The risk of developing coronary heart disease increases as your blood cholesterol rises. This is why it is so important that you have your cholesterol level measured. Currently, more than half of all adult Americans have cholesterol levels of 200 mg/dl or greater, which places them at an increasing risk for coronary heart disease. A very large percentage of the adult population 20 years of age or older has blood cholesterol levels that are considered "high," that is, 240 mg/dl or greater. A blood cholesterol level of 240 mg/dl or greater is considered high. But any level above 200 mg/dl, even in the "borderline-high" category increases your risk for heart disease. If your blood cholesterol is 240 mg/dl or greater, you have more than twice the risk of someone whose cholesterol is 200 mg/dl.

Most coronary heart disease is caused by arteriosclerosis, which occurs when cholesterol, fat, and other substances build up in the walls of the arteries that supply blood to the heart. These deposits narrow the arteries and can slow or block the flow of blood. Among many things, blood carries a constant supply of oxygen to the heart. Without oxygen, heart muscles weaken, resulting in chest pain (angina), a heart attack (myocardial infarction), or even death. Arteriosclerosis is a slow progressive disease that may start very early in life yet may not produce symptoms for many years. 

Lowering your high blood cholesterol level will slow fatty build up in the walls of the arteries and reduce your risk of a heart attack and death caused by heart attack. In fact, some studies have shown that in adults with "high" cholesterol levels, for each one percent reduction in total cholesterol levels, there is a two percent reduction in the number of heart attacks. In other words, if you reduce your cholesterol level 15 percent, your risk of coronary heart disease could drop by 30 percent.