Cholesterol
Cholesterol, a complex alcohol constituent of all animal fats and oils. It can be activated to form vitamin D. Cholesterol is one of a group of compounds known as sterols and is related to such other sterols as the sex hormones and the hormones of the adrenal cortex.
A close relationship exists among levels of blood cholesterol in the body, those of other fats or lipids, and the development of atherosclerosis (see Artery). In this disorder, plaques containing cholesterol are deposited on the walls of arteries, particularly those of small and medium size, reducing their inside diameter and the flow of blood. Clotting of blood, such as may occur in the coronary arteries to cause a heart attack, is most likely to develop at places where arterial walls are roughened by such plaques.
Although many foods, particularly dairy products and meat fat, contain cholesterol, the body also synthesizes this sterol from cholesterol-free substances. Nevertheless, investigation indicates that a cholesterol-rich diet causes abnormally high levels of cholesterol and the related fats and lipids in the blood. Evidence strongly indicates that people with such high levels are more likely to develop atherosclerosis and heart attacks than those with lower levels. Also significant is the fact that scientists have identified two forms of cholesterol-carrying proteins in the blood, called high-density and low-density lipoproteins. The low-density form is thought to promote atherosclerosis, whereas the high-density component may retard it.
A close relationship exists among levels of blood cholesterol in the body, those of other fats or lipids, and the development of atherosclerosis (see Artery). In this disorder, plaques containing cholesterol are deposited on the walls of arteries, particularly those of small and medium size, reducing their inside diameter and the flow of blood. Clotting of blood, such as may occur in the coronary arteries to cause a heart attack, is most likely to develop at places where arterial walls are roughened by such plaques.
Although many foods, particularly dairy products and meat fat, contain cholesterol, the body also synthesizes this sterol from cholesterol-free substances. Nevertheless, investigation indicates that a cholesterol-rich diet causes abnormally high levels of cholesterol and the related fats and lipids in the blood. Evidence strongly indicates that people with such high levels are more likely to develop atherosclerosis and heart attacks than those with lower levels. Also significant is the fact that scientists have identified two forms of cholesterol-carrying proteins in the blood, called high-density and low-density lipoproteins. The low-density form is thought to promote atherosclerosis, whereas the high-density component may retard it.
Persons who have abnormally high levels of cholesterol—especially low-density cholesterol—on a congenital basis can reduce their risk of heart attack by lowering their blood cholesterol. This is done by following a diet low in cholesterol and saturated fats, getting sufficient exercise, and using certain drugs. See Nutrition, Human.
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