ABSTRACT: Its been a busy month for supplements. Ray Lewis gets caught using Deer Antler spray. New York Yankees catcher Francisco Cervelli claims that alleged PEDs he purchased from a Miami clinic were “legal ways to aid rehab and recovery.” And the death of a 30-year-old woman who ran the London Marathon is linked to DMAA, a legal-for-sale supplement found in many energy drinks.

Despite the risks to career and health, the U.S. supplement industry is a $28 billion a year operation—and growing. We trust our supplements. They’re all-natural, chemical-free, pure, and clean. Even if they don’t work, they can’t hurt, we say. After all, they’re on the store shelves. So we take creatine before we lift, fuel with carbohydrate drinks on the bike and run, and pound down protein to recover. But do they make a difference? And most importantly: Can they harm us?

HYPOTHESIS: Sports supplements are unnecessary at best and lethal at worst.

METHODS: Enter DMAA, a drug originally developed by Eli Lilly to have the same effects as amphetamines without their addictive properties, says Pieter Cohen, M.D., an assistant professor of medicine at Harvard University with a special interest in supplements. Over the last seven years, DMAA has wound up on to the World Anti-Doping Agency’s list of prohibited substances and has been banned by the U.S. Defense Department and a host of European countries. It’s also in your energy drinks—Jack3d (until recently) and OxyELITE Pro being two of the more prominent brands—and appeares in 250 commercial products, according to a 2013 study in in JAMA Internal Medicine.

The question: Is it natural and is it safe? 

RESULTS: It’s neither safe nor “natural.” While studies funded by supplement maker USPlabs found DMAA in the plant geranium, two follow-up studies—one in the Journal of Analytical Toxicology and the other by the University of Texas—found that DMAA does not exist in nature in the same structure as it does in supplements.

DISCUSSION: There’s a low bar for safety and efficacy when it comes to your supplements. And it all goes back to the Dietary Supplement Health and Education Act of 1994 (DSHEA), Cohen says. In the early ‘80s and ‘90s, people were making outrageous claims—vitamin C can cure cancer, etc. But the Food and Drug Administration (FDA) spotted a problem: At high doses, many vitamins are dangerous. So the agency logically moved to “set limits on how much vitamins could be found in pills,” Cohen says. The backlash was fierce. People feared that the “FDA was making this power move to turn supplements into prescriptions drugs,” and the drive to regulate vitamins was crushed.

Meanwhile, herbal ingredients, amino acids, and probiotics were thrown into the same regulatory mix as vitamins and minerals. Under the new laws, manufactures could make wild claims—last 10 times longer in bed, run at the speed of Usain Bolt—without repercussion. The only bar they had to pass: New ingredients had to “give some very minor amount of safety data to the FDA,” and anything sold as a supplement or found in food before the bill’s passing were grandfathered in as legal, Cohen says.