Narrator: This is Science Today. Consumers should be wary of dietary supplements marketed for weight loss or enhancing athletic performance. Toxicologist Christine Haller of the University of California, San Francisco, says these products often contain a variety of stimulants which may cause several adverse reactions.
Haller: The products we're real worried about contains ma huang, which is an herbal form of ephedrine and caffeine in combination. And these two products in combination seem to be potentially more dangerous. What people may experience is a sense of nervousness or jitteryness, nausea and vomiting. But it could be more serious - chest pain indicate a possibility of having a heart attack or stroke.
Narrator: Because these are herbal products, they're not regulated by the FDA, so it's up to the consumer to adopt a "buyer beware" attitude.
Haller: These products in general are called thermogenic, but that's just a phrase to look for when you're looking at a label. If they claim it's a thermogenic product, then you really should turn it over and look at the ingredients and by very careful about taking it.
Narrator: For Science Today, I'm Larissa Branin.