Heart disease is the No. 1 cause of death in the United States and around the world. The good news is that many heart disease deaths are preventable. A healthy diet and lifestyle can help.

Heart disease, or cardiovascular disease, refers to conditions that affect the heart. It can occur when fat, cholesterol, and other substances build up on the blood vessel walls that supply blood to the heart. This can reduce blood flow. If untreated, it may cause a heart attack.