Coffee has been a functional drink probably for as long as it has been in existence, thanks to its natural caffeine content, which has made it a beloved source of energy in the morning. But, coffee has never been much of a player in the functional beverage market partly because its own health status has been questioned over the years. This situation is starting to change, and Starbucks' recent launch of Protein Blended Cold Brew is a sign that coffee may be emerging as the next hot functional beverage platform.