Cause of High LDL Cholesterol Discovered
A new discovery concerning bad cholesterol (low-density lipoprotein, LDL) could lead to important changes in how doctors treat this significant risk of heart disease and stroke. Scientists have found a protein that causes high LDL cholesterol, and this protein wears many hats in the bad cholesterol scene.
LDL cholesterol discovery is big news
LDL cholesterol is the neighborhood bully: it hangs out in the walls of blood vessels, eventually mixes with cells and debris, forms plaque, and blocks the free flow of blood. The more LDL in the blood vessels, the greater the risk of heart attack or stroke.
Now researchers at McMaster University have announced the discovery that resistin (also known as adipose tissue-specific secretory factor) , a protein secreted by fat tissue, causes high levels of LDL cholesterol in several ways.
- LDL is made in the liver, and resistin increases production of bad cholesterol by liver cells
- Resistin degrades LDL receptors in the liver, which boosts cholesterol levels because the body has difficulty eliminating it
- Resistin speeds up the accumulation of LDL in the blood vessels
- Resistin reduces the effects of statins, which are the most commonly prescribed drugs to treat high cholesterol
This last point is especially significant, according to the study's senior author, Dr. Shirya Rashid, assistant professor in the department of medicine at McMaster. She pointed out that "high blood resistin levels may be the cause of the inability of statins to lower patients' LDL cholesterol," a phenomenon that affects 40 percent of individuals who take the drugs.
What is high LDL cholesterol?
When you have your cholesterol levels checked, you and your doctor should keep the following guidelines in mind.
- Optimal LDL level: less than 100 mg/dL (milligrams per deciliter). Anyone who is at high risk of heart disease or who had heart disease should keep their LDL at an optimal level. People with diabetes and coronary artery disease together should strive for an LDL of less than 70 mg/dL
- Near optimal: 100 to 129 mg/dL
- Borderline high: 130 to 159 mg/dL. People who have a moderate to high risk of heart disease should keep their LDL less than 130 mg/dL
- High: 160 to 189 mg/dL
- Very high: 190 mg/dL or greater
Ways to lower your LDL cholesterol include eating a diet low in saturated fat (less than 7% of calories per day) and low in cholesterol (less than 200 mg daily), increasing the amount of fiber in your diet, and participating in regular aerobic exercise. Drug options include statins, fibrates, ezetimibe (Zetia®), and bile acid sequestrants, such as cholestyramine. Natural options can include niacin and red yeast rice.
Why this discovery is important
Now that scientists have identified a cause of LDL production and a reason why statins may not be effective in some patients, they can take a new path in developing therapies that focus on resistin. The discovery of a cause of high LDL cholesterol is important, but individuals still have a responsibility to maintain a healthy weight, follow a low-fat, low-cholesterol diet, exercise regularly, and not smoke to reduce their risk of heart disease and stroke.
Canadian Cardiovascular Congress