I've noticed many vitamins i take are not fda approved such as calcium. does this mean they're not good or don't work? are vitamins fda approved?

FDA does not approve: The fda does not "approve" vitamins though the fda does regulate vitamins- see http://www.Fda.Gov/aboutfda/transparency/basics/ucm194344.Htm this does not mean they are not good. Over 100, 000 people die in the us each year from taking properly prescribed fda-approved drugs. There are no known deaths reported from vitamins in recent years. Fda approval does not mean something is safe!