When Good Cholesterol Goes Bad


When good cholesterol goes bad, it goes really bad, according to a new report from Nature Medicine.  HDL, or high-density lipoprotein, can become very bad for you, particularly when it lines your arterial walls.

According to the new study, good cholesterol contains a protein called apolipoprotein A1, which gives HDL its ability to help protect the heart.  However, in the artery wall, if this protein appears in high quantities, apoliprotein A1 renders HDL’s protective properties useless.  In fact, what happens is apoA1 is oxidized by myeloperoxidase, which is what ultimately then renders HDL useless.

Dr. Stanley Hazen of the Cleveland Clinic and his team at the Preventive Cardiology & Rehabilitation in the Miller Family Heart and Vascular Institute decided to see if it was possible that HDL cholesterol was not as good as all the studies have previously indicated.  627 patients were involved in the study; all reported to a cardiology clinic and all presented with elevated levels of abnormal HDL cholesterol.  In fact, Dr. Hazen’s study indicated that apoA1 being oxidized by myeloperoxidase would stop HDL cholesterol’s cardio-protective properties and cause serious issues.

Oxidation is a normal part of the digestive process, and generally happens on the cellular level.  It’s the oxidation of apoA1 by myeloperoxidase that can cause significant issue as far as HDL cholesterol is concerned.  The focus is now on preventing good cholesterol from going bad in the first place.

This doesn’t mean that society’s approach to healthy eating should change when good cholesterol goes bad, according to Dr. Hazen.  The message that’s gone out to society for years is still important as far as diet is concerned.  Society still needs to focus on eating from all the food groups and getting an appropriate amount of exercise.  It’s still important to eat healthfully, but medical professionals are trying to determine the best possible route in preventing good cholesterol from becoming harmful.

Dr. Hazen’s team from the Cleveland Clinic found that once the HDL cholesterol had become abnormal through this oxidation process, it could flow throughout the arteries and other blood vessels, thereby blocking them and contributing to arterial disease.

While it became clear as a result of the study that those with this dysfunctional HDL cholesterol were automatically at greater risk for heart disease and the health issues associated with it, what remains unclear is what exactly causes the oxidation of the apoA1 to occur in the first place.  What’s apparent is that if HDL cholesterol is in high quantities in arterial walls, with the accompanying high amount of apoA1, it’s more than likely this protein will be oxidized by myeloperoxidase and therefore put patients at a higher risk for having heart conditions and heart disease in general.

When good cholesterol goes bad, it tends to get those learning about cholesterol concerned.  Dr. Hazen and his team of researchers, among others, are questioning why the dysfunction would occur with HDL cholesterol.  What is clear is that this abnormal HDL cholesterol can cause significant issues and that standard HDL cholesterol may contain greater problems than originally anticipated.

By Christina St-Jean


Nature Medicine

The Journal of Biological Chemistry

Daily Mail


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