FDA regulates both finished dietary supplement products and dietary ingredients. FDA regulates dietary supplements under a different set of regulations than those covering “conventional” foods and drug products.
Under the Dietary Supplement Health and Education Act of 1994 (DSHEA):
Manufacturers and distributors of dietary supplements and dietary ingredients are prohibited from marketing products that are adulterated or misbranded. That means that these firms are responsible for evaluating the safety and labeling of their products before marketing to ensure that they meet all the requirements of DSHEA and FDA regulations.
The FDA is responsible for taking action against any adulterated or misbranded dietary supplement product after it reaches the market. The FTC also exercises enforcement discretion in dietary supplement labeling and advertising.