Any health-food junkie knows that if you're looking for a sweet treat, dark chocolate is the way to go. The secret to its reputation as a superfood: cacao beans. They've got the highest concentration of antioxidants of any known food, according to Brad Gruno, founder of Brad's Raw Foods. To reap the most benefits, pick a bar that's 70% dark or higher. Just keep in mind that the darker it is, the more bitter it will taste.