TUESDAY, Aug. 26 (HealthDay News) -- About one in five ayurvedic medicine products purchased on the Internet contain significant levels of lead, mercury or arsenic, a new study finds.

The researchers found that products manufactured in the United States were even more likely to contain the metals than those made in India, where the ayurvedic approach was first developed centuries ago. Furthermore, 75 percent of the products containing lead, mercury or arsenic advertised that they were manufactured using "Good Manufacturing Practices," which is a U.S. Food and Drug Administration (FDA) regulation meant to ensure quality.

"We randomly purchased 193 traditional Indian (ayurvedic) medicine products from the Internet. About 60 percent were from U.S. companies and 40 percent from Indian companies. Twenty-one percent had significant levels of lead, mercury and arsenic," said the study's lead author, Dr. Robert B. Saper, an assistant professor of family medicine at Boston University School of Medicine, and director of integrative medicine at Boston Medical Center.

In high levels, these metals can be toxic.

Results of the study are published in the Aug. 27 issue of the Journal of the American Medical Association.

Ayurvedic medicine is an ancient Indian practice that combines the use of numerous modalities, such as herbal medicine, massage and special diets, to promote wellness and prevent illness, according to the U.S. National Center for Complementary and Alternative Medicine.

There are two common practices in ayurveda -- either herbal medicine alone, or herbal medicines combined with metals and gems, a practice known as rasa shastra. In rasa shastra, herbs are combined with metals such as lead, mercury, iron and zinc, and gems such as pearl. Those that practice this type of ayurveda believe it is safe and therapeutic, according to the study.

Saper said that "many traditional Indian practitioners believe quite strongly that if rasa shastra is done correctly, it is safe," that he feels these practices should be "seriously called into question." Saper also said that he doesn't believe anyone should deliberately ingest lead, mercury or arsenic.

The current study included 193 products randomly selected and purchased over the Internet. The researchers found that 20.7 percent contained metals. The rate in U.S. manufactured products was 21.7 percent, and in Indian products, it was 19.5 percent.

Not surprisingly, almost 41 percent of rasa shastra products had a greater prevalence of metals, including high levels of lead and mercury. "Several Indian-manufactured rasa shastra medicines could result in lead and/or mercury ingestions 100 to 10,000 times greater than acceptable limits," the researchers wrote.

Seventy-five percent of the products claimed to be manufactured under Good Manufacturing Practices.

Products made by members of the American Herbal Products Association (AHPA) were less likely to contain metals, according to the study.

Michael McGuffin, president of the AHPA, said, "It's not an accident that AHPA members performed better. We've called our members attention to the presence of heavy metals in plant materials. Lead is ubiquitous. It's in the soil and in the plants. I don't think you can get these levels to zero, but it is the manufacturers' responsibility to know the amount and to limit it."

AHPA also recommends that its members don't manufacture rasa shastra products.

Saper said that the FDA hasn't currently set a maximum level allowed for lead, mercury and arsenic in dietary supplements, but he believes they should.

McGuffin recommended buying products made by members of AHPA, because the study found they were least likely to contain metals, and he said consumers should call the makers of their medicines and "ask tough questions." He said if you call a company and ask what their limits are for lead, and the representative says they don't know, that's a red flag.

More information

Learn more about ayurvedic medicine from the National Center for Complementary and Alternative Medicine.