U.S. Moves to Seize Dietary Supplement From GNC Warehouses Federal prosecutors have asked judges in two states to authorize the seizure of more than 3,200 cases of controversial workout products from warehouses operated by GNC, the nation's largest specialty retailer of dietary supplements. With names like Jack3d and OxyElitePro, the workout products contain a stimulant called dimethylamylamine, or DMAA for short. In April, the Food and Drug Administration warned consumers that DMAA was an illegal dietary ingredient and that products containing the stimulant could elevate blood pressure, potentially leading to heart attacks. After the agency's warning, USPlabs, the maker of Jack3d and OxyElite Pro, said the company for business reasons had decided to stop making DMAA products. Some leading retailers withdrew their remaining stocks of DMAA products from store shelves, but GNC continued to sell its inventory. Greg Miller, a spokesman for GNC, said in an e-mail on Friday that the company believed DMAA to be a "safe, legal dietary ingredient." But in a challenge to GNC, the Justice Department, acting at the behest of the F.D.A., requested court-ordered seizures this week of both Jack3d and OxyElitePro from GNC warehouses in Leetsdale, Pa., and Anderson, S.C. According to a complaint filed in Federal District Court in Pittsburgh, the F.D.A. conducted an inspection of the GNC warehouse in Leetsdale this month and collected physical samples, photographed the products and seized shipping records. After the inspection, F.D.A. officials notified GNC that the products were adulterated and being illegally held by the company. On June 11, the F.D.A. ordered GNC to detain the products. Federal prosecutors filed a similar complaint on Tuesday in Federal District Court in Anderson, S.C., seeking a seizure of the same products at a GNC facility there. Because the dietary supplement industry tends to voluntarily heed F.D.A. public advisories, the agency rarely feels compelled to take the aggressive tack of seizing products. Shelly L. Burgess, an F.D.A. spokeswoman, said the agency would not comment. Mr. Miller, the GNC spokesman, said the company would not distribute the products at its Leetsdale warehouse until the issue with the F.D.A. had been resolved. But, he said, "GNC will continue to sell through its remaining inventory of the products in its stores." Mr. Miller added that it was unclear to the company why the F.D.A. had initiated the seizure request, given that DMAA-containing products were no longer being made and that distributors other than GNC also had inventories of the products. "Given this situation," Mr. Miller wrote in his e-mail, "it is hard to view this action as anything other than a biased agency action against GNC in retaliation for GNC's stance on DMAA." Since early 2008, the F.D.A. has received reports of at least 86 health problems, including at least five deaths, in consumers who used DMAA products. Although such reports do not prove that the stimulant directly caused health problems, agency officials have warned people not to consume the ingredient.