Runa Tea added two unsweetened flavors to its line of guayusa teas: Lime and Guava. According to the company, guayusa tea contains as much caffeine as a cup of coffee and twice the antioxidants of green tea. Guayusa is a native Amazonian tree leaf known for its health benefits, such as immune support, digestive aid, appetite suppression and brain performance, the company says. A 14-ounce bottle has a suggested retail price of $1.99.