28 October 2012

Canadian Scientists Discover Cause For High Levels of Bad Cholesterol (LDL)

Scientists have discovered the cause of high cholesterol in the body. With this discovery, it could lead to better prevention and treatment of cardiovascular disease.


Cholesterol is classified as a waxy steroid of fat. It is needed to build and maintain cell membranes, regulate what enters and exits the cell (membrane permeability) and modulate the "thickness" or viscosity of the cell (membrane fluidity).

Although cholesterol fulfill an important role in human health, high levels of cholesterol is harmful. A high cholesterol count may lead to stroke and heart disease. Cholesterol is also associated with atherosclerosis, a condition where the arteries start to harden making blood to flow through the heart and body difficult.

All cells need fats and cholesterol to build membranes that control its water content and water-soluble elements and to organize their internal structure and protein enzymatic systems.

Lipoproteins and LDL

Lipoproteins are responsible for allowing fat to move through the water inside and outside cells. There are five major group of lipoproteins:
  • Chylomicrons
  • Very-low-density lipoprotein (VLDL)
  • Intermediate-density lipoprotein (IDL)
  • Low-density lipoprotein (LDL)
  • High-density lipoprotein (HDL)
They all allow the transport of fat, including cholesterol, within the water around cells and within the water-based bloodstream.

Video: Understanding Cholesterol

Of the five groups, it is Low-density lipoprotein (LDL) that is identified as the bad type of cholesterol. LDL can transport cholesterol into the arterial wall. This may lead to the formation of plaque in the artery walls. When plaque starts to accumulate, the artery starts to narrow and harden and this leads to atherosclerosis.

Resistin Linked To LDL

Canadian scientists have discovered that a protein secreted by fat tissues called resistin increases the production of LDL in human liver cells.

The research, presented today at the Canadian Cardiovascular Congress shows that resistin accelerates the accumulation of LDL in arteries, increasing the risk of heart disease. It also shows that resistin adversely impacts the effects of cholesterol reducing drugs called statins. According to the study, 40 per cent of people who take statins are resistant to their impact on lowering blood LDL.

Dr. Shirya Rashid is the senior author of the study and assistant professor in the department of medicine at McMaster University. She notes that high blood resistin levels may be the cause of the inability of statins to lower patients' LDL cholesterol.

This may lead to new treatments that target and inhibit resistin which would allow statins to do their work.

"The possibilities for improved therapy for the causes of cardiovascular disease are very important," says Heart and Stroke Foundation spokesperson Dr. Beth Abramson. "About 40 per cent of Canadians have high blood cholesterol levels: it's a significant health concern in Canada."

Dr. Abramson notes that the research reconfirms the importance of maintaining a healthy weight and cholesterol level, two critical factors in the prevention of heart disease.


Heart and Stroke Foundation of Canada
Canadian Cardiovascular Congress
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