Cocoa contains approximately 43.6 mg of flavonoids per gram. Flavonoids are part of a powerful group of antioxidants known as polyphenols, and according to Medical News Today, cocoa is one of the highest polyphenol-containing foods. In addition, hot cocoa contains more antioxidants per cup than a serving of red wine or tea, and Science Daily explains it may even be the healthiest choice of the three.