In a move designed to halt sales of popular workout stimulants, the U.S. Food and Drug Administration (FDA) recently issued warning letters to some 14 dietary supplement companies. At issue is an unapproved ingredient known as AMP Citrate, also known as DMBA. The letters take the companies to task for failing to comply with the notification provision of the Dietary Supplement Health and Education Act of 1994, which requires companies to provide the FDA with advance notice before sales of products with “new dietary ingredients.” Companies refusing to “immediately cease distribution” of products containing AMP Citrate face injunctions and seizures.

The FDA letters point out that a dietary supplement containing a new ingredient not marketed before 1994 “shall be deemed adulterated” unless it meets two requirements: (1) the ingredient was present in the food supply as an article used for human food in a form in which the food has not been chemically altered; and (2) a history of use or other evidence establishing the safety of the ingredient when used as suggested on the label. Even if the companies had provided such information, however, the FDA considers the products likely to be adulterated and unsafe because the agency has no evidence supporting the safety of Amp Citrate, which it considers to be synthetic.

On Sept. 12,2014, the Council for Responsible Nutrition (CRN), a dietary supplement industry group, sent a letter to the FDA expressing its concern about the potential dangers to consumers who may be using possible unsafe supplements containing Amp Citrate” and requesting regulatory action. CRN noted that Amp Citrate was being marketed as an alternative to a previously banned ingredient, known as DMAA, and that it had a similar chemical structure to DMAA. CRN also pointed out that none of those selling the supplements filed required “new dietary ingredient” paperwork with the agency to substantiate Amp Citrate’s safety.

The dietary supplement industry is lightly regulated by the FDA. Dietary supplement manufacturers and distributors are not required to obtain approval from FDA before marketing supplements, because the FDA does not consider them to be drugs. Rather, dietary supplements are defined as a kind of food; thus, unlike drugs, supplements are not subject to the same rigorous evaluation process for safety and effectiveness as prescription drugs. These recent enforcement activities, however, signal an increased level of scrutiny, so it remains to be seen whether or to what extent the FDA will continue to flex its muscles in this arena.