(MayoClinic.com) Your doctor says you need to lower your low-density lipoprotein (LDL) cholesterol, what's often called the "bad" cholesterol. You're working hard at that goal, but now your doctor says it's important to raise your high-density lipoprotein (HDL) cholesterol, which is known as the "good" cholesterol. It might sound like a mixed message, but this one-two punch — reducing LDL cholesterol and increasing HDL cholesterol — is a great way to lower your risk of heart disease.

Cholesterol is a waxy substance that's found in all of your cells and has several healthy functions, including helping to build your body's cells and playing a role in the production of sex hormones. It's carried through your bloodstream attached to proteins. These proteins are called lipoproteins.

• Low-density lipoproteins. These lipoproteins carry cholesterol throughout your body, delivering it to different organs and tissues. But if your body has more cholesterol than it needs, the excess keeps circulating in your blood. Over time, circulating LDL cholesterol reduces in size and undergoes chemical changes (becomes oxidized). These smaller, denser particles more easily enter the blood vessel wall and start to build up under the vessel lining. Deposits of LDL cholesterol particles are called plaques, and they can lead to inflammation, bleeding into the area, and calcification. Eventually, plaques can start to crowd the space within the blood vessel and obstruct blood flow, causing coronary artery disease. This is why LDL cholesterol is often referred to as "bad" cholesterol.
• High-density lipoproteins. These lipoproteins are often referred to as HDL, or "good," cholesterol. They act as cholesterol scavengers, picking up excess cholesterol in your blood and taking it back to your liver for disposal. The higher your HDL level, the less "bad" cholesterol you'll have in your blood. In addition, HDL may have other protective effects on your heart and blood vessels, including antioxidant, anti-inflammatory and anti-clotting effects.

The message to lower LDL cholesterol is loud and clear — but it might not be enough for people at high risk of heart disease. So doctors are beginning to turn their attention to HDL cholesterol. The evidence so far looks good that increasing HDL cholesterol reduces your risk of dying of heart disease.

Cholesterol levels are measured in milligrams (mg) of cholesterol per deciliter (dL) of blood, or millimoles (mmol) per liter (L). When it comes to HDL cholesterol, think high. Most people should aim for an HDL level of 60 mg/dL (1.6 mmol/L) or above. An HDL level below 40 mg/dL (1.0 mmol/L) increases the risk of heart disease.

For the average man, HDL cholesterol ranges from 40 to 50 mg/dL (1.0 to 1.3 mmol/L). Thanks to female sex hormones — which have a positive effect on HDL cholesterol — the average woman fares better, with HDL cholesterol ranging from 50 to 60 mg/dL (1.3 to 1.6 mmol/L). But both men and women can benefit from increasing these levels.

If you don't know your HDL level, ask your doctor for a baseline cholesterol test. If your HDL value isn't within a desirable range, your doctor may recommend lifestyle changes to boost your HDL cholesterol.

What's your HDL cholesterol level?

*mg/dL = milligrams per deciliter

**mmol/L = millimoles per liter

Your lifestyle has the single greatest impact on your HDL cholesterol. Even small changes to your daily habits can help you meet your HDL target.

• Don't smoke. Smoking lowers HDL cholesterol and increases your blood's tendency to clot. It also causes chemical changes to HDL, which may eliminate HDL's beneficial effects. If you smoke, quit. Quitting smoking can increase your HDL cholesterol by up to 10 percent. Quitting isn't always easy, but you can increase your odds of success by trying more than one strategy at a time. For example, combine medication to reduce nicotine cravings with a support group or individual counseling. Talk with your doctor about your options for quitting.
• Maintain a healthy weight. Excess pounds take a toll on HDL cholesterol. But there's good news. If you're overweight, losing even a few pounds can improve your HDL level. For every 2 pounds you lose, your HDL may increase by 0.35 mg/dL (0.01 mmol/L). That's about 1 mg/dL (0.03 mmol/L) for every 6 pounds. If you focus on becoming more physically active and choosing healthier foods — two other ways to increase your HDL cholesterol — you'll likely move toward a healthier weight in the process. What a bonus.
• Get more physical activity. Within two months of starting, frequent aerobic exercise can increase HDL cholesterol by about 5 percent in otherwise healthy sedentary adults. Your best bet for increasing HDL cholesterol is to exercise briskly for 30 minutes, five times a week, so that you get more than 120 minutes of brisk aerobic exercise a week. Aerobic exercise is the kind that increases your heart rate and maximizes the amount of oxygen in your blood. Examples of aerobic exercise include walking, running, cycling, swimming, playing basketball, raking leaves — anything that increases your heart rate.
• Choose healthier fats. A healthy diet includes some fat, but there's a limit. In a heart-healthy diet, between 25 and 35 percent of your total daily calories can come from fat — but saturated fat should account for less than 7 percent of your total daily calories. Avoid foods that contain saturated and trans fats, which raise LDL cholesterol and worsen inflammatory effects. Trans fat is found in many margarines and commercial baked products, and anything that contains partially hydrogenated vegetable oil. On the other hand, monounsaturated and polyunsaturated fats — found in olive, peanut and canola oils — tend to improve HDL's anti-inflammatory abilities. Nuts, fish and other foods containing omega-3 fatty acids are other good choices for improving your LDL cholesterol to HDL cholesterol ratio.
• Drink alcohol only in moderation. In some studies, moderate use of alcohol has been linked with higher levels of HDL cholesterol — but the benefits aren't strong enough to recommend alcohol for anyone who doesn't drink already. If you choose to drink alcohol, do so in moderation. This means no more than one drink a day for women, and one to two drinks a day for men.

Some medications used to lower LDL cholesterol may also increase HDL cholesterol, including niacin, fibrates (Lopid, others) and statins (Lipitor, Zocor, others). Niacin is the most effective of these medications, increasing HDL cholesterol by up to 30 percent.

Researchers continue to study other options for increasing HDL's beneficial effects on the heart and blood vessels. In particular, they're interested in exploring not just how to increase HDL cholesterol but how to expand its protective functions and minimize potentially negative effects. In the meantime, lifestyle changes will help you on your way to an optimal HDL level.

If your doctor prescribes medication to help control your cholesterol, take it as directed while you continue to focus on a healthy lifestyle.

A number of dietary supplements may have a healthy effect on blood cholesterol levels. Some for which current evidence suggests possible benefits include plant sterols such as beta-sitosterol and sitostanol (typically found in margarine spreads such as Promise activ or Benecol), omega-3 fatty acids (fatty fish, fish oil supplements), and flaxseed oil or grain. If you're currently taking medications, talk to your doctor before starting any supplement, to avoid potentially harmful interactions.

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