More recent research, though, suggests that it doesn't, and, in fact, that taking a multivitamin can decrease your lifespan.
It's hard to keep up with research results about health, and boy, doesn't it seem like we're given different recommendations every week? But in case you, like me, and like, I fear, those thousands of people who participated in that study I was involved with, had taken the "multivitamins are good" message and stopped paying attention, you may want to reevaluate your choices. Even if you end up deciding that what you're doing now is the right way to go, it's good to do so with updated data.
This Slate article has a bunch of good links to help you do that.