Keeping Cholesterol
Under Control
Like the literary split personality, it has a good side because
it is needed for certain important body functions. But for many
Americans, cholesterol also has an evil side. When present in
excessive amounts, it can injure blood vessels and cause heart
attacks and stroke.
The body needs cholesterol for digesting dietary fats, making
hormones, building cell walls, and other important processes.
The bloodstream carries cholesterol in particles called lipoproteins
that are like blood-borne cargo trucks delivering cholesterol
to various body tissues to be used, stored or excreted. But
too much of this circulating cholesterol can injure arteries,
especially the coronary ones that supply the heart. This leads
to accumulation of cholesterol-laden "plaque" in vessel
linings, a condition called atherosclerosis.
When blood flow to the heart is impeded, the heart muscle becomes
starved for oxygen, causing chest pain (angina). If a blood
clot completely obstructs a coronary artery affected by atherosclerosis,
a heart attack (myocardial infarction) or death can occur.
The body needs cholesterol for digesting dietary fats, making
hormones, building cell walls, and other important processes.
The bloodstream carries cholesterol in particles called lipoproteins
that are like blood-borne cargo trucks delivering cholesterol
to various body tissues to be used, stored or excreted. But
too much of this circulating cholesterol can injure arteries,
especially the coronary ones that supply the heart. This leads
to accumulation of cholesterol-laden "plaque" in vessel
linings, a condition called atherosclerosis.
When blood flow to the heart is impeded, the heart muscle becomes
starved for oxygen, causing chest pain (angina). If a blood
clot completely obstructs a coronary artery affected by atherosclerosis,
a heart attack (myocardial infarction) or death can occur. (See
"How a Heart Attack Happens." <attack.html>)
Heart disease is the number one killer of both men and women
in this country. More than 90 million American adults, or about
50 percent, have elevated blood cholesterol levels, one of the
key risk factors for heart disease, according to the National
Heart, Lung, and Blood Institute's National Cholesterol Education
Program.
While the institute estimates that heart disease killed nearly
half a million in 1996, the most recent year for which figures
are available, a study published in the New England Journal
of Medicine in September 1998 says heart disease deaths have
declined steadily over the last 30 years. Indeed, between 1990
and 1994, heart disease deaths decreased by 10.3 percent, the
study says. From this and other studies, it appears that this
is due largely to improvements in medical care after heart attack,
a reduction in the number of repeat heart attacks, and better
prevention of heart disease development.
A key factor in this drop is that the public, patients and doctors
today are better informed about the risks associated with elevated
cholesterol and the benefits of lifestyle changes and medical
measures aimed at lowering blood cholesterol. "Public health
initiatives such as the National Cholesterol Education Program
have raised consumer awareness, promoted effective interventions,
and have likely contributed to the reduction in heart disease
deaths," says David Orloff, M.D., of the Food and Drug
Administration's division of metabolic and endocrine drug products.
Another factor in the drop may be a relatively new class of
drugs called statins. These have provided doctors with an arsenal
of therapies to lower elevated blood cholesterol levels, often
dramatically. To date, FDA has approved six statin drugs.
When Blood Cholesterol Becomes a Problem
Two types of lipoproteins and their quantity in the blood are
main factors in heart disease risk:
*Low-density lipoprotein (LDL)--This "bad" cholesterol
is the form in which cholesterol is carried into the blood and
is the main cause of harmful fatty buildup in arteries. The
higher the LDL cholesterol level in the blood, the greater the
heart disease risk.
*High-density lipoprotein (HDL)--This "good" cholesterol
carries blood cholesterol back to the liver, where it can be
eliminated. HDL helps prevent a cholesterol buildup in blood
vessels. Low HDL levels increase heart disease risk.
One of the primary ways LDL cholesterol levels can become too
high in blood is through eating too much of two nutrients: saturated
fat, which is found mostly in animal products, and cholesterol,
found only in animal products. Saturated fat raises LDL levels
more than anything else in the diet.
Several other factors also affect blood cholesterol levels:
*Heredity--High cholesterol often runs in families. Even though
specific genetic causes have been identified in only a minority
of cases, genes still play a role in influencing blood cholesterol
levels.
* Weight--Excess weight tends to increase blood cholesterol
levels. Losing weight may help lower levels.
* Exercise--Regular physical activity may not only lower LDL
cholesterol, but it may increase levels of desirable HDL.
* Age and gender--Before menopause, women tend to have total
cholesterol levels lower than men at the same age. Cholesterol
levels naturally rise as men and women age. Menopause is often
associated with increases in LDL cholesterol in women.
*Stress--Studies have not shown stress to be directly linked
to cholesterol levels. But experts say that because people sometimes
eat fatty foods to console themselves when under stress, this
can cause higher blood cholesterol.
Though high total and LDL cholesterol levels, along with low
HDL cholesterol, can increase heart disease risk, they are among
several other risk factors. These include cigarette smoking,
high blood pressure, diabetes, obesity, and physical inactivity.
If any of these is present in addition to high blood cholesterol,
the risk of heart disease is even greater.
The good news is that all these can be brought under control
either by changes in lifestyle--such as diet, losing weight,
or an exercise program--or quitting a tobacco habit. Drugs also
may be necessary in some people. Sometimes one change can help
bring several risk factors under control. For example, weight
loss can reduce blood cholesterol levels, help control diabetes,
and lower high blood pressure.
But some risk factors cannot be controlled. These include age
(45 years or older for men and 55 years or older for women)
and family history of early heart disease (father or brother
stricken before age 55; mother or sister stricken before age
65).
What Is High Blood Cholesterol?
Cholesterol levels are determined through chemical analysis
of a blood sample taken from a finger prick or from a vein in
the arm. Home cholesterol kits, first approved in 1993, test
only for total cholesterol levels but are as accurate as tests
done in a doctor's office, says Steven Gutman, M.D., director
of FDA's division of clinical laboratory devices. "These
tests can give a consumer very valuable information when screening
for high cholesterol," he says. "But they shouldn't
be considered substitutes for a test conducted in a doctor's
office." He adds that if test results are elevated, consumers
should see a doctor right away for a more refined blood analysis.
The National Cholesterol Education Program considers cholesterol
testing in a doctor's office to be the preferred way because
the patient can get advice immediately about the meaning of
the results and what to do.
Besides determining total cholesterol levels, doctors often
order a lipoprotein profile that shows the amounts of LDL, HDL,
and another type of blood fat called triglycerides. This information
gives doctors a better idea of heart disease risk and helps
guide any treatment.
Cholesterol levels are measured in milligrams per deciliter
(mg/dL). The National Cholesterol Education Program developed
the following classifications for people over age 20 who do
not have heart disease:
· Desirable blood cholesterol--Total blood cholesterol
is less than 200 mg/dL; LDL is lower than 130 mg/dL.
· Borderline high cholesterol--Total level is between
200 and 239 mg/dL or LDL is 130 to 159 mg/dL.
· High blood cholesterol--Total level is greater than
240 mg/dL or LDL is 160 mg/dL or higher. For patients with heart
disease, LDL above 100 mg/dL is too high. In addition, an HDL
level less than 35 mg/dL is considered low and increases the
risk of heart disease.
The main goal of cholesterol treatment is to lower LDL in people
without heart disease. If the LDL level is in the "high"
category and fewer than two other risk factors for heart disease
are present, the goal is an LDL level lower than 160 mg/dL.
If two or more risk factors are present, the goal is less than
130 mg/dL. If a patient already has heart disease, LDL levels
should be 100 mg/dL or less. By reducing LDL, heart disease
patients may prevent future heart attacks, prolong their lives,
and slow down or even reverse cholesterol buildup in the arteries,
according to the National Heart, Lung, and Blood Institute.
Home