I learned today thanks to my daily dose of Financial Times that there is a category called 'functional food and drinks'. It sounds a bit dry to me.
Health Kick a new drink from UK based Firefly Tonics illustrates the topic better than any grand category.
As for Firefly Tonics with their Shiny Happy People labels ( as seen here) and light touch, I would put them in the Fun & Health Drinks category...more surf than merchandising.
In the US , Firefly Tonics are available at Whole Foods and Wild Oats. For other countries check the list.
I previously wrote about Innocent Drinks also from the UK.