The Greeks knew it: grapes are the food of the gods. They even named a god, Dionysus, after this ambrosial fruit. Perhaps the Greeks knew what scientists and researchers are just discovering today: Grapes are loaded with flavonoids, including the powerful compounds quercetin, resveratrol, and anthocyanin. These flavonoids are powerful antioxidants that give grapes and other  colorful fruits and veggies their lovely purple color. White grapes also have beneficial properties, but red grapes have...