What does science say about the ingredients in functional beverages?

Functional beverages — or drinks promoted as offering mental or physical benefits beyond hydration — are growing in popularity around the world. The Cleveland Clinic says adaptogens are known to trigger chemical reactions that can return the body to a more balanced state. The Cleveland Clinic says probiotics, in theory, work alongside the beneficial microbes in the human body to fight off harmful bacteria, fungi, viruses and parasites. Side effects are rare except for people with weak immune systems, whose bodies might not be able to fight off a probiotic that inadvertently contains harmful microbes.