Cholesterol is a fatty chemical which is an important part of the outer lining (membrane) of cells in the body. Cholesterol is found mainly in foods that come from animals. LDL lipoprotein is the major carrier of cholesterol in the blood. LDL cholesterol is called "bad" cholesterol, because elevated LDL cholesterol is associated with an increased risk of coronary heart disease. LDL lipoprotein deposits cholesterol on the artery walls, causing the formation of a hard, thick substance called cholesterol plaque. Over time, cholesterol plaque causes thickening of the artery walls and narrowing of the arteries, a process called atherosclerosis.
Atherosclerotic disease of coronary arteries is called coronary heart disease. Coronary heart disease is the most common cause of death in the United States, accounting for about 600,000 deaths annually. Atherosclerosis can also lead to brain damage from stroke. In addition to smoking and blood pressure, blood cholesterol is a major controllable risk factor for coronary heart disease.
Your blood cholesterol level is affected not only by what you eat but also by how quickly your body makes LDL ("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-cholesterol level is high or low. The following factors are the most important:
Heredity. Your genes influence how high your LDL ("bad") cholesterol 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-cholesterol level.
What you eat. Two main nutrients in the foods you eat make your LDL ("bad") cholesterol 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-cholesterol 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. For more, please visit the Nutrition Center.
Weight. Excess weight tends to increase your LDL ("bad") cholesterol level. If you are overweight and have a high LDL-cholesterol level, losing weight may help you lower it. Weight loss also helps to lower triglycerides and raise HDL ("good") cholesterol levels. For more, please visit the Weight Loss Center.
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 to 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 ("good") cholesterol but does not lower LDL ("bad") cholesterol. 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. For more, please visit our Stress Center.
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Some of the above information has been provided with the kind permission of the National Institutes of Health (www.nih.gov)