When Leanne Sparling took the call on June 1, 2011, the voice on the phone told her to pray. It was all she could do to save her son’s life.

That morning, Michael Sparling collapsed during a run with his Army unit at Fort Bliss, Texas, went into cardiac arrest, and was rushed to the hospital. When the commander of the hospital called Leanne, Michael was receiving CPR, but ultimately the doctors failed to resuscitate him. Before noon, he was gone, dead of a heart attack at age 22.

Sparling was shocked, grief-stricken, and confused: Her son had a heart attack? He was fit and active. He played soccer and football during junior high in California, took martial arts lessons with his father, and went snowboarding. But at 145 pounds and standing just under six feet, Michael thought himself small for an infantryman. During basic training at Fort Benning in Georgia, a friend recommended Jack3d, a performance-enhancing supplement from USP Labs. The Dallas-based distributor sold its workout and fat-burning dietary supplements directly to consumers as well as to large retailers like GNC. Roughly four weeks prior to leaving Fort Benning for Fort Bliss, Michael purchased a container of Jack3d powder.

Its name was a play on “jacked,” slang for describing anyone whose muscles call to mind the Hulk’s biceps. Yet its key ingredient, methylhexanamine, was suspect. More commonly known as DMAA, it’s an amphetamine-like stimulant that narrows blood vessels and arteries, causing blood pressure to rise, which in turn gives users a boost of energy. Shortness of breath and a tightening in the chest can also follow.

Such dangers usually don’t slow buyers. Americans spend almost $37 billion on dietary supplements each year, including one-third on products that claim to bulk bodies up or slim them down. And emerging research suggests that many young men may be particularly susceptible to such claims targeting body image insecurities, with new studies reporting teenage boys’ preoccupation with gaining muscle and dropping weight. At the same time, some 23,000 Americans go to the emergency room annually because of dietary supplements.

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