found that HDL’s role in health is complex and ever-changing, with much to unravel.
Link between HDL and heart disease unclear
Cholesterol has long been interpreted as “good” and “bad.” High levels of the “good” type were associated with lower risk of cardiovascular disease, while high amounts of the “bad” type (carried by low-density lipoprotein, or LDL particles) were associated with higher risk.
One of the major reports labeling HDL cholesterol “good” came from the Framingham Heart Study, a government-led study launched in 1948 to investigate risk factors for cardiovascular disease. In 1977, researchers at Framingham reported a HDL cholesterol inversely associated with coronary heart disease risk In a group consisting of white participants.
But later studies have weakened the premise that high levels of AUT are beneficial for heart health.some people Gene Mutation That Raises HDL Cholesterol Levelsfor example, the risk of heart attack is no lower than that of people without the mutation (Serial Number: 5/18/12). A class of drugs used to increase HDL cholesterol does a good job of boosting the numbers, but No effect on cardiovascular risk.
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A person’s HDL cholesterol level is only part of the story, though. Usually reported in blood tests, this level reflects the amount of cholesterol contained in HDL particles. HDL carries cholesterol from the arteries to the liver and out of the body. This helps prevent cholesterol from building up on artery walls, which can eventually impede blood flow.
More recently, research on HDL has begun to look beyond its cholesterol payload. “The big realization over the last decade or so is that while you can measure cholesterol, it doesn’t really reflect what HDL actually does in the body,” says Anand Rohatgi, a cardiologist at the University of Texas Southwestern Medical Center in Dallas.
The cholesterol-removing effect of HDL appears to be important. One measure of performance in this work is HDL’s ability to take up cholesterol from a type of cell called a macrophage. In a study of nearly 3,000 adults, 49 percent of whom were black, The higher this ability, the lower the risk of heart disease seizure or stroke, Rohatgi and colleagues in New England Journal of Medicine Year 2014.
Clearing cholesterol from the body is just one of the many jobs of HDL.HDL and Anti-inflammatory and other protective effects Appears to protect against cardiovascular disease. But even these effects don’t always result in net benefits.In some cases HDL can become so dysfunctional that it Reduced ability to accept cholesterol, which causes inflammation. The fact that HDL’s role can change depending on the environment makes studying HDL particles challenging, Rohatgi said.
The performance of HDL is far from being tested as part of a routine physical exam. Nathalie Pamir, a researcher studying cardiology at Oregon Health & Science University in Portland, said it’s unclear “how to do this for the public.”
Heart-health effects of HDL cholesterol may vary by race
As researchers work to gain a more complete understanding of HDL and how it can be better used as a clinical marker, the idea that HDL cholesterol is uniformly “good” persists. A person’s HDL cholesterol level remains an entry in widely used calculators for estimating cardiovascular risk. Pamir and her colleagues wanted to study what high and low HDL cholesterol levels mean in contemporary diverse populations.
In the new study, the team analyzed data from the REGARDS trial, which was designed to examine underlying regional and racial differences in stroke deaths in the United States. The study included nearly 24,000 participants — 42 percent of whom were black — who did not initially have coronary heart disease. Over about 10 years, 664 of 10,095 black participants and 951 of 13,806 white participants had a heart attack or died of heart disease.
The team found that, consistent with past research, elevated levels of “bad” LDL cholesterol were associated with an increased risk of coronary heart disease. But for HDL cholesterol, high levels were not protective for anyone, and low levels only predicted higher risk in white people. The findings suggest that it may be necessary to re-examine how HDL cholesterol is used in cardiovascular disease risk calculators, Pamir said.
HDL cholesterol is not only beneficial, but “complicated,” she said. If a patient has high HDL cholesterol, the doctor “could say, ‘Well, we don’t know what that means at the moment.'”
Although this study suggests that the effect of HDL cholesterol levels on disease risk may vary by race, it is important to remember that race is a social construct, not a biological construct, said Clyde Clyde, chief of cardiology at Northwestern University Feinberg School of Medicine. Yancy said in Chicago.
Some risk factors for coronary heart disease, including high blood pressure and smoking, “were more prevalent among self-identified African-Americans,” he said.there’s still one Community access to health care, nutritious food and educational opportunities and employment can influence these risk factors (Serial Number: 5/15/17). “There is something unique about places and local histories that can contribute to the burden of high blood pressure, obesity and even diabetes,” Yancy said.
More research is needed to understand the reasons behind the underlying racial differences reported in the study, and what it means for HDL cholesterol levels and cardiovascular disease risk, Yancy said. But high levels of LDL cholesterol — which can build up on artery walls — are still associated with an increased risk, he said. “LDL cholesterol seems to be the most relevant barometer we have.”
Researchers still don’t understand the full picture of all the factors known to affect cardiovascular disease risk. The number of heart attacks seen by cardiologists in patients with normal cholesterol levels and blood pressure suggests that with current methods, “we’re not capturing the full risk,” Yancy said.