Vitamins & supplements.

The article looks at nutritional supplements. It reports that many Americans take vitamins, herbs, or other nutritional supplements. It says that they can pose dangers to health that are not widely understood, and discusses several kinds of hazards. It reports that some supplements have been found to contain prescription-drug ingredients which are not disclosed on the product labels. It says that vitamins and minerals that are normally safe can be dangerous if taken in large quantities. It notes that unlike drugs, the manufacture of supplements is not regulated by the U.S. Food and Drug Administration, and impurities and other quality problems have been reported.