They often don’t contain what’s on the label. No surprise in this unregulated industry:

“We’ve known about this problem for a long time,” said Dr. Wallace Sampson, editor of The Scientific Review of Alternative Medicine and a clinical professor of medicine at the Stanford University School of Medicine. “Dosing in these products can vary from 0 percent to 300 percent.”

Lack of monitoring is the big problem, said Dr. Joan Von Feldt, an associate professor of medicine at the University of Pennsylvania in Philadelphia.

“These nutraceuticals aren’t monitored or regulated in the same way as prescription drugs are,” said Von Feldt, an arthritis specialist. “And this issue has been identified with a lot of these products. And it’s not just a problem with the dose of the therapeutic agent, but also with the possibility of contaminants.”