Soldier's parents sue GNC and USPlabs over his death SAN DIEGO, Feb. 15 (UPI) -- The parents of a soldier whose death led to a federal investigation of a workout supplement have sued its developer and the retailer GNC in California. The lawsuit was filed Wednesday in state court in San Diego, The New York Times reported. The parents of Michael Sparling charge the supplement Jack3d -- pronounced Jacked -- should have carried warning labels because one of its ingredients, the stimulant dimethylamylamine, can raise blood pressure and heart rate. The defendants are USPlabs, which developed and markets Jack3d, and GNC, where Sparling allegedly bought the supplement. Jack3d is still marketed by GNC and other chains, the Times said. The Defense Department has banned it from stores on military bases. A report in Military Medicine, the journal of the Society of Federal Health Professionals, said DMAA, combined with ingredients like caffeine, could increase the risk of heart attacks and strokes. The death of Sparling and another soldier led to the federal study. "It's a pharmaceutical-grade product which is being directly introduced into the supplement marketplace with absolutely no regulatory oversight," Dr. Pieter Cohen of Harvard Medical School told the Times.