American researchers went online to order Ayurvedic medicines, and discovered lead, mercury or arsenic levels that exceed acceptable standards in their purchases, according to a study published Tuesday.

Authors of the study, published in the Journal of the American Medical Association, wrote that "since 1978, more than 80 cases of lead poisoning associated with Ayurvedic medicine use have been reported worldwide."

Ayurveda is an ancient Indian medical practice. The majority of the country's population uses Ayurvedic medicines, which are divided into two main types: herbal-only and rasa shastra. Rasa shastra combines herbs with metals, minerals and gems, such as mercury, lead, iron, zinc, mica and pearl.

Dr. Robert B. Saper of the Boston University School of Medicine and colleagues conducted a study to compare the prevalence of toxic metals Ayurvedic products produced in the U.S. and India. Ninety-five percent of those products containing metal were produced in the U.S.

Using the search terms "Ayurveda" and "Ayurvedic medicine," researchers did an Internet search and found 673 products. Of those, they randomly bought 230.

They measured metal concentrations using x-ray fluorescence spectroscopy and found that rasa-shastra medicines were more than twice as likely to contain detectable metals, than natural products. They also had higher median concentrations 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," Saper and colleagues wrote.

Researchers are looking for stricter guidelines from the U.S. Food and Drug Administration.

Health Canada has issued several advisories for Ayurvedic medicines, warning that unapproved products may contain high levels of heavy metals.

"Consumers should exercise caution when purchasing health products from outside Canada or over the Internet, as these products may not have undergone the same degree of assessment as those authorized for sale in Canada," read the latest advisory released in May 2008.

Companies have to apply to Health Canada and prove their product is safe, effective and of high quality before they are issued a drug identification number (DIN) or natural product number (NPN), said a spokesperson for the department.

Uses of Ayurveda: then and now

Ayurveda is an ancient Indian medial system that has been practised for more than 5000 years. Along with the use of herbs, minerals and metals it includes therapy relating to physical, mental, social and spiritual harmony. Yoga is linked closely to the practice.

Ayurvedic medicinal products range from tablets and jams to oils and creams, which can be used for a variety of ailments including menopause and certain cancers. Indian asparagus, for example, balances estrogen and progesterone levels, while triphala, a combination of berries, is used to fight pancreatic cancer, practitioners say.

Ismat Nathani, of the Centre for Ayurveda and Indian Systems of Healing, an educational and wellness centre based in Toronto, says the best option for Canadians is to buy products approved by Health Canada/.

She says many consumers turn to the U.S. websites because of a wider selection of products.

"A lot of desperate consumers are looking for other options,' Nathani said. 'Canadian consumers mainly shop in the U.S."

Nathani said while the herbal forms can be "amazing remedies" for issues such as digestive problems, the traditional rasa shastra practice using metals is not relevant to today's Western society.

"People think it's a general practice but it's not. It's not meant for everyone to be taking it," she said.

One of the meanings of rasa is "to build the body fluids" and is a form of rejuvenation, she said. But the practice was used mainly in the 18th century.

"In the past centuries there was a depletion of metals in human bodies but in today's post-modern society we are actually overloaded with metals," she said.

Rasa shastra was used as a last resort for mass epidemics like cholera and typhoid, she said.

"It's not necessarily that kind of practice needed at this time."

Those who are still looking for specialized rasa shastra practitioners may have trouble finding them outside of India, she said.