Saturday, July 28, 2012


Cholesterol is a dreaded word for many people because of its perceived association with atherosclerosis and heart attack.  Some people are aware of the differentiation between High Density Lipoproteins (HDL) and Low Density Lipoproteins (LDL). Lay man recognizes HDL as good cholesterol and LDL as its bad cousin, with the latter causing heart disease. Even many physicians advise their clients to work for increasing the HDL level as high as possible imagining that it can protect the heart. There are millions of dollars of investment riding on the above hypothesis to develop drugs that can boost HDL levels in the blood though no appreciable success has yet been achieved. Against such a background comes an earth shaking finding that a high HDL level need not be a guarantee against heart disease and those with high HDL inherited genetically cannot be considered as less prone to heart attack. Here is a take on this new revelation which seems to have turned the clock back regarding the current knowledge about the role of lipo proteins on human health.   

"Now, a new study that makes use of powerful databases of genetic information has found that raising HDL levels may not make any difference to heart disease risk. People who inherit genes that give them naturally higher HDL levels throughout life have no less heart disease than those who inherit genes that give them slightly lower levels. If HDL were protective, those with genes causing higher levels should have had less heart disease. Researchers not associated with the study, published online Wednesday in The Lancet, found the results compelling and disturbing. Companies are actively developing and testing drugs that raise HDL, although three recent studies of such treatments have failed. And patients with low HDL levels are often told to try to raise them by exercising or dieting or even by taking niacin, which raised HDL but failed to lower heart disease risk in a recent clinical trial. "I'd say the HDL hypothesis is on the ropes right now," said Dr. James A. de Lemos, a professor at the University of Texas Southwestern Medical Center, who was not involved in the study. Dr. Michael Lauer, director of the division of cardiovascular sciences at the National Heart, Lung and Blood Institute, agreed. "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," said Dr. Lauer, who also was not connected to the research. "We need to encourage basic laboratory scientists to figure out where HDL fits in the puzzle — just what exactly is it a marker for." But Dr. Steven Nissen, chairman of cardiovascular medicine at the Cleveland Clinic, who is helping conduct studies of HDL-raising drugs, said he remained hopeful. HDL is complex, he said, and it is possible that some types of HDL molecules might in fact protect against heart disease".

The million dollar question is whether high HDL level in blood is maintained due to good health or lower level of HDL heralds changes that lead to heart associated problems. It looks like HDL may not be a sure marker any more for insurance against heart disease while LDL certainly is a marker for bad health. Probably the present approach to cholesterol management will undergo dramatic changes if the above findings are confirmed by future studies. One question that naturally arises out of this development is whether the multi billion dollar Statin drug industry is going to be adversely affected. According to the authors of the above study, it is always healthy if LDL levels are controlled and those who cannot reduce the same will have to resort to drug intervention using Statins.


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