Most vitamins are useless, but here are the ones you should take

It seems like simple, obvious advice: Eat your vegetables, get some exercise, and - of course - take your vitamins.

Or not.

Decades of research has failed to find any substantial evidence that vitamins and supplements do any significant good. In fact, recent studies skew in the opposite direction, having found that certain vitamins may be bad for you. Several have been linked with an increase in certain cancers, for example, while others have been tied to a rise in the risk of kidney stones.

And a large new study out Wednesday suggests that despite this growing knowledge, Americans' pill-popping habits have stayed basically the same over the last decade.

So here are the vitamins and supplements you should take - and the ones you should avoid: