Slightly fizzy with a vinegar-like tang, this fermented black tea beverage has been around for centuries. Lab reports and animal studies show it to be a potent antioxidant and immune system stimulator, but scientific evidence in humans is lacking. Still, with a taste reminiscent of sixties soda, we’re kind of partial to Synergy Grape Chia. Omega-3 rich chia seeds add fun texture and fiber, the yeasty taste is subtle, and the sugar content (1 teaspoon per cup) is far lower than most.Bottom Line: At nearly $4 a bottle, it’s a splurge rather than a necessity. Caution: experts say don’t drink this acidic tea if you have weakened immune function or are taking drugs that need normal pH levels in the stomach to be absorbed.