(FORTUNE Magazine) – In May, experts from the National Institutes of Health urged Americans to get aggressive with high cholesterol. If the NIH recommendations are followed, we could see a 25% increase in the number of people on cholesterol-lowering diets, a huge increase in the number who take cholesterol-lowering drugs, and a large dent in the number who die from heart disease, the No. 1 killer in the U.S.

A waxy, fatty substance that circulates in the bloodstream, cholesterol helps with digestion and is converted into hormones. You need some to survive, sure, but your body manufactures all you need. Eat a rich diet, and excess cholesterol is absorbed into the walls of arteries in the heart and elsewhere.

Over time, this cholesterol and other substances build up layers of plaque in the arteries--think of an old pipe slowly clogging. When the arteries in your heart get stopped up--and no blood at all moves through--you're having a heart attack. When the clog takes place in an artery in the neck or brain, it's called a stroke.

Not all cholesterol is the same. Low-density lipoprotein (LDL) cholesterol is "bad" because it travels from the liver to the artery wall, increasing plaque buildup. High-density lipoprotein (HDL) cholesterol is "good" because it does the opposite, removing plaque from the artery wall back to the liver and out of the body. Triglycerides, blood fats that contain 20% cholesterol, also contribute to plaque buildup. The best pattern? A high HDL cholesterol reading and a low count of LDL, triglycerides, and overall cholesterol.

At last look, the average U.S. adult had a total cholesterol reading of 205 milligrams per deciliter, an HDL cholesterol of 45 for men and 55 for women (the result of women's hormonal status before menopause), an LDL cholesterol of 130, and triglycerides of 150. Trouble is, average isn't optimal, and lower is better when it comes to triglycerides and LDL cholesterol. At a minimum, people should shoot for a total cholesterol reading below 200, HDL greater than 45, LDL less than 130, and triglycerides less than 150.

For people with diabetes or multiple risk factors, the new guidelines are even tougher. For them, the goal for LDL cholesterol is now the same as for those who have had a heart attack or coronary artery bypass--less than 100.

LDL cholesterol can be lowered through diet--easy on the meat, high-fat dairy products, egg yolks, tropical oils, and fast foods. And exercising, losing weight, and quitting smoking can increase good HDL cholesterol. Exercise and weight loss will also lower triglycerides. So will consuming less alcohol and sweets.

While I try to help my patients reach their cholesterol targets through diet, medications are sometimes needed. The so-called statin drugs--Baycol, Lescol, Lipitor, Mevacor, Pravachol, and Zocor--are the most effective and generally safe. Other medications can be useful, including Lopid, niacin, Tricor, and Welchol. Still another route is Benecol or Take Control, margarine-like spreads made from plant stanols and sterols--which, believe it or not, can lower total and LDL cholesterol by 10% to 15%.

What does all this mean? First, that many more people should be paying better attention to lifestyle, including diet, exercise, and weight maintenance. It also means that many more people have become candidates for drug treatment to get their cholesterol down, which will make the pharmaceuticals companies happy. Most important, if the guidelines are followed, it means there will be less heart disease, and lives will be saved.

The stakes are too high to gamble--one out of every three people in the U.S. now dies of heart disease. Know your numbers, and see where you fit in the new cholesterol guidelines. Remember, success in prevention is a nonevent. You may never know it was your life that was saved.

For more information on this topic: Go to mayoclinic.com. Mayo Clinic offers Executive Health programs at Mayo Clinics in Jacksonville, Fla.; Rochester, Minn.; and Scottsdale, Ariz.