The effect of "good" cholesterol on cardiovascular disease may be more complicated than previously thought, according to a new
analysis.
Cholesterol has many important functions in the body. In the bloodstream, it's transported in several forms that include low-density lipoprotein (LDL) and high-density lipoprotein (HDL).
When there's too much cholesterol in your blood, the cholesterol from LDL can increase your risk for developing cardiovascular diseases such as heart attack and stroke.
Higher levels of HDL, in contrast, have been associated with a lower risk of cardiovascular disease. However, while treatment trials have shown that lowering LDL reduces the risk of heart disease, recent clinical trials haven't found that medicines aimed at raising HDL reduce the risk of heart
attack.
A team led by Dr. Sekar Kathiresan of Massachusetts General Hospital, Broad Institute and Harvard Medical School explored the relationship between HDL and heart
disease.
“Some ways of raising HDL cholesterol might not reduce risk of myocardial infarction in human beings.” Kathiresan says. “Therefore, if an intervention such as a drug raises HDL cholesterol, we cannot automatically assume that risk of myocardial infarction will be
reduced.”
Clinical trials are now underway to examine the cardiovascular benefits and risks of drug treatments that raise HDL levels. Future studies will be needed to understand both the role of HDL cholesterol and why its levels are associated with heart disease risk. It's possible that HDL itself may not directly lower the risk of heart disease but that blood HDL reflects another factor that
does.
The study was partly supported by NIH's National Heart, Lung and Blood Institute (NHLBI). Results appeared in the online early edition of the Lancet on May 17, 2012.
Source
http://www.nih.gov
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