What is a "functional drink" 机能饮料? I spotted this at the 物美 supermarket on 四道口 in Beijing.



(Imgur version.)

Question: What is a "functional drink" 机能饮料?

The translation seems close to correct:


机能 = "function"
饮料 = "drink"


My best guess is that it's a drink suitable for a "function", e.g., a wedding banquet.  But I don't think 机能 has that meaning (it'd be 活动 = "activity").
More commonly known as 機能性飲料, these kinds of "fad" drinks are sold to convey a kind of health benefit, commonly advertised as increasing organ (heart, pancreas, eyes, ...) function. Think herbal or vitamin drinks.