Cholesterol: The Good, The Bad, The Ugly

I'm often asked about the different types of cholesterol, and what it all means to your health. Cholesterol is a soft, waxy substance found among the lipids (fats) in the bloodstream and in all your body's cells.

Cholesterol is an important part of a healthy body, because it's used to form cell membranes and some hormones. It is also needed for other functions in your body, but a high level of cholesterol in the blood -- hypercholesterolemia -- is a major risk factor for coronary heart disease (which leads to heart attack). According to current estimates, nearly 62 million Americans have one or more forms of cardiovascular disease (CVD).

Cholesterol and other fats can't dissolve in the blood. They have to be transported to and from the cells by special carriers called lipoproteins. There are several kinds of lipoproteins, but the ones to be most concerned about are low-density lipoprotein (LDL) and high-density lipoprotein (HDL).

What are the different types of cholesterol?

HDL cholesterol is also known as HDL, HDL-C, or "good" cholesterol. About 1/3 to 1/4 of blood cholesterol is carried by high-density lipoprotein, or HDL. Medical experts think HDL tends to carry cholesterol away from the arteries and back to the liver, where it's passed from the body. Some experts believe HDL removes excess cholesterol from plaques -- thus slowing their growth. HDL cholesterol is known as "good" cholesterol, because a high HDL level seems to protect against heart attack. The opposite is also true: a low HDL level (less than 40 mg/dL) indicates a greater risk. It may also raise your risk for having a stroke.

What is LDL cholesterol?

Low-density lipoprotein is the major cholesterol carrier in the blood. If too much LDL cholesterol circulates in the blood, it can slowly build up in the walls of the arteries feeding the heart and brain. Together with other substances, it can form plaque, a thick, hard deposit that can clog those arteries.

This condition is known as atherosclerosis. A clot that forms near this plaque can block the blood flow to part of the heart muscle and cause a heart attack. A high level of LDL cholesterol (160 mg/dL and above) reflects an increased risk of heart disease. That's why LDL cholesterol is often called "bad" cholesterol. Lower levels of LDL cholesterol reflect a lower risk of heart disease.

What is Lp(a) cholesterol?

Lp(a) is a genetic variation of plasma LDL. A high level of Lp(a) is an important risk factor for developing atherosclerosis prematurely. How an increased Lp(a) contributes to heart disease isn't clear. The lesions in artery walls contain substances that may interact with Lp(a), leading to the buildup of fatty deposits.

What about cholesterol and diet?

People get cholesterol in two ways. The body -- mainly the liver -- produces varying amounts, usually about 1,000mg per day. Another 400 to 500mg (or more) can come directly from foods. Foods from animals (especially egg yolks, meat, poultry, fish, seafood and whole-milk dairy products) contain it. Foods from plants (fruits, vegetables, grains, nuts and seeds) don't contain cholesterol.
Typically, the body makes all the cholesterol it needs, so people don't need to consume it. Scientific studies show that diets high in total fat and saturated fat contribute to the high blood cholesterol levels. Both the amount and the type of fat is important in determining how it influences blood cholesterol.
All fat is composed of either saturated or unsaturated fatty acids. Unsaturated fatty acids can be divided into monounsaturated and polyunsaturated fatty acids. Food fats generally contain a mix of these three kinds of fatty acids. If a fat contains a relatively high percentage of saturated fatty acids, it is said to be a "saturated fat" or "highly saturated." It's primarily the saturated fats that are linked to higher blood cholesterol levels.

How does exercise effect cholesterol?

Exercise increases HDL ("good") cholesterol in some people. A higher HDL cholesterol is linked with a lower risk of heart disease. Exercise can also help control weight, diabetes and high blood pressure. Exercise that uses oxygen to provide energy to large muscles (aerobic exercise) raises your heart and breathing rates. Regular exercise, such as brisk walking, jogging and swimming also condition your heart and lungs. In addition, scientists have discovered it makes cholesterol less dangerous. A new study found that even modest exercise changes the size and density of cholesterol-carrying proteins, so they do less damage. And the benefits occur even if a person's total amount of cholesterol and weight stay the same.

Smoking, Alcohol and Cholesterol

Alcohol does not lower blood cholesterol levels, but some evidence suggests one to two glasses of wine daily can raise the level of HDL cholesterol, the good kind of cholesterol that helps protect against heart disease. However, use of alcohol in excess of this amount can damage the liver, raise blood pressure, and raise blood levels of triglycerides, another type of fat.

Alcohol is also a concentrated source of calories and can contribute to weight gain. For these reasons, coupled with increased risk of alcoholism, suicide, and accidents, alcohol should not be used as a means to lower blood cholesterol. The American Heart Association (AHA) recommends that if you drink alcohol, you do so in moderation.

Cigarette and tobacco smoke is one of the six major risk factors of heart disease that you can change, treat or modify. Smoking has been shown to lower HDL or "good" cholesterol levels.

Even after doing everything right, some people may still need cholesterol-lowering medication. While dietary changes are not enough to significantly lower cholesterol in some people, a combination of healthy eating and taking cholesterol-lowering drugs is more effective than either one alone.