Jessica Wong, age 14, of Keen, N.H., for her question:
HOW DO WE GET CHOLESTEROL?
Cholesterol is a fatty substance found in all animal tissues. The human body manufactures most of its own cholesterol, but some enters the body in food. Butter, eggs, fatty meats and the meat of such organs as the brain and liver contain much cholesterol.
Cholesterol is a complex alcohol constituent. The body uses it to make bile acids, which aid digestion. The body also uses it to make some hormones, which are chemicals that influence various body activities.
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.
Sometimes fatty deposits containing cholesterol may collect on the inner wails of arteries, resulting in a hardening of the arteries. This condition is called arteriosclerosis.
The fatty deposits narrow the blood vessels and may deprive organs of food and oxygen. Blood clots can easily block such narrow vessels. A clot that blocks an artery of the heart causes a heart attack.
Some scientists believe that a diet too high in fats causes arterioscierosi s. Others feel that a defect in body chemistry causes the accumulation of fatty deposits.
Some scientists believe that a diet high in fats and cholesterol may be among the factors that cause cancer of the colon. Many doctors recommend diets low in fats for patients with too much cholesterol in their blood and some even prescribe drugs to decrease the body's production of cholesterol.
The brain, nerves and spinal cord have the highest concentration of cholesterol in the body.
Cholesterol and its derivatives are secreted through the oil glands of the skin to act as a lubricant and protective covering for the hair and skin.
Cholesterol sometimes forms crystals in the gallbladder that results in gallstones.
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.
In 1984, the United States National Heart, Lung and Blood Institute reported results of a study indicating that high levels of low density lipoproteins also increase the risk of heart attacks and heart disease.
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 can be done most of the time by following a diet low in cholesterol and saturated fats and by using certain drugs prescribed by the doctors.
The measure of cholesterol levels in the blood is given by medical people in the number of milligrams (mg.) of cholesterol per 100 milliliters (ml.) of blood serum. A normal level is from about 150 to 260 mg./100 ml.