Updated

The deaths of two U.S. soldiers who collapsed during physical training in the last few months have prompted a military investigation of a popular body-building supplement that was found in their systems.

The dietary supplement Dimethylamylamine, or DMAA, has been banned for sale at stores and commissaries in military bases across the country pending the results of the probe.

DMAA is derived from geranium oil and is classified by the Food and Drug Administration as a food additive. The supplement acts as a stimulant, giving users that extra boost of energy during a workout or training. Many soldiers use it to meet the strong physical demands of their training and service.

“There’s an incredible amount of pressure to perform well, especially after a reduction of forces,” said retired Army Brig. Gen. Rebecca "Becky" Halstead, who now runs a company that specializes in leadership training. “Our safety record is pretty good, but we need to do more with proper nutrition and opportunity for rest. Some might say that it could add to the military’s cost, but what is the cost of not doing it?”

In one incident last summer, a 22-year-old soldier collapsed and died during a training run at a Southwestern U.S. military base. In the other, a 32-year-old collapsed during a fitness test the following fall, and died after a month in the hospital. Autopsies on both revealed the presence of DMAA in their systems.

The Department of Defense has assembled a number of reports of other adverse effects among potential and known DMAA users, including kidney and liver failure, seizures, loss of consciousness, heat injury and muscle breakdown, and a rapid heartbeat, according to a spokesman.

While the FDA considers DMAA to be a safe food additive, its Canadian counterpart, Health Canada, has reclassified it as a drug that requires authorization to be sold legally.

A spokeswoman for the FDA declined to comment about DMAA directly but said, “With any complaint or concern we receive about FDA-regulated products, we will consider whether a violation of the federal food, drug, and cosmetic act has occurred and, if so, whether regulatory action is warranted.”

But many supplement companies in the U.S., anticipating that a ban is on its way, have voluntarily stopped including DMAA in their products.

“Our biggest issue is not one of safety, but of regulation. Our expectation is that DMAA will eventually be banned,” said James Klein, CEO of the supplement company Ergogenix, which stopped using DMAA in their ErgoPump and ErgoBurn products this past June. “We have found a better solution, so we tried to get ahead of the curve.”

He said Ergogenix has replaced DMAA with N-Methyltyramine, which he claims produces the same results with less potential for danger.

Klein added, however, that his company found DMAA to be perfectly safe in “sensible doses.”

While the Defense Department has placed a moratorium on sales of DMAA products on all bases pending the results of its investigation, products containing the supplement remain on sale at national retailers like GNC and The Vitamin Shoppe.

“We feel that the outcome of the military’s safety review is that it [DMAA] is a safe product,” said Kerri Toloczko, a spokeswoman for USP Labs, the makers of JACK3D, the top-selling DMAA-based product. She said JACK3D is very popular among soldiers and is the No. 1 supplement sold at GNC stores on Army bases.

“USP stands firmly behind DMAA. It has an excellent safety record,” Toloczko said. “440 million servings of DMAA have been used by consumers since 2007 without any issue. If you have 440 million servings of anything, you would expect to see some issues, which we haven’t.”