FDA does not have authorization to review dietary supplements. These products are placed in the food category and not drugs. However, FDA has the authority to stop the sale of a dietary supplement if it is found unsafe for consumption. It can initiate actions against a supplement manufacturer for not complying with the food product manufacturing standards. If a supplement manufacturer finds its product showing side effects, it is required to report it to FDA. These are the reasons there are no FDA approved supplements.
At the same time, it does not mean supplement manufacturers have a free run outside the purview of FDA. They must comply with food product manufacturing guidelines. Supplements are just that – a group of foods formulated to supplement the normal diet. They are not medicine or a replacement for a balanced diet. It is important to take any such product only after consulting the doctor because excess intake of a particular vitamin or mineral can be counterproductive for some people who already have those ingredients in sufficient amounts in their body.