As beverage-makers continue to develop products that do more than satisfy consumers’ thirst, the number of beverages that carry a functional claim continues to increase. According to “Functional and Natural Ready-to-Drink Beverages in the U.S.,” a report by Rockville, Md.-based market research publisher Packaged Facts, sales of energy drinks, ready-to-drink (RTD) teas and sports drinks have helped the functional and natural RTD beverage market grow to $23 billion.