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Cholesterol: Genetics and Risk Factors

Cholesterol is a wax-like substance needed for cell membranes and some hormones. High levels of cholesterol are linked to coronary artery disease and heart attacks (myocardial infarction).

Cholesterol is carried through the blood on lipoproteins.  The two most common lipoproteins are high-density (HDL) and low-density (LDL).  HDL is “good” cholesterol because it is believed to carry cholesterol away from arteries and back to the liver and remove excess cholesterol.  A high HDL level seems to protect against heart disease.  LDL is “bad” cholesterol because if there is too much of it, it can build up and form plaques in the arteries.  A high LDL level increases your risk for heart disease.

We get cholesterol through 1) diet and 2) our bodies.  Animal products contain cholesterol (eggs, meat, shellfish, dairy products).  You should limit your dietary cholesterol intake, as your body makes all the cholesterol it needs.  However, it is important to note that even if you do not consume dietary cholesterol, you may be getting cholesterol in another way:  saturated fatty acids and trans fatty acids are converted to cholesterol.  If you are trying to reduce cholesterol levels, limit both your dietary cholesterol from animal products and saturated and trans fats.

Coronary artery disease (CAD) is the leading cause of death for men and women in the United States.  CAD is caused by the buildup of plaques (cholesterol and triglycerides) in the arteries that supply the heart.  This blockage slows blood flow, which reduces the amount of oxygen and nutrients into the heart muscle.  This causes chest pain (angina) and if left untreated a heart attack (myocardial infarction).

Risk Factors

Age, sex, hereditary, and race are non-modifiable risk factors that affect a person’s cholesterol level, which in turn affects CAD risk.  Smoking, diet, stress level, and lack of physical activity are modifiable risk factors.

The National Institute of Health names both age and a family history of heart disease as risk factors, but says “It doesn’t mean that you will develop CAD if you have one or both.”  The NIH recommends lifestyle changes and/or medications to lessen genetic influences.

The Mayo Clinic names “Family history” of heart disease as a risk factor for CAD.  It says “Your risk [of CAD] is highest if your father or a brother was diagnosed with heart disease before age 55, or your mother or sister developed it before age 65.”

In addition to family history and age, race and gender are risk factors for CAD.  African Americans have an increased risk for heart disease because they have a higher rate of hypertension than Caucasians.  Additionally, men are more likely than women to have heart disease, and at a younger age.

Genetics

The MEF2A gene is the first gene found to be a direct cause for coronary artery disease.  A deletion of the 21-base pairs of this gene result in a change in heart protein functions, resulting in coronary artery disease and heart attack.  This gene is a “trigger” for heart disease, although it is not found in all people who have CAD or a heart attack.  It is believed to be a rare mutation in the general population, although the fact that such a genetic mutation triggers heart disease is significant.

According to the American Heart Association, heart and coronary artery disease can be inherited. For this reason, if your parents had heart or blood vessel disease, you are likely to develop the disease. “A number of genes have been reported to be associated with heart disease, stroke, and high blood pressure in large population-based studies.” However, much more research needs to be done before the impact of a single gene on an individual person is understood.

Our bodies are a result of the interplay between environmental and genetic factors.  Science is only beginning to undercover the secrets behind common diseases and conditions.  While we may not know or understand the genetic cards we are dealt, we can employ proven behaviors to promote a healthy lifestyle.

Lowering Cholesterol

  • Limit alcohol
  • Stop smoking
  • Exercise regularly
  • Avoid foods containing high levels of cholesterol
  • Curb foods with high saturated and unsaturated fatty acids