What is high cholesterol?
High cholesterol is an excess of cholesterol in your blood. Cholesterol is a type of lipid, which is a group of fats and fatlike substances found in your body and in the foods you eat. A high cholesterol level is often due to a problem with your lipoproteins (low-density lipoproteins, or LDL, and high-density lipoproteins, or HDL), which are combinations of cholesterol, fat, and protein that your body uses to transport cholesterol and fat nutrients in your blood. The other important lipid nutrient that your body processes and distributes along with cholesterol is triglyceride, a fat nutrient that your muscle cells use for energy and that your body stores in your fat tissue for later use.
Why is high cholesterol a risk factor for coronary artery disease?
An imbalance of these cholesterol-carrying lipoproteins can lead to a buildup of cholesterol inside your arteries. Although doctors do not completely understand the process, this excess cholesterol gets deposited in the walls of your arteries, which contributes to the development of coronary artery disease. The hard plaque that forms in your arteries as a result of atherosclerosis is made largely of cholesterol.
A desirable cholesterol level also includes a balance of the different forms of cholesterol, which are listed below.
Low-density lipoprotein (LDL)
LDL carries cholesterol from the liver to other parts of the body where it is needed for cell repair and other activities. But under certain conditions, LDL cholesterol builds up in the walls of the arteries. For this reason, LDL cholesterol is often referred to as "bad" cholesterol. In general, cholesterol-lowering efforts are most often aimed at reducing levels of LDL cholesterol to reduce the risk of atherosclerosis, heart attack, and other complications.
High-density lipoprotein (HDL)
HDL cholesterol is often referred to as "good" cholesterol because it helps remove excess "bad" (LDL) cholesterol from the body. HDL cholesterol picks up leftover cholesterol from the bloodstream and carries it to the liver for disposal. Low HDL cholesterol increases the risk of coronary artery disease, and high levels of HDL cholesterol appear to help protect against heart disease. If you are at risk for heart disease, it may be beneficial to raise your HDL cholesterol levels.
An HDL level that is:
Triglycerides are another form of fat found in the blood. High triglyceride levels may contribute to fat buildup in the heart arteries and increase the risk of developing coronary artery disease (CAD).
The following are general triglyceride guideline levels. A triglyceride level of:
Lowering LDL and total cholesterol levels can help lower the risk of CAD, as well as heart attack, stroke, and death, in many people with average to high cholesterol levels. People at high risk for CAD are especially encouraged to keep their cholesterol levels low.
For more information, see the topic High Cholesterol.
- Grundy SM, et al. (2001). Executive summary of the third report of the National Cholesterol Education Program (NCEP) Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III). JAMA, 285(19): 2486–2497.
- Grundy SM, et al. (2004). Implications of recent clinical trials of the National Cholesterol Education Program Adult Treatment Panel III Guidelines. Circulation, 110(2): 227–239. [Erratum in Circulation, 110(6): 763.]
Last Revised: July 2, 2010
Author: Healthwise Staff
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