Good cholesterol efficiency more important than quantity: Study

By Dr. Ananya Mandal, MDJan 13 2011

According to a new study the amount of good cholesterol a person has is not as important as how well that good cholesterol works to stop heart disease. Good cholesterol or High-Density Lipoprotein—also known as HDL is known to be healthy for the heart with people having high blood levels of HDL being at a lower risk of developing heart disease than people with low levels.

The new study published January 13 in the New England Journal of Medicine shows that it is not the numbers but the efficiency of the HDL molecule at removing fats from arteries that is a better predictor of who will develop heart disease.

Jay Heinecke, an endocrinologist at the University of Washington in Seattle, who wrote an editorial comment on the research in the same issue of the journal says that the results, “suggest that just measuring HDL levels isn’t enough to figure out what’s going on… It opens up the idea that there’s a lot we don’t know about HDL.”

The study led by Daniel Rader at the University of Pennsylvania School of Medicine in Philadelphia showed that some people had more efficient HDL than others. Healthy people with this trait, known technically as a higher cholesterol efflux capacity, had less thickening of their carotid arteries than did people with less efficient cholesterol-clearing HDL.

The team involved three groups: one group of people without heart trouble and two groups of surgical patients - those who had heart disease and those who did not. The team gauged the cholesterol-removing effectiveness of each person’s HDL. They also measured the patients’ HDL levels and the thickness of the walls of the carotid arteries in their necks. Thick artery walls are known to mean a higher risk for heart disease. They found that people whose HDL was most effective at removing bad cholesterol had thinner artery walls. HDL’s effectiveness was a better predictor of heart disease than how much HDL was in the body.

Rader added however, “We don’t yet have an assay or a test that can be used in a clinical setting,” but the study has shed light on the science of the matter.

Christopher Cannon, a cardiologist at Brigham and Women’s Hospital in Boston said, “It says that the good cholesterol is more complicated than the bad cholesterol story.” While bad cholesterol in a well explained manner clogged up arteries, “good cholesterol actually has to do something to pull bad cholesterol out of the arteries.” Exactly how the molecule accomplishes that task efficiently remains to be seen, and would be examined by Rader and his colleagues.

Dr. Robert Eckel, former president of the American Heart Association said, “I see plenty of people who have heart disease but who also have high levels of HDL. So what is going on there? Why aren’t they protected? This study may suggest their HDL isn’t working properly to carry out its function.”