Check labels carefully
Herbs and dietary supplements are considered foods—not drugs—by the FDA, so they’re not held to the same standards for safety and effectiveness that prescription drugs and over-the-counter medications are held to.
“What the label says is in the bottle may not really be in the bottle. In fact, levels of active ingredients can vary by up to 100 percent,” warns Richard Nahin, PhD, senior advisor for scientific coordination and outreach at the National Center for Complementary and Alternative Medicine (NCCAM).

In addition, he adds, supplements can sometimes be contaminated with traces of pesticides and heavy metals or even pharmaceutical drugs.

To correct such potentially dangerous possibilities, the FDA’s Office of Nutritional Products, Labeling, and Dietary Supplements has issued guidelines on both quality research and manufacturing. By June 2010, all supplement manufacturers must meet these new requirements.

What can you do in the meantime? First, look for FDA certificied manufacturers, or the Good Manufacturing Practices (GMP) designation on the label, as well as seals from United States Pharmacopoeia (USP), The Public Health and Safety Company (NSF), or Consumer Lab (CL). Also check out Web sites for the FDA, the Federal Trade Commission, and the NCCAM for safety news. You can also subscribe to Consumer Lab, an industry watchdog that tests supplements and then publishes the reports.