It is well known that one of the most important ways to prevent and treat heart disease is lowering elevated levels of low-density lipoprotein (LDL). It is considered "bad" because excess amounts can accumulate in artery walls and cause plaque buildup. If the buildup blocks blood flow to the heart or brain, it can trigger a heart attack or stroke.
On the other hand, high-density lipoprotein (HDL) is commonly referred to as "good" cholesterol, but that may be misleading, according to an article on Harvard Health.
While HDL plays a role in heart health, its overall contribution is overrated, and in some cases, it can do more harm than good, the article says.
While the HDL level helps assess the risk of whether you are likely to develop cardiovascular disease, research has shifted the thinking about its role.
Your HDL level has little, if any, influence on the therapies prescribed to decrease heart disease and stroke risk.
"There is still so much we don't know or understand about HDL. But the evidence is clear that managing LDL levels is what matters most," said Jorge Plutzky, director of preventive cardiology at Harvard-affiliated Brigham and Women's Hospital.
Why it's not always 'good'
Some HDL particles gather excess cholesterol from the bloodstream and artery walls and deliver it to the liver, where it's broken down into harmless particles. In this way, HDL is considered "good".
But the HDL story is not that simple. HDL is not a single particle, but a family of different particles that come in various shapes and sizes. They can be small, medium, or large. Some types are spherical, while others are donut-shaped. This variety means not all HDL acts the same way. Some particles are great at grabbing excess cholesterol, while others are not. Some even transfer cholesterol the wrong way — away from the liver and into the blood-stream.
Increasing HDL does not improve outcomes. Genetics plays the major role in determining a person's HDL cholesterol level. Men who inherit genes that lead to a level less than 40 milligrams per deciliter (mg/dL) are at increased risk of developing cardiovascular disease. Many experts suggest that HDL levels between 40 mg/dL and 80 mg/dL are a sweet spot for men.
Whereas lowering LDL can significantly reduce the risk of heart attack, stroke and other cardiovascular problems, raising HDL levels does not have the same positive effects.
For instance, the results of studies involving a type of medicine that can raise HDL levels, called cholesteryl ester transfer protein (CETP) inhibitors, have been disappointing. Although these drugs can increase HDL levels by as much as 60% in some cases, higher levels did not lead to a lower risk for heart attacks, strokes, or clogged arteries. This is cited as a major reason why the FDA has not approved any of these drugs.
In addition, a 2022 study in JAMA Cardiology found that among people with coronary artery disease, those with very high HDL levels (80 mg/dL or higher) were about as likely to die from heart disease as people with very low HDL (30 mg/dL or lower).
"HDL levels often go up a little when people eat a healthy plant-based diet and exercise regularly," said Plutzky. "But following a healthy lifestyle also lowers LDL levels and thus lowers your risk for heart attack and stroke. It's these behaviors, not the slightly higher HDL levels that may result from them that are the driving factors."
So, while doctors may still refer to HDL as "good" cholesterol, given the evolving nature of our understanding of HDL, it is safest to focus on the bad stuff.
"No matter what your HDL level is, all your cardiovascular risk factors will determine your LDL goal level," Plutzky said. "Managing LDL levels is the top priority."
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