HDL cholesterol: How to boost your 'good' cholesterol

High-density lipoprotein (HDL) cholesterol is known as the "good" cholesterol because it helps remove other forms of cholesterol from the bloodstream. A higher level of HDL cholesterol is linked to a lower risk of heart disease.

Cholesterol is a waxy substance that's in every cell in the body. At healthy levels, cholesterol does useful work. This includes helping the body's cells work as they should. HDL moves through the bloodstream on proteins called lipoproteins.

The two main types of lipoproteins that carry cholesterol are:

• Low-density lipoprotein (LDL) cholesterol. High levels of LDL can build up within the walls of the blood vessels over time. This narrows the passageways.

  Sometimes a clot forms and gets stuck in the narrowed space. This causes a heart attack or stroke. This is why LDL cholesterol also is called the "bad" cholesterol.

• High-density lipoprotein cholesterol. HDL cholesterol is often called the "good" cholesterol. HDL cholesterol picks up excess cholesterol in the blood. It carries the cholesterol back to the liver. After the liver breaks down the cholesterol, the liver flushes it from the body.

If you have high LDL and low HDL cholesterol levels, your healthcare professional looks at lowering your LDL cholesterol first. Medicines known as statins are the most common treatment for high LDL cholesterol. Examples are atorvastatin (Lipitor) and simvastatin (Zocor).

What are optimal levels of HDL cholesterol?

Cholesterol levels are measured in milligrams (mg) of cholesterol per deciliter (dL) of blood or millimoles (mmol) of cholesterol per liter (L) of blood. For HDL cholesterol, higher numbers are better.

People who have naturally higher levels of HDL cholesterol are at somewhat lower risk of heart attack and stroke. It's less clear whether the same is true for people who raise their HDL cholesterol levels with medicines.

Lifestyle changes known to increase HDL cholesterol have been shown to lower the risk of heart attack. These changes include moving more, quitting smoking, and eating a diet rich in vegetables, fruits and whole grains. But medicines used just to increase HDL cholesterol levels have not lowered the rate of heart attack.

Oddly, people who have very high HDL cholesterol levels naturally seem to be at higher risk of heart disease. Extremely high HDL cholesterol is a level above 100 mg/dL (2.5 mmol/L). Genes may be the cause of very high HDL cholesterol.

Make your lifestyle count

HDL cholesterol levels are often lower in people who have metabolic syndrome. This is a group of conditions that includes obesity, increased blood pressure and high blood sugar levels.

Increased physical activity can raise HDL cholesterol levels while lowering levels of triglycerides, the most common type of fat in the body. As little as 60 minutes of moderate-intensity aerobic exercise a week can achieve this. Moving more also can help you lose weight.

Try not to include trans fats in your diet. Trans fats can increase LDL cholesterol and lower HDL cholesterol levels. Foods made with shortening, such as cakes and cookies, often contain trans fats. So do most fried foods and some margarines. Also limit saturated fat, found in meats and full-fat dairy products.

If you smoke, find a way to quit. Smoking lowers HDL levels, especially in women. And it may raise LDL cholesterol and triglyceride levels.

Moderate use of alcohol has been linked with higher levels of HDL cholesterol. For healthy adults, moderate drinking means up to one drink a day for women and up to two drinks a day for men.

However, if you don't drink alcohol, don't start drinking to raise your HDL cholesterol levels. Too much alcohol can cause weight gain. And it might increase your blood pressure and triglyceride levels and raise your risk of certain cancers.

Medicines can boost HDL cholesterol

Medicines used to lower LDL cholesterol and triglyceride levels sometimes improve HDL cholesterol levels. These include prescription niacin; fibrates such as gemfibrozil (Lopid); and certain statins, such as simvastatin and rosuvastatin.

But clinical trials haven't shown that increasing HDL cholesterol levels with medicines reduces the risk of heart attack. So your healthcare professional is likely to suggest boosting HDL cholesterol with lifestyle changes instead.