F.D.A. Issues Warning on Workout Supplement

Certain workout-booster and fat-burning products, sold in recent years by retailers like GNC and Vitamin Shoppe, are illegal and may present serious health hazards to consumers, federal health regulators have determined.

With names like Jack3d and OxyElite Pro, the popular products contain a stimulant known as dimethylamylamine, or DMAA for short. In a public warning late Thursday, the Food and Drug Administration said that the stimulant did not qualify as a legal dietary supplement ingredient and that it could raise blood pressure, potentially causing heart attacks and other health problems.

Since early 2008, the agency has received reports of 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 the health problems, agency officials warned people not to consume the ingredient.

“We are very concerned,” Daniel Fabricant, the director of F.D.A.’s division of dietary supplements programs, said in a phone interview Friday. “We think consumers should stay away from products containing DMAA.”

Steve Mister, president of the Council for Responsible Nutrition, a trade group, said on Friday that the dietary supplement industry should honor the agency’s warning.

“The F.D.A. has spoken,” Mr. Mister said. “We are urging the industry not to manufacture products with DMAA. Retailers should heed the advisory as well.”

A lawyer for USPlabs, the Dallas company that markets Jack3d and OxyElite Pro, said his client disagreed with the F.D.A.’s position.

“USPlabs continues to believe that DMAA is legal, or otherwise they would not be selling it,” said the lawyer, Peter B. Hutt of Covington & Burling in Washington.

As of Friday afternoon, GNC was still selling Jack3d (pronounced “Jacked”) on its Web site as a “hot buy.” A company spokesman did not return requests for comment.

Vitamin Shoppe appears no longer to be stocking Jack3d, and now offers only Jack3d Micro, a newly formulated product that does not contain DMAA.

The F.D.A. warning comes as the agency faces mounting pressure from medical researchers, sports organizations and investigations in the news media to take action on the stimulant.

In late 2011, the Defense Department pulled products containing DMAA from stores on military bases, pending an investigation into the deaths of two soldiers who died after they used the stimulant. Last month, an article in The New York Times described the death of one of those soldiers, Michael Sparling, who collapsed during a training run with his unit in 2011 after taking Jack3d and died soon after. The Sparling family has filed a lawsuit against GNC, where he bought the product, and USPlabs.

On Friday night, the NBC News program “Rock Center With Brian Williams” was scheduled to broadcast a segment on Mr. Sparling and DMAA products.

Mr. Hutt, the USPlabs lawyer, said the F.D.A. made its announcement to get out in front of the NBC report and shield itself from being criticized for lax enforcement.

“This is the agency’s customary attempt to protect itself,” Mr. Hutt said. “These reports rely on a plaintiff’s unsubstantiated allegations. There is no evidence that the soldier’s death was caused by DMAA.”

Although health regulators in at least seven countries, including Canada, have effectively banned supplements containing DMAA, the products have remained widely available at supplement stores in the United States. Some medical researchers say federal health regulators should have warned American consumers much earlier.

“We’ve had hundreds of millions of dollars spent on products that should have never been on the marketplace to begin with,” says Dr. Pieter Cohen, an assistant professor at Harvard Medical School who studies dietary supplements. “There’s no reason the F.D.A. should have waited to warn the public of the dangers of consuming the ingredient.”

A year ago, the F.D.A. issued letters to 10 companies that marketed DMAA products, saying the stimulant did not fit the legal definition of a supplement as a vitamin, mineral, herbal or botanical ingredient used to supplement the diet. The stimulant was originally developed in the 1940s by Eli Lilly, the pharmaceutical company, as a nasal decongestant called Forthane, but the drug maker officially withdrew the medicine from the market in the 1980s.

Among the companies that received the federal warning letters last year, all but USPlabs agreed to stop marketing DMAA products, according to the F.D.A. advisory. USPlabs submitted published studies on the ingredient in an effort to challenge the F.D.A.’s position, the advisory said, but the agency found the information “insufficient to defend the use of DMAA as an ingredient in dietary supplements.”

Mr. Fabricant said the F.D.A. intended to take further steps to remove the stimulant from the market. Although he declined to comment specifically on USPlabs, the agency’s options in such cases generally include asking a supplement maker for a voluntary recall of potentially hazardous products, seizing such products or instituting a mandatory recall.

“We are going to use all of the tools available to us to get this out of distribution,” Mr. Fabricant said.