An exerpt that I agree with from Michael Pollan's In Defense of Food :
"We know that people that take supplements are generally healthier than the rest of us, and we also know that, in controlled studies, most of the supplements they take don't appear to work. Probably the supplement takers are healthier for reasons having nothing to do with the pills: They're typically more health conscious, better educated, and more affluent. So to the extent you can, be the kind of person who would take supplements, and then save your money.
That said, many of the nutrition experts I conslted recommend taking a multivitamin, especially as you get older. In theory at least, your diet should provide all the micronutrients you need to be healthy, especially if you're eating real food and lots of plants . . . as we age our need for antioxidants increases while our bodies' ability to absorb them from food declines. So it's probably a good idea, and certainly can't hurt, to take a multivitamin-and-mineral pill after age fifty. And if you don't eat much fish, it might be wise to take a fish oil supplement too."
Here's what I take everyday.