High cholesterol can build up even in trim, active people. If you are active and young enough to think that "middle age" begins at 60, you're probably a baby boomer who never thought you'd need to worry about high cholesterol. That's something that happens to "older" people, but not you!

The truth is, if you're 45 to 60 -- or even younger -- you're at risk. The American Heart Association reports that some 107 million Americans have borderline high or higher cholesterol levels. Experts say that ignoring even slightly elevated cholesterol levels may be a setup for disaster. In at least one major worldwide study of some 29,000 men and women, researchers found that an elevated cholesterol level was among the top risk factors for heart attack. Studies also show that lowering your cholesterol can reduce your risk of having a heart attack by as much as 40%.

Cholesterol is a soft, fat-like substance produced in the liver. How much cholesterol you produce is affected by your genes and by what you eat. And at least some cholesterol is essential for good health.

Here are a few basic facts. Cholesterol comes in two main forms:

Low density lipoprotein or LDL -- the "bad" cholesterol which can build up in artery walls, causing inflammation and clot formation.

High density lipoprotein or HDL -- the "good" cholesterol that helps remove LDL and carry it to the liver, where it's processed and eliminated.

You'll also hear about total cholesterol levels, which are made up of LDL, HDL, and other blood fats. You also have triglycerides, another blood fat, which are also linked to heart disease and stroke. These numbers can get confusing. The bottom line? You want high HDL and low triglycerides and LDL. When HDL levels are high and LDL levels are low your body is likely maintaining just the right amount of cholesterol necessary for good health.

Unfortunately, it often doesn't take much for this delicate balance to go awry, particularly as you age. Some folks are simply genetically prone to making too much LDL. They aren't overweight, they exercise regularly, but as they get older HDL goes down and LDL goes up, and they just make too much cholesterol. If you're one of them, you probably will need to eat a careful low-fat diet and take medication eventually. For the rest of us, experts say we are driving our cholesterol up with a rich, high-fat diet and a lack of exercise. In the process, we're putting our hearts at risk.

What are the specific dangers? When LDL rises too high, it collects and sticks inside artery walls. This contributes to clot formation, and increases the risk of heart attack and stroke. It can also cause blood vessels to become stiff and hard, which, in turn, increases the risk of high blood pressure.

Moreover, the latest research shows that LDL cholesterol also inflames artery walls, causing a release of chemicals that may be directly related to heart attack and even sudden death.

Although cholesterol is a leading factor in heart disease on its own, it's not a completely accurate predictor of heart disease risk. It's just one factor of many risk factors that may eventually lead to heart attack. It must be viewed in concert with what else is going on in your body -- your weight, body shape, blood pressure, and fitness level -- in order to obtain a true picture of heart health.

New, more sophisticated tests are also attempting to tease out the actual size of cholesterol particles in the body, which can make a difference in your risk. In studies thus far, large pieces of LDL cholesterol appear to be less dangerous for the heart than tiny particles, which sneak in under the lining of an artery and lead to inflammation.

Nonetheless, your cholesterol counts. So it's important for adults to know their total cholesterol count, as well as their LDL, HDL and triglyceride levels. Call your doctor to get your numbers from your last physical when you had blood work done. Then, compare them to these risk levels from the American Heart Association:

Total Cholesterol

Most Desirable: Less than 200 mg/dL

Risky: 200 to 239 mg/dL

Danger Zone: 240 mg/dL or more

LDL Cholesterol

Most Desirable: Under 100 mg/dL

Desirable: 100 to 129 mg/dL

Borderline: 130 to 159 mg/dL

Risky: 160 to 189 mg/dL

Danger Zone: 190 mg/dL or over

HDL Cholesterol

Most Desirable: 60 mg/dL or higher

Risky: Less than 40 mg/dL

Triglycerides

Most Desirable: Under 150 mg/dL

Risky: 150 to 199 mg/dL

Danger Zone: 200 mg/dL or higher

If your HDL is low and your LDL is high, your first line of defense is to change your diet -- a strategy that can bring results in as little as eight to 12 weeks. The first foods to cut are the ones high in saturated fat. These are fats that come from animal products, like beef, lamb, and pork, as well as high-fat dairy products such as butter, ice cream, high-fat yogurt or whole milk.

Equally important, replace tropical oils in your diet such as palm, corn, and coconut oils with heart-healthy oils such as olive, canola, or grape seed oil.

This allows you to shift the fat content, which lowers LDL and raises HDL. Lower LDL by increasing soluble fiber, up to 25 grams a day, and adding soy-rich foods such as tofu and soy milk.

To increase HDL. omega-3 fatty acids -- the good fats found in flax seed oil, walnuts, almonds, and fish such as salmon, are recommended. Avoid foods that raise triglycerides, such as simple carbohydrates like white bread, cakes, cookies, and pies, as well as french fries and donuts.

Most people make cholesterol out of animal fat, not from cholesterol-rich foods such as eggs or shrimp. But some people are more genetically programmed to make bad LDL cholesterol out of those cholesterol-rich foods. It's wise for everyone with high cholesterol to keep these foods to a minimum.

In addition, the American Heart Association says adding the following foods to your diet can also help lower your cholesterol:

5 servings or more of fresh fruits and vegetables daily.

6 or more servings per day of whole-grain, high-fiber products, including whole-wheat breads and cereals, oatmeal, and brown rice.

Protein consisting of skinless poultry, very lean meats, fish and legumes (beans).

Fat-free and low-fat dairy products.

In addition to dietary measures, many doctors now recommend the use of "natural plant sterols" to help raise HDL.

They work by competing with human cholesterol, keeping it from getting into our blood vessels where clots can form. Instead, LDL is shuttled off to your liver where it's metabolized and eliminated. Results can be seen in about three weeks.

Cholesterol-lowering margarines containing plant sterols and stanols include Benecol and Take Control.

Try as you might, even if you do everything right, your cholesterol may stubbornly remain high. When this is the case, doctors say cholesterol-lowering medications are in order.

Currently, there are five such classes of drugs, nearly all focused on reducing LDL. By far, however, the most frequently prescribed are drugs known as statins. These work to slow the body's production of cholesterol and increase the liver's ability to remove LDL from your bloodstream. They can also reduce triglyceride levels and can offer a modest increase in HDL.

This group includes:
    Crestor
    Lescol
    Lipitor
    Mevacor
    Pravachol
    Zocor

Like all drugs, these medications can cause some side effects: muscle aches and weakness, mild stomach upset, gas, and nausea. More serious but rare problems include liver damage or muscle breakdown. Regular follow-up with your physician is needed; let your health care provider know your symptoms and always have a list of your medications with you. Still, doctors say side effects are uncommon and in the overwhelming majority of people, benefits far outweigh risks. Pregnant woman should not take these medications.

The bottom line: The data on safety and effectiveness of even aggressive medical therapy is good. Most people get good results from the medication without significant problems.

According to the American Heart Association, other cholesterol-lowering medications sometimes used alone, or more frequently in conjunction with statins, include:

    Bile acid resins (cholestyramine and colestipol).
    Fibrates (such as gemfibrozil and fenofibrate)
    Cholesterol absorption inhibitors (Zetia).
    Nicotinic acid -- also known as niacin -- in prescription-strength doses.

While doctors enthusiastically agree medications can help, taking medication won't let you enjoy a rich diet without worry. You can outeat any medication your doctor can prescribe. These drugs are not a license to eat what you want. Indeed, experts say it's vital to maintain strict dietary and lifestyle changes even when your cholesterol begins to drop.

The more you can do on your own, without medication, the less medication you'll need to remain healthy.