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Cholesterol and Coronary Heart Disease
Heart disease is caused by narrowing of the coronary arteries that feed the heart. Like any muscle, the heart needs a constant supply of oxygen and nutrients, which are carried to it by the blood in the coronary arteries. When the coronary arteries become narrowed or clogged by cholesterol and fat deposits—a process called atherosclerosis—and cannot supply enough blood to the heart, the result is coronary heart disease (CHD). If not enough oxygen-carrying blood reaches the heart, you may experience chest pain called angina. If the blood supply to a portion of the heart is completely cut off by total blockage of a coronary artery, the result is a heart attack. This usually is due to a sudden closure from a blood clot forming on top of a previous narrowing.
Cholesterol’s Role in CHD
Cholesterol is a waxy, fat-like substance that occurs naturally in all parts of the body and that your body needs to function normally. It is present in cell walls or membranes everywhere in the body, including the brain, nerves, muscle, skin, liver, intestines, and heart. Your body uses cholesterol to produce many hormones, vitamin D, and the bile acids that help to digest fat. It takes only a small amount of cholesterol in the blood to meet these needs. If you have too much cholesterol in your bloodstream, the excess is deposited in arteries, including the coronary arteries, where it contributes to the narrowing and blockages that cause the signs and symptoms of heart disease.
Your blood cholesterol level is affected not only by what you eat but also by how quickly your body makes LDL-cholesterol (LDL-C), often called the "bad" cholesterol, and disposes of it. In fact, your body makes all the cholesterol it needs, and it is not necessary to take in any additional cholesterol from the foods you eat.
Many factors help determine whether your LDL-C level is high or low. The following factors are the most important:
Heredity. Your genes influence how high your LDL-C is by affecting how fast LDL is made and removed from the blood. One specific form of inherited high cholesterol that affects 1 in 500 people is familial hypercholesterolemia, which often leads to early heart disease. But even if you do not have a specific genetic form of high cholesterol, genes play a role in influencing your LDL-C level.
What you eat. Two main nutrients in the foods you eat make your LDL-C level go up: saturated fat, a type of fat found mostly in foods that come from animals; and cholesterol, which comes only from animal products. Saturated fat raises your LDL-C level more than anything else in the diet. Eating too much saturated fat and cholesterol is the main reason for high levels of cholesterol and a high rate of heart attacks in the United States. Reducing the amount of saturated fat and cholesterol you eat is a very important step in reducing your blood cholesterol levels.
Weight. Excess weight tends to increase your LDL-C level. If you are overweight and have a high LDL-C level, losing weight may help you lower it. Weight loss also helps to lower triglycerides and raise HDL-cholesterol (HDL-C) levels.
Physical activity/exercise. Regular physical activity may lower LDL-C and raise HDL-C levels.
Age and sex. Before the age of menopause, women usually have total cholesterol levels that are lower than those of men the same age. As women and men get older, their blood cholesterol levels rise until about 60-65 years of age. After the age of about 50, women often have higher total cholesterol levels than men of the same age.
Alcohol. Alcohol intake increases HDL-C but does not lower LDL-C. Doctors don’t know for certain whether alcohol also reduces the risk of heart disease. Drinking too much alcohol can damage the liver and heart muscle, lead to high blood pressure, and raise triglycerides. Because of the risks, alcoholic beverages should not be used as a way to prevent heart disease.
Stress. Stress over the long term has been shown in several studies to raise blood cholesterol levels. One way that stress may do this is by affecting your habits. For example, when some people are under stress, they console themselves by eating fatty foods. The saturated fat and cholesterol in these foods contribute to higher levels of blood cholesterol.
National Cholesterol Education Program Guidelines
Total cholesterol less than 200 mg/dL and HDL-C 40 mg/dL or higher
Unless you have other risk factors for heart disease, your chance of a heart attack is relatively low.
Total cholesterol less than 200 mg/dL and HDL-C less than 40 mg/dL
Total cholesterol 200-239 mg/dL, HDL-C 40 mg/dL or higher, and fewer than 2 risk factors
Total cholesterol 200-239 mg/dL, HDL-C less than 40 mg/dL or 2 or more risk factors
Total cholesterol 240 mg/dL and above