Research is coming to light that antioxidants in food and drinks are not useful to aid health, and may actually be damaging to us.
Antioxidants have been put in food for many years as preservatives, to make our foot last longer. However, recently companies have realised they can re-label these preservatives as "antioxidants" to make people think that they are improving our health. Most of these claims are nonspecific, falling short of making any definite claims that can be tested to back them up.
A recent BBC program tested supposedly antioxidant rich drinks, and found that most contained no more antioxidants than orange juice. They then showed that when people ingested antioxidants, the body does not make use of them for their ability to absorb free radicals, but rather it probably converts them to other useful chemicals. Balanced against the amount of sugar in the drinks (in some cases more than in a can of coke), the conclusion was that they should only be consumed in moderation.