Dietary supplements do not need to be pre-approved by the fda before being placed on the market. In 2007 the fda â€˜s "current good manufacturing practices" (gmp) policy took effect to ensure that supplements "are produced in a quality manner, do not contain contaminants or impurities, and are accurately labeled" . You can use a search engine to pull up a list of vitamin / supplement companies that are gmp certified. A doctor i work with recently attended a conference that recommended natureâ€™s bounty brand because their doses are standardized.
I hope this information is helpful for you.