Cholesterol is a waxy substance your body needs to synthesize vitamin D from sunlight, produce hormones that regulate sexual function and other processes, manufacture bile acids that digest the fats in your diet and build healthy cells. While cholesterol is essential for these and other body functions, too much cholesterol puts you at risk for coronary heart disease, heart attack and stroke.
Components
Your liver and other cells in your body manufacture about 75 percent of your total cholesterol, while the remaining 25 percent comes from meat, dairy foods and other animal products in your diet. Cholesterol's waxy consistency prevents it from dissolving in your blood, so it travels around on carriers called lipoproteins. High-density lipoprotein, or HDL, is known as the "good" cholesterol and low-density lipoprotein, or LDL, is the "bad" cholesterol. Very-low-density lipoprotein, or VLDL, is produced in the liver and converted to LDL in your bloodstream. HDL makes up about 20 to 30 percent of your total cholesterol, LDL comprises 60 to 70 percent and VLDL accounts for 10 to 15 percent of your total cholesterol.
Goals
In 2001, an expert panel convened by the National Heart, Lung and Blood Institute established desirable goals for various types of cholesterol and stratified values outside the desirable range. You should aim for a desirable total cholesterol of less than 200 mg/dL. A total of 200 to 239 mg/dL is borderline high, and readings of 240 mg/dL and above are considered high. An LDL cholesterol reading below 100 mg/dL is optimal, readings from 100 to 129 mg/dL are near/above optimal, and those between 130 and 159 mg/dL are borderline high. An LDL level between 160 and 189 mg/dL is labeled as high and a value of 190 mg/dL or greater is described as very high. Since HDL is the beneficial form of cholesterol, shoot for readings of 60 mg/dL or greater, and realize that values of 40 mg/dL or less significantly increase your risk for coronary heart disease.
Effects
When you have too much LDL cholesterol in your blood, the excess lipoprotein combines with fats and other substances in the blood to form rigid plaques inside the walls of your arteries. Over time, these plaques restrict the flow of blood to your heart, brain and other vital organs. You may develop coronary heart disease and experience a heart attack or stroke. HDL cholesterol, on the other hand, carries excess LDL to your liver so it can be broken down and excreted from your body. HDL may also pull LDL from arterial plaques, improving blood flow to your tissues, says the American Heart Association.
Considerations
Your total cholesterol level will fluctuate from day to day as your diet and physical activity varies. If you have a single lab test showing an elevated total cholesterol level, your physician may advise you to improve your diet and exercise regimens but wait to repeat the test before starting any medical treatment. Your cholesterol values will be abnormally low if you are acutely ill, stressed, or recovering from surgery or a heart attack. Pregnancy causes a rise in cholesterol, so women should wait at least six weeks before going for a cholesterol test. Drugs such as steroid drugs, beta blockers for high blood pressure, birth control pills and vitamin D also increase cholesterol levels.
References
- American Heart Association: About Cholesterol
- Harvard Medical School Family Health Guide: Making Sense of Cholesterol Tests
- National Heart, Lung and Blood Institute: Detection, Evaluation and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III) Executive Summary
- Lab Tests Online: Cholesterol
