A fat-like substance that is an important constituent of body cells and is also involved in the formation of hormones and bile salts. Cholesterol in the blood is made by the liver from foods, especially saturated fats, although a small amount is absorbed directly from cholesterol-rich foods such as eggs. High blood cholesterol levels increase the risk of atherosclerosis, and with it the risk of coronary artery disease or stroke. In general, cholesterol transported in the blood in the form of low-density lipoproteins (LDLs) or very low-density lipoproteins (VLDLs) is a risk factor for these conditions, while cholesterol in the form of high-density lipoproteins (HDLs) seems to protect against arterial disease. Blood cholesterol levels are influenced by diet, heredity, and metabolic diseases such as diabetes mellitus, and can be measured by blood tests. Levels below 5.2 mmol/L are acceptable; higher levels may require further tests. Dietary changes can lower cholesterol slightly; drugs such as simvastatin achieve a greater reduction.


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