Raising 'Good Cholesterol' Levels May Not Help Against Heart Attack
The so-called "good cholesterol" may not be so after all, according to a new study, published Wednesday in The Lancet. While previous studies have shown that higher levels of high-density lipoprotein (HDL) protects against heart attack, the latest study said this might not be the case.
Researchers used a new technique to test the heart attack risk for people a genetic predisposition to high HDL. People who had the genetic variant, approximately 2.6 percent of the population, had higher HDL levels but no less risk of heart attack.
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"The expectation was that the people who carried this genetic variant would have a lower heart attack risk, but that is not what we found," Dr. Sekar Kathiresan, study coauthor and researcher at Harvard Medical School, told WebMD.
The researchers said the findings put a nail in the coffin in the theory that high HDL levels protect against heart attack.
"After several blows to the head of this theory, it is on the ropes, or maybe even down for the count," Dr. Philip Greenland, study coauthor and senior associate dean for clinical and translational research at the Feinberg School of Medicine, told ABC News.
Dr. Christopher Cannon, a professor of medicine at Harvard Medical School, who was not involved in the study, told ABC News that while the study does put a damper on the theory, more research needs to be done in order to conclusively say HDL does not protect against heart attack.
"It casts some doubt on the benefits of higher HDL, but the real answers will come from clinical trials of new medications that raise HDL," he said. "We are testing a drug now... that increases HDL by 60 mg/dl on average -- and that will hopefully answer the question on whether HDL is important."
While there is definitely a correlation between high HDL levels and lower heart attack risk, scientists can not conclusively say the HDL levels are responsible for the lower risk, Dr. Robert Eckel, a professor of medicine at the University of Colorado School of Medicine, told WebMD.
"HDL levels are related to risk, but that doesn't mean that raising HDL is beneficial," he said. "What we do know is that lowering LDL has a big impact on risk, so the take-home message remains 'Get those LDL numbers down.'"
Dr. Michael Lauer, director of the division of cardiovascular sciences at the National Heart, Lung and Blood Institute, told the New York Times that researchers need to reevaluate just what high HDL levels indicate.
"The current study tells us that when it comes to HDL we should seriously consider going back to the drawing board, in this case meaning back to the laboratory," he said. ""We need to encourage basic laboratory scientists to figure out where HDL fits in the puzzle - just what exactly is it a marker for."
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