An investigation revealed hundreds of dietary supplements found by government regulators are tainted with hidden ingredients that could cause serious health risks.
Dr. Daniel Fabricant oversees dietary supplements for the U.S. Food and Drug Administration and warns consumers to discuss supplements with their doctor before using them.
"We've warned consumers in certain areas of products," said Fabricant.
"There are tainted products that are sparked with illegal drugs and we've certainly been vigilant about trying to message that to consumers."
A database of tainted supplements with data supplied by the FDA that reveals nearly 500 tainted supplements since 2007. You can search the database at the bottom of this story.
The FDA says there are more than 85,000 dietary supplements on the market.
Even so, the FDA says "it does not approve products for safety or efficacy prior to them going to market."
Fabricant believes part of the problem lies in consumer expectations.
"Consumers may look at a dietary supplement, they may look at a pill form, tablet form, capsule form and they think, okay, this is like the medication I get from my doctor with a prescription and the FDA has signed off on it — and that's not the case."
A Cleveland woman suffered severe liver damage after taking one dietary supplement for months.
Phetsamone Senevoravong, 33, said she using OxyElite Pro for months to help her lose weight.
"My liver's damaged," said Senevoravong, "the second main organ in your body — so I'm scared."
Following actions by the FDA last October, the Texas-based company agreed to recall and destroy the supplement that has been linked to 56 cases of acute liver failure and hepatitis.
The FDA sent a letter to the manufacturer to "immediately cease distribution" and the investigation continues into what may be responsible for the illnesses.
Dr. Stanley Cohen is a liver specialist and said Senevoravong "had pretty advanced liver disease."
Cohen also warned consumers to be wary of claims often associated with dietary supplements.
"One of the biggest things we see is that consumers think 'natural' means safe," said Cohen.
"Natural just means it comes from the earth and we don' t know much about it and that's the problem."
And the FDA said that, just last year alone, it received 2,300 complaints of "adverse events" from manufacturers and another 1,000 from consumers who have taken dietary supplements.
Even so, the leading association representing the supplement industry insists the vast majority of dietary supplements are safe.
Steve Mister is CEO of the Council for Responsible Nutrition, which published its own guidelines for consumer safety.
"Any health concern is a very serious one for the consumers involved and that should be taken seriously," said Mister.
"But we also think that given the millions and millions of consumers every day that use dietary supplements that the kind of problems that have been highlighted really represent just a very small fringe of the industry."
Fabricant said consumers should be particularly suspect of claims "to cure disease" or "totally safe."
But the FDA also said that many supplements can be beneficial and "help assure an adequate intake of essential nutrients."