Hitting the limits

Last reviewed: July 2010

For most drinks we tested, levels of those contaminants were in the low to moderate range, when we could detect them at all. But with three of the products, consumers who have three servings daily could be exposed to levels that exceed the maximum limits for one or two of those contaminants in dietary supplements proposed by U.S. Pharmacopeia (USP), the federally recognized authority that sets voluntary standards for health products. Nutritionists and trainers say they commonly see people who consume three servings a day.

The amount of lead in a single daily serving of eight of the protein supplements we tested would require that the products carry a warning in California. State legislation known as Proposition 65 mandates that manufacturers notify consumers when products contain toxic substances at levels the state says pose even a low cancer or reproductive risk.

But federal regulations do not generally require that protein drinks and other dietary supplements be tested before they are sold to ensure that they are safe, effective, and free of contaminants, as the rules require of prescription drugs.

"Most consumers and even many doctors don't realize that in this country we're left to simply trust the manufacturer to decide what level of quality and safety they'll provide," says Pieter Cohen, an internist at Cambridge Health Alliance and author of a recent New England Journal of Medicine article on contaminants in dietary supplements. Even in California, some manufacturers don't comply with the requirements of Proposition 65 to put warnings on supplements, and enforcement seems to be lax. Sometimes warnings appear only after lawsuits are filed.