Ayurveda, a form of medicine that originated in India more than 2,000 years ago, relies heavily on herbal products. In India, an estimated 80 percent of the population practices Ayurveda, but U.S. Ayurvedic remedies have increased in popularity and are available at South Asian markets, health food stores and on the Internet.

Lead author Dr. Robert Saper, director of Integrative Medicine at Boston University School of Medicine identified 25 Web sites featuring 673 Ayurvedic medicines and randomly selected and purchased 193 products made by 37 different manufacturers.

Overall, 20.7 percent of Ayurvedic medicines contained detectable lead, mercury and/or arsenic. U.S. and Indian manufactured products were equally likely to contain toxic metals. Among products containing metals, 95 percent were sold by U.S. Web sites and 75 percent claimed Good Manufacturing Practices or testing for heavy metals, the researchers said.

The findings are reported in the Journal of the American Medical Association.