Montana University finds "convenience teas" have equal healthiness to fresh-brewed.
An interesting conclusion by Montana State, published in Prevention, June 2002, found that premade teas can still be potent and full of antioxidants on a level near-equivalent to fresh-brewed tea:
"In fact, most homemade iced tea (hot-brewed and fridge teas) did have more antioxidants than most convenience teas. So if you want the very max, make your own.
But we discovered that some convenience iced teas still retained spectacular antioxidant levels. Beating even Concord grape juice, the all-time antioxidant superstar among fruits and vegetables, were Nestea Liquid Concentrate Iced Tea (green tea with honey), Honest Tea Moroccan Mint (bottled green tea), and Lipton Iced Tea (bottled, sweetened, without lemon). Lipton Cold Brew tea bags even outscored the fruit that's highest in antioxidants: blueberries.
What's the explanation? "Antioxidant levels in any given tea can vary from batch to batch," because of different growing conditions and manufacturing procedures, says Peter Goggi, president of the Royal Estates Tea Company, the tea-buying division of Lipton in Englewood Cliffs, NJ. That's why antioxidant levels in individual samples of convenience teas can rival tea bag-brewed tea, as they did in our test.
But the health benefits of convenience iced teas don't depend on the luck of the draw. Here's our best discovery of all: Even the lowest-scoring convenience iced teas contained at least as many antioxidants as fruits and veggies such as strawberries and spinach! That means if it's easier for you to drink a convenience iced tea, go ahead!"