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Raising HDL Cholesterol May Not Be The Answer

Is There A Bad Side To “Good” (HDL) Cholesterol?

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Updated October 08, 2008

Updated October 08, 2008
Although lowering cholesterol is important - especially bad cholesterol - raising HDL cholesterol is equally important. However there is new evidence that indicates that this could increase your risk of heart disease.

High density lipoproteins (HDL) are considered to be the "good" cholesterol in the body. Having a high level of HDL cholesterol has a protective effect on the heart, since it prevents cholesterol from accumulating in the blood and on blood vessels.

Researchers, however, are now finding out that HDL may have a bad side to it. HDL is composed of two parts: protein and fat. Scientists have discovered that the protein part on some of the HDL molecules may change over time, and may actually have the ability to promote heart disease.

On August 22, 2007, scientists reported these new findings about the structure of HDL at an American Chemical Society conference. They compared HDL cholesterol in both healthy individuals and individuals with heart disease and found that different proteins were present in the HDL cholesterol of individuals with heart disease. In particular, the scientists found that a protein called ApoE was present in high amounts in those individuals with heart disease. Scientists are still trying to understand what causes the HDL proteins to convert to the type that can be detrimental to the heart.

This sheds some light on why drugs specifically designed to raise HDL levels have never made it past clinical trials and onto pharmacy shelves. For instance, torcetrapib appeared to be a promising new drug that would raise HDL levels. It did raise HDL levels, but clinical trials had to be stopped abruptly due to the fact that some individuals taking torcetrapib developed high blood pressure and heart failure. Additionally, scientists noted that although HDL levels were high in patients taking torcetrapib, it did not prevent atherosclerosis from forming on vessel walls. In other words, this drug may have raised levels of HDL containing the wrong kinds of proteins.

Although more research is needed, these findings may change the way new drugs are developed and offer an explanation as to why some individuals may get heart disease, despite having the “perfect” lipid profile (low LDL levels, high HDL levels).

Sources:

American Chemical Society press release. Auagust 22, 2007. Available at: http://www.eurekalert.org/pub_releases/2007-08/acs-wbt081007.php. Accessed 29 August 2007.

Nissen SE, Tardiff JC, Nicholls SJ et al. Effect of torcetrapib on the progression of coronary atherosclerosis. N Engl J Med 2007; 356: 1304-16.

Royal Society of Chemistry. August 23, 2007. Available at: http://www.rsc.org/chemistryworld/News/2007/August/23080701.asp. Accessed August 30, 2007.

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