Tests Show Many Supplements Have Quality Problems

But his group only represents 250 of the 1,500 companies selling such products. And even though millions of people take supplements with no apparent ill effects, there have been many quality problems that a consumer might never realize because they don't always produce symptoms:

Contaminants
ConsumerLab.com found lead in at least one brand each of zinc, black cohosh and ginkgo products tested in recent years. Lead can accumulate and cause many health problems, and the testing company wants a national limit of 0.5 micrograms per day -- a level that in California requires a warning on the label.

A fungal toxin was found in four red yeast rice products in March 2008. And in 2007, federal officials warned about a liquid herbal supplement sold for colic and teething pain after finding cryptosporidium, a waterborne parasite that causes severe diarrhea.

Ayurvedics -- popular herbals used in traditional medicines from India -- often contain hazardous metals, studies in medical journals report. In 2004, researchers tested 70 ayurvedic remedies in the Boston area and found that one in five had potentially harmful levels of lead, mercury or arsenic. Tests in Houston, Chicago, San Francisco and New York City turned up similar results.

Metals naturally accumulate in certain herbs and come from the soil they are grown in. Many supplement ingredients come from Europe, India and China.

"We don't know how much of the ingredients are imported -- whether they're coming from across town or across the world," Mister of the trade association conceded.

But even manufacturers get duped, said Jana Hildreth of the Analytical Research Collective, a group of scientists advocating better supplement testing.

"Companies started going to China and demanding lower prices," and unscrupulous suppliers sometimes spiked products with cheap ingredients that can trick lab tests, she said. An example: a buckwheat derivative, rutin, in place of pricier ginkgo.

Potency Problems
In ConsumerLab.com testing last November, four out of seven supplements contained less ginkgo than claimed on their labels, and one failed to break apart properly to release its ingredients. Seven out of nine failed in tests in 2003, as did six out of 13 in 2005.

"It is now believed that ginkgo is among the most adulterated herbs," the company reports.

Tests by California scientists of two dozen ginseng supplements, reported in a nutrition journal in 2001, found that many differed from their labels. The concentrations of some ginseng compounds varied by up to 200-fold from product to product.