The main cause of stroke may surprise you.Stroke is the third leading cause of death in the U.S. Also known as a brain attack, a stroke happens when blood flow is cut off from the brain, causing brain cells to die. It can lead to brain damage, vision or speech problems, paralysis and even death. And, the main cause of stroke may surprise you. Most strokes are caused by hard arteries, a blood vessel issue that typically shows no symptoms. Dr. Mohammad Eslami joins Dr. Roizen to explain how to prevent cardiovascular trouble that can destroy your brain. Bonus! This Gut Condition Could Cost You Your Colon