Chocolate Heart Chocolate may be heart smart. Several studies in recent years have found that cocoa, a main ingredient in chocolate, contains large amounts of antioxidant-rich compounds called flavonoids, which act to relax the blood vessels and lower blood pressure. Many other foods, including broccoli, onions, grapes, and tea, also have flavonoids, though none are as packed with the antioxidants as cocoa. Dark chocolate retains far more flavonoids than does milk chocolate, and one German study found that eating 3.5 ounces of dark chocolate per day is as clinically effective at reducing blood pressure as beta-blocker drugs. So, by eating a piece of dark chocolate this Valentine's Day, you may actually be benefiting your heart.