Some shine may have worn off “good” cholesterol’s halo. A new genetics study shows that merely raising levels of high-density lipoprotein — also known as HDL or good cholesterol — does not help protect against heart attacks.
The finding appears to contrast sharply with population studies showing that people with high levels of HDL have a lower than average risk of heart attack. But the results, published online May 17 in the Lancet, may mean that blood levels of good cholesterol serve as indicators of some other biological process that protects the heart, and that HDL itself is not directly involved in heart health.
Doctors often use measurements of two types of cholesterol in the blood as a tool for identifying patients facing a higher risk of heart attack. Data collected from large studies show a consistent pattern: People with high levels of low-density lipoprotein, called LDL or bad cholesterol, stand a greater than average chance of having a heart attack. Those epidemiological data have been backed up by drug studies showing that lowering LDL levels also lowers heart attack risk.
But the case for HDL has been less clear. “As a predictor, HDL is perfect. It’s unequivocal,” says Benjamin Voight, a geneticist at the University of Pennsylvania in Philadelphia and a lead author of the new study. Yet drugs that raise HDL levels haven’t performed well in clinical trials. On May 7, the drug company Roche announced that a trial of its HDL-boosting drug dalcetrapib had been stopped because the drug was not effective.