Buyer Beware

Measure for Measure: The FDA finds that many supplements designed for weight loss contain dangerous levels of prescription meds  Mark Andersen/Getty Images

How do prescription drugs make their way into supposedly "natural" supplements? It probably goes back to the source. Some 60 to 80 percent of the active ingredients for pharmaceuticals are manufactured in China and India, where manufacturing regulations are more lax, estimates Darrell Abernethy, the chief science officer for U.S. Pharmacopeia, the organization that sets scientific standards for pharmaceuticals for the FDA. "If someone snuck sibutramine to scientists in one of China's [illegal] cottage laboratories, they could reverse-engineer it in a week," he says.

Levy suspects that manufacturers overseas spike diet supplements with synthesized drugs and ship them to the U.S. in orders too small to police. American distributors of two products on the FDA's list — Applied Lifescience Research Industries' Venom Hyperdrive 3.0 (sibutramine) and Nikki Haskell's StarCaps (bumetanide, a diuretic) — blame tainted ingredients from abroad. But, Levy says, "I think much of it is willful blindness."

Making matters murkier, the FDA doesn't screen supplements for safety pre-market — let alone effectiveness — so products guaranteeing weight loss of 50 pounds in two weeks go unpoliced until they hurt someone. That could soon change, though, after a March report from the federal Government Accountability Office suggested that Congress give the FDA more authority to regulate supplements and require makers to disclose full ingredient lists and all reported side effects.

For now, determining exactly who's spiking the pills is near impossible. And whoever the culprits, demand for the supplements won't stop. If someone loses weight because he is unknowingly taking a drug, he will keep buying the product. If he quits, he'll gain it all back — the hard truth of even prescription medication.

"There is, sadly, a business model," says Marc Ullman, a food-and-drug lawyer in New York who is handling StarCaps' recall (and insists that his client was duped by suppliers). "A company will make insane claims, put a pharm ingredient in their product, and shut down and start another business if they get caught. What's the worst thing that will happen?" he asks rhetorically. "A warning letter from the FDA?"