The study casts doubt on the role of HDL “good” cholesterol in heart health

Experts said the findings call for a reevaluation of how HDL is used to predict the risk of developing heart disease. Photo by Steve Collender/Shutterstock

Blood levels of HDL, the so-called “good” kind of cholesterol, may not matter much for heart health after all — especially for black people, a major new study suggests.

The study of nearly 24,000 US adults found that low HDL levels were associated with a slightly higher risk of heart attack among white people. However, this was not the case for black adults.

Meanwhile, high levels of HDL — traditionally lauded as heart-healthy — had no effect on heart risks for black or white adults.

Experts said the findings call for a reevaluation of how HDL is used to predict the risk of developing heart disease. More broadly, they said, researchers need to understand whether different “traditional” risk factors for heart disease have similar effects for all people.

“We need to expand our understanding of risk factors for all racial and ethnic groups,” said senior researcher Natalie Pamir, an associate professor of medicine at Oregon Health & Science University in Portland.

That understanding, she added, translates into treatment guidelines. “And our guidelines should work for everyone,” Pamir said.

HDL, or high-density lipoprotein, first earned its reputation as “good” cholesterol with the Framingham Heart Study. As early as the 1970s, a link was found between higher HDL levels and a lower risk of heart attack.

The Framingham Study is a major, still ongoing research project: Decades ago, it identified many of the factors now considered key to whether people will develop heart problems or have a stroke: high blood pressure, high levels of “bad” LDL cholesterol, smoking, and obesity increase these risks, while exercise and higher HDL decrease the odds.

Today, HDL is considered too low if it is below 40 mg/dL for men or 50 mg/dL for women. Values ​​between these numbers and 59 mg/dL are considered normal, but people are encouraged to aim for the “desired” 60 or higher.

The problem is that all the Framingham participants were white. And some recent studies with more racial diversity question whether low HDL is “bad” for everyone’s heart.

The new findings, Pamir said, show that for black Americans, that idea doesn’t hold up.

The study, published Monday in the Journal of the American College of Cardiology, included 23,901 US adults age 45 and older who did not have coronary heart disease at baseline. This refers to heart disease caused by a build-up of “plaques” clogging the arteries.

About 42% of participants were black and 58% were white.

Over the next decade, just over 1,600 people suffered a heart attack or died from coronary heart disease. It found that low HDL predicted a moderately higher risk of heart problems, but only in white people: those with low levels had a 22% higher risk than white participants with normal HDL.

Among black adults, low HDL was unrelated to heart disease risk. Moreover, high HDL offers no protection to anyone.

The high HDL findings aren’t surprising, Pamir noted: Trials testing HDL-raising drugs also found no heart protection.

“But the dogma is still ‘high HDL is good,'” Pamir said. “You still get a pat on the back if your HDL is high.”

But the consequences, she added, could be greater than an undeserved pat on the back. Doctors use HDL, along with other risk factors such as high blood pressure and high LDL, to assess patients’ risk of developing heart disease in the next 10 years. And it guides treatment decisions, such as whether to prescribe a statin.

For black patients, however, neither low nor high HDL is a useful measurement.

If the findings lead to changes in how HDL is used, that would be a good thing, said Dr. Keith Ferdinand, a cardiologist and professor at Tulane University School of Medicine in New Orleans.

For black patients, risk factors such as high blood pressure, obesity and elevated LDL should be given more weight, according to Ferdinand, who wrote an editorial published alongside the study.

But ultimately, he said, social inequalities are the main reason black Americans are about a third more likely to die of heart disease or stroke than white Americans.

“It’s not enough to just set up HDL,” emphasized Ferdinand. “We need to address our structural inequalities.”

He said that when people can’t afford healthy food, don’t have safe places to exercise, face chronic stress and can’t pay for medicine, they are at greater risk of developing heart disease — and they are harder to deal with when they do.

As for low HDL, Pamir said the steps recommended to raise it are good: They include exercise, quitting smoking and avoiding “trans” fats in processed foods.

So black adults with low HDL should continue to do these things, Pamir said. However, they should not stress about increasing their numbers.

The study was funded by the US National Institutes of Health.

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