Walk through the giant fiberglass heart at Philadelphia's famed science museum, the Franklin Institute, and you get a good idea of what your heart does all day. Arrows guide you through the two-story-high heart, as you follow the flow of blood that surges toward lungs and arteries with every beat. The blood enters the right atrium that pumps it to the right ventricle, which squirts blood to the lungs where it picks up oxygen. The blood then enters the left atrium from which it flows into the left ventricle, the muscular pumphouse that sends newly oxygenated blood surging through blood vessels to the rest of the body.

Every part of you needs oxygen-rich blood to stay alive, and so does the heart itself. It comes equipped with three special blood vessels that keep it supplied. Shaped like the tubes on a coronet, they're known as coronary arteries.

Normally, the insides of your coronary arteries are slick and even, so blood flows smoothly to your heart. When you have heart disease, though, the inside of the arteries gets clogged with a waxy mixture of cholesterol and other substances, called plaque, that limits blood flow. Now the blood looks as if it's surging through rapids. If the flow gets dammed up altogether, the result is a heart attack.

Your heart isn't the only organ that can be affected by this pernicious clogging. The arteries to your brain and other key body parts, like your legs, can also get clogged with plaque. Cut off the blood flow to your brain, and the result is a stroke. Limit the flow to your legs, and you're almost guaranteed to have chronic cramps and leg pain. In men, too little blood flowing to the penis can cause another related problem—impotence.

Plaque gets a foothold when a certain type of cholesterol normally found in your blood—a type called low-density lipoprotein (LDL)—accumulates inside the arteries. Some research suggests that plaque is more likely to do this if the lining has been damaged. Once inside the artery wall, LDL can undergo a nefarious transformation called oxidation that makes it highly dangerous. Oxidized LDL causes inflammation and triggers a series of changes that usher immune cells and blood-clotting proteins into your arteries, where they turn into the sticky, messy play-school paste called plaque.

So anything that helps LDL to oxidize is the enemy. And among the enemy's forces are a breed of marauding opportunists called free radicals. Unstable molecules that are the unfortunate by-products of breathing and other essential metabolic processes, free radicals are what oxidize LDL.

Smoking, which unleashes extra free radicals in your body, seems to step up oxidation of LDL. So do elevated blood sugar levels associated with diabetes. It's obvious, then, that you should quit smoking if you smoke, and take care of your diabetes if you have diabetes, as your first measures to control heart disease.

What You Need to Know about Niacin Inexpensive and readily available in health food stores, niacin in high doses can lower your "bad" low-density lipoprotein (LDL) cholesterol and triglyceride levels while giving your "good" high-density lipoprotein (HDL) cholesterol level a boost. Sounds ideal—but it can also be extremely dangerous. To get the benefits of niacin therapy, you have to take amounts that may be hundreds of times higher than the Daily Value, says Ira S. Ockene, M.D., professor of medicine at the University of Massachusetts Medical School in Worcester. At these high levels, niacin may cause liver toxicity and other side effects. And a high dose of niacin can worsen diabetes. "Niacin is a very good drug, but it's a real drug and at these dose levels can cause lots of side effects," he notes. "You shouldn't use it if you don't have a physician monitoring you."

Product Recommendations For Healthy Skin & Heart. Each tablet of Flush Free Niacin contains: 500 mg Niacin (from Inositol Hexaniacinate Niacin in a flush-free from) (B-3) Each Capsules contains: 100 mg of Niacin