Most heart disease is caused by atherosclerosis, which occurs when cholesterol, fat, and other substances build up in the walls of the arteries that supply blood to the heart. These deposits, called plaque, narrow the arteries and can slow down or block the flow of blood. One of the most important functions of blood is to carry a constant supply of life-giving oxygen to the heart. Without oxygen, heart muscle tissues are gradually destroyed, resulting in chest pain (angina), a heart attack (myocardial infarction), or even death. In the same manner, a buildup in the arteries supplying blood to the brain can cause a stroke. Atherosclerosis is a slow progressive disease that may start very early in life yet might not show symptoms for many years.

When high blood cholesterol is combined with other major risk factors, the chance that you'll suffer from heart disease increases even further. For example, if your cholesterol level is in the High category and your blood pressure is elevated, your risk for heart disease increases six times. If you also smoke, your risk increases more than twentyfold.

What You Can Do

Here are the current AHA recommendations:

• If you are a healthy adult over 20, test your blood cholesterol levels at least once every five years.
• Eat no more than 300 milligrams of cholesterol a day. One egg yolk has about 213 milligrams of cholesterol. Egg whites, on the other hand, have no cholesterol or fat and are a great source of protein. You can substitute two egg whites for each egg yolk in many recipes that call for eggs.
• Limit your total fat intake to less than 30 percent of calories, with less than 10 percent coming from saturated fats. You can accomplish this by:
• Choosing more fruits, vegetables and whole grains instead of fatty meats and bakery goods.
• Eating fish, poultry without skin and lean meats instead of fatty ones.

• Consuming low-fat or skim milk dairy products instead of whole milk dairy

Getting an Accurate Reading

Getting an accurate cholesterol reading can be tricky. The tests themselves -- particularly those done outside a doctor's office, laboratory, or other medical setting -- may be imprecise. But even with the best testing equipment, blood sample results can vary nearly 20 percent depending on the time of day, what you've eaten, and whether you've exercised recently. Here's how to maximize the chance of getting accurate readings:

• Ask if the laboratory processing your blood conforms to standards set by the Centers for Disease Control (CDC). If it doesn't, try to use a different lab.
• Remind your doctor about any medications you're taking. Many drugs, such as blood-pressure medications and birth-control pills, can affect cholesterol levels.
• Sit calmly for ten minutes before your blood is drawn. Your posture and any abrupt changes in position can affect the results.
• If you're having blood drawn from your arm, make sure the tourniquet stays on for no more than one minute. Any longer may boost cholesterol readings by as much as 15 percent.
• In the 12 hours prior to your test consume only water. Avoid strenuous exercise for 24 hours before testing.
• Confirm any abnormal or borderline readings by taking a second test and averaging the findings. If the lower reading of total cholesterol is more than 14 percent below the higher reading, have a third test and average the results of all three. Do the same if the lower reading for HDL, LDL or triglycerides is more than 24 percent below the higher reading. Tests should be done at least one week apart, but within two months.