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Cholesterol 
Cholesterol is sort of a "cousin" of fat. Both fat and
cholesterol belong to a larger family of chemical compounds called
lipids. All the cholesterol the body needs is made by the liver. It
is used to build cell membranes and brain and nerve tissues.
Cholesterol also helps the body produce steroid hormones needed for
body regulation, including processing food, and bile acids needed
for digestion.
People don't need to consume dietary cholesterol because the
body can make enough cholesterol for its needs. But the typical
U.S. diet contains substantial amounts of cholesterol, found in
foods such as egg yolks, liver, meat, some shellfish, and whole-
milk dairy products. Only foods of animal origin contain
cholesterol.
Cholesterol is transported in the bloodstream in large
molecules of fat and protein called lipoproteins. Cholesterol
carried in low-density lipoproteins is called LDL-cholesterol; most
cholesterol is of this type. Cholesterol carried in high-density
lipoproteins is called HDL-cholesterol. (See "Fat Words.")
A person's cholesterol "number" refers to the total amount of
cholesterol in the blood. Cholesterol is measured in milligrams per
deciliter (mg/dl) of blood. (A deciliter is a tenth of a liter.)
Doctors recommend that total blood cholesterol be kept below 200
mg/dl. The average level in adults in this country is 205 to 215
mg/dl. Studies in the United States and other countries have
consistently shown that total cholesterol levels above 200 to 220
mg/dl are linked with an increased risk of coronary heart disease.
(See "Lowering Cholesterol" in the March 1994 FDA Consumer.)
LDL-cholesterol and HDL-cholesterol act differently in the
body. A high level of LDL-cholesterol in the blood increases the
risk of fatty deposits forming in the arteries, which in turn
increases the risk of a heart attack. Thus, LDL-cholesterol has
been dubbed "bad" cholesterol.
On the other hand, an elevated level of HDL-cholesterol seems
to have a protective effect against heart disease. For this reason,
HDL-cholesterol is often called "good" cholesterol.
In 1992, a panel of medical experts convened by the National
Institutes of Health (NIH) recommended that individuals should have
their level of HDL-cholesterol checked along with their total
cholesterol.
According to the National Heart, Lung, and Blood Institute
(NHLBI), a component of NIH, a healthy person who is not at high
risk for heart disease and whose total cholesterol level is in the
normal range (around 200 mg/dl) should have an HDL-cholesterol
level of more than 35 mg/dl. NHLBI also says that an LDL-
cholesterol level of less than 130 mg/dl is "desirable" to minimize
the risk of heart disease.
Some very recent studies have suggested that LDL-cholesterol
is more likely to cause fatty deposits in the arteries if it has
been through a chemical change known as oxidation. However, these
findings are not accepted by all scientists.
The NIH panel also advised that individuals with high total
cholesterol or other risk factors for coronary heart disease should
have their triglyceride levels checked along with their HDL-
cholesterol levels.
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