Both heredity and diet have a significant influence on a patient’s LDL, HDL and total cholesterol levels. For example, familial hypercholesterolemia (FH) is a common inherited disorder whose victims have a diminished number or nonexistent LDL receptors on the surface of liver cells.

The resultant decreased activity of the LDL receptors limits the liver’s ability to remove LDL cholesterol from blood. Thus, affected family members have abnormally high LDL cholesterol levels in the blood. They also tend to develop atherosclerosis and heart attacks during early adulthood.

Diets that are high in saturated fats and cholesterol decrease the LDL receptor activity in the liver, thereby raising the levels of LDL cholesterol in the blood. Fats are classified as saturated or unsaturated according to their chemical structure. Saturated fats are derived primarily from meat and dairy products and can raise blood cholesterol levels. Some vegetable oils made from coconut, palm, and cocoa are also high in saturated fats. On the other hand, most other vegetable oils are high in unsaturated fats. Unlike saturated fats, unsaturated fats do not raise blood cholesterol and can sometimes lower cholesterol. Olive and canola oil are high in monounsaturated fats, which may have a protective effect against coronary heart disease. Unfortunately, some vegetable oils are converted to saturated fats during a process called “hydrogenation” which can be required for food processing.

Does lowering LDL cholesterol prevent atherosclerosis and heart attacks?

In the past 10 years, clinical trials have conclusively demonstrated that lowering LDL cholesterol reduces heart attacks and saves lives. The benefits of lowering LDL cholesterol include:

 
• Reducing the formation of new cholesterol plaques;  
• Eliminating existing plaques;  
• Preventing rupture of existing plaques;  
• Decreasing the risk of heart attacks; and  
• Lowering the chance of strokes.

How low should LDL cholesterol be?

The National Cholesterol Education Program (NCEP) has issued LDL cholesterol treatment guidelines for adults. The NCEP target levels are different for people who have varying risks for heart attacks. For example, since individuals who have already suffered a heart attack have a greater chance of experiencing another heart attack than individuals without known coronary heart disease, their LDL cholesterol levels need to be more aggressively lowered than people without known coronary heart diseases.

In July 2004 the NCEP (National Cholesterol Education Program) issued a new set of guidelines for treatment of high blood cholesterol in adults. Please read the New Cholesterol Guidelines article for more information.

Whether the NCEP LDL cholesterol treatment target levels are low enough is controversial. An increasing number of experts in treating blood lipid disorders believe that aggressively lowering LDL cholesterol below 80 further decreases atherosclerosis and heart attack rates. In order to achieve these levels, diet and exercise are insufficient and moderate to high doses of a statin drug also will be necessary on a long-term basis. However, the safety of moderate to high doses of statins over several decades is unknown. Thus, the decision to aggressively reduce the patient’s LDL cholesterol level below the levels recommended by NCEP should be individualized after consultation with a doctor familiar with the treatment of lipid disorders. Factors that must be taken into account in making treatment decisions include the patient’s age, family history of early coronary heart diseases, other risk factors, and cholesterol profile.

How can LDL cholesterol levels be lowered?

In order to lower LDL cholesterol, the activity level of the LDL receptors must be increased. LDL receptor activities can be increased by diets that are low in cholesterol and saturated fats and by medications.

Lowering LDL cholesterol involves losing excess weight, exercising regularly, and following a diet that is low in saturated fat and cholesterol. Medications are prescribed when diet and exercise cannot reduce the LDL cholesterol to acceptable levels. The most effective and widely used medications to lower LDL cholesterol are called statins. Other medications used in lowering LDL cholesterol and in altering cholesterol profiles include Nicotinic Acid (niacin), fibrates such as gemfibrozil (Lopid), and resins such as cholestyramine (Questran).

Is lowering LDL cholesterol enough?

Unfortunately, the prevention and treatment of atherosclerosis are more complicated than just lowering LDL cholesterol levels. LDL cholesterol reduction is only half of the battle against atherosclerosis. Individuals who have normal or only mildly elevated LDL cholesterol levels can still develop atherosclerosis and heart attacks even in the absence of other risk factors such as cigarette smoking, high blood pressure, and diabetes mellitus. Additionally, successfully lowering elevated LDL cholesterol levels cannot always prevent atherosclerosis and heart attacks. In many clinical trials to lower LDL cholesterol, there were patients who adhered to their assigned diets, faithfully took their cholesterol-lowering medications, successfully lowered their LDL cholesterol to target levels, yet still suffered progressive atherosclerosis and heart attacks. It is clear that while lowering LDL cholesterol below NCEP target levels is an important step, there are other factors involved.

What are the other risk factors for heart attacks?

The other risk factors include:

 
• Abnormally low HDL cholesterol levels.  
• The size of the LDL cholesterol particles in the blood may be too small. Scientists have found that the size of LDL cholesterol particles in the blood is predominantly genetically inherited. People who have small and dense LDL cholesterol particles have a higher risk of developing atherosclerosis and heart attacks than those who have larger and more buoyant particles.  
• Elevated Lp(a) cholesterol levels. The level of Lp(a) cholesterol is also predominantly genetically inherited. Individuals with elevated levels of Lp(a) cholesterol have a higher rate of atherosclerosis and risk of heart attacks.  
• Elevated homocysteine levels.