I'd say that we are a bit antioxidant crazy in our society.
Antioxidants are pushed for everything from stopping the aging process to preventing cancer to enhancing the immune system. You'll find them added to everything from juices to skin creams.
If you don't know what an antioxidant is, it's a substance that helps stop free radicals. Free radicals are missing an electron, so they like to go around and take electrons from other sources, like your cells. This can cause damage to the cells; this process is called oxidation. This damage is believed to be involved in numerous diseases, including heart disease and cancer, as well as aging. Antioxidants are supposed to prevent this damage; they stop the free radicals in their tracks by "appeasing" them with an electron.
In our society, we're all about more is better. More money, more cars, more things...and more antioxidants. We'll take megadoses, hoping that we'll slow the aging process and prevent cancer. We'll rub it all over our skin to prevent wrinkles. We'll put them in our hair to help stop it from turning gray. I'm surprised we aren't using them to prevent another subprime mortgage crisis.
However, just like with anything else, you can have too much of a good thing.
The first sign that too many antioxidants could be a problem was seen in a study published in 1994, where researchers found that smokers who took high doses of beta-carotene (an antioxidant) got more lung cancer than smokers who didn't. A few years later, another study performed at The Fred Hutchinson Cancer Research Center showed the same thing. Further research has confirmed these results.
More research has come out indicating too many antioxidants can be a problem. One meta-analysis (a "study of studies") indicated that high doses of single antioxidants might increase mortality. While this meta-analysis has some flaws, it raises the possibility that you can have too much of a good thing.
Why would too many antioxidants cause a problem? Well, too many antioxidants can have a pro-oxidant effect. This means, rather than stopping oxidation, they contribute to it! Another thought is that, if you take too many antioxidants, you suppress your body's natural antioxidant defense mechanisms.
The old cliche' of "everything in moderation" applies here. Antioxidants in moderation have health benefits, but in excess, they have health detriments. You should get most of your antioxidants from eating a variety of fruits and vegetables. Also, there is nothing wrong with taking a basic multivitamin if you are concerned about deficiencies. But leave the antioxidant supplements on the store counter.