A. Jeffrey B. Blumberg, PhD, director of Tufts HNRCA Antioxidants Research Laboratory, says that yes, green-tea drink mixes do contain health-promoting flavonoids, mostly compounds called catechins-but not much compared to brewed tea. One popular drink-mix brand, for example, says on the label, Contains 63 milligrams catechins from green tea extract.
By comparison, says Blumberg, The total flavonoid content of a 200-milliliter (a little less than 7 fluid ounces) cup of green tea is approximately 267 milligrams, most of which are catechins. So the catechins in this drink mix are equivalent to those in just less than a quarter-cup of brewed green tea. On the other hand, if you want to drink four to eight glasses of this formulated beverage per day…. If you want flavonoid-rich iced tea (green, oolong or black), brew it yourself at double strength and then add ice.