Higher HDL doesn't protect against heart attacks
Many people tell me that they are concerned about their lower HDL levels when they lower total cholesterol. The body makes HDL according to the total serum cholsterol level present; when cholesterol drops, less HDL is needed.
Nevertheless, many people have been told that they need to raise HDL levels to avoid cardiac events.
The following is adapted from a Bloomberg News Service report on a new medical study and should help allay these unfounded concerns about raising HDL levels. (A link to the Journal article is at the end)
Researchers are raising doubts about a theory drugmakers have spent more than $1 billion pursuing after a study showed so-called good cholesterol didn't reduce the risk of heart attacks.
People with a genetic condition that causes them to produce very low levels of HDL cholesterol were no more likely to have a heart attack than those with normal levels, according to a study in the June 8, 2008 issue Journal of the American Medical Association [JAMA. 2008;299(21):2524-2532]. Previous studies predicted that HDL cholesterol helped ferry artery-clogged plaque from the body, leading researchers to expect these patients with low levels of the beneficial cholesterol to have twice the risk of a heart attack.
Pfizer Inc., Merck Co. and Roche Holdings AG have spent years developing drugs that increase production of HDL cholesterol. The new research throws that strategy into question and shows HDL plays no role in preventing heart attacks, said Anne Tybjaerg-Hansen, a study author and clinical biochemistry researcher at Copenhagen University Hospital.
"There is really no evidence that this method is going to work," said Tybjaerg-Hansen. "This theory has been around for a long time, but this [new] study just doesn't support it."
The reason may be that other HDL cholesterol research examined patients with high levels of triglycerides, the chemical form of fat. Triglycerides, not patients' low HDL levels, may have caused their increased heart risk, Tybjaerg-Hansen said.
This may explain why the drug torcetrapib, which Pfizer spent more than $1 billion developing, raised HDL levels without providing heart benefits, the study said. Analysts had expected torcetrapib would have more than $14 billion in in annual sales. Pfizer dropped it in 2006 because it increased deaths.
To see an abstract of the JAMA article referred to above is available, click here or go to