Cholesterol: the good and the bad
I'm confused about cholesterol. Is there good and bad cholesterol? If so, how do I get the appropriate amount of the good cholesterol, and what can I do to decrease the bad?
It's no wonder you're confused about cholesterol -- this natural fatty substance has gotten somewhat of a "bad rap." The truth is that cholesterol plays an important and needed role in body metabolism, and there are good and bad types. Your body needs cholesterol to function normally, especially in creating certain hormones, Vitamin D, and bile acids, which are important in the absorption of fat. Cholesterol is found in a wide range of foods, from eggs and red meat to shellfish.
A high blood cholesterol level indicates that you have more cholesterol in your bloodstream than your body needs. The higher your blood cholesterol level, the greater your risk for developing coronary artery disease, or atherosclerosis ("hardening of the arteries") -- the most common form of heart disease.
When there is too much cholesterol in your blood, the excess can become trapped on the walls of your arteries, causing atherosclerosis, and restricting the blood flow to the heart, says Gary L. Balady, M.D., director of preventive cardiology at Boston Medical Center and professor of medicine at Boston University School of Medicine. Anyone can develop high blood cholesterol, regardless of age, race, gender, or ethnic background. In fact, 52 million Americans now have a blood cholesterol level high enough to seek medical help.
There are two types of cholesterol that affect your risk of heart disease. Low-density lipoprotein (a lipoprotein is the lipid-protein combination that creates cholesterol), or LDL, is the bad cholesterol. LDL, says Balady, is the "culprit molecule" that creates an inflammatory response in blood vessels, leading to cholesterol buildup along artery walls. High-density lipoprotein, or HDL, is the good cholesterol, responsible for removing cholesterol from artery walls and carrying it to the liver for processing. A high level of HDL, coupled with a low level of LDL, is healthy.
While HDL cholesterol is good, there is "no great way to raise HDL levels," says Balady. Regular exercise can raise it by two to five points, but there is no dramatic increase. Estrogen replacement therapy in postmenopausal women has been shown to raise HDL levels by up to 15 percent. Medications can also raise HDL, but Balady says none are currently being prescribed to do so. He also says that a low-fat, low cholesterol diet, which is prescribed for people with high LDL levels, can actually lower HDL.
Because of its relationship to heart disease, "we [physicians] currently target LDL in our treatment of high cholesterol," says Balady. Lowering LDL is especially important in people with other risk factors for heart disease, including a family history, cigarette smoking, hypertension, and diabetes.
A person's total blood cholesterol level, determined through a simple blood test, is given as a certain number of milligrams of cholesterol per deciliter of blood. A total blood cholesterol of under 200 mg/dl is considered normal, while 200 to 240 mg/dl is borderline. Anything over 240 mg/dl is considered high. Physicians like to see LDL levels close to 100 -- or at least under 125 -- in individuals who have known heart problems. For individuals with no heart disease risk factors, physicians don't often prescribe treatment (exercise, diet, and/or medications) until LDL levels reach 190. The goal then is to lower the LDL level to below 160.
"Clearly, we [physicians] are more aggressive in treating patients with high cholesterol levels who have heart disease or who have risk factors for heart disease than we are with those with no known risk factors," says Balady. Cholesterol levels should be checked every five years for individuals with normal baseline readings. If cholesterol levels are elevated, they should be checked every six months until the level decreases.
"Health Matters" is written in cooperation with staff members of Boston Medical Center. For more information on cholesterol or other health issues, call 638-6767.