Study finds lead in over-the-counter dietary supplements
researcher warns supplements could contain lead at levels unsafe for pregnant women, children

Currently, over-the-counter dietary supplements, such as ginko biloba and St. John’s wort, are not subjected to Food and Drug Administration (FDA) approval. Therefore, many scientists have tested the supplements to determine their effectiveness and safety. In a study that included more than 86 dietary supplement products purchased in 2000 and 2001, a University of Missouri-Columbia researcher has found that some of the products contain lead at levels that are dangerous to children and pregnant women.

"There are two ways that lead and other potentially toxic trace metals may be seeping into the supplements," said Dave Robertson, a professor of Chemistry and researcher at the MU Research Reactor. "Plants may draw and accumulate heavy metals from the ground as they grow. In addition, there is the possibility of metal contamination being introduced along with the binders or during the manufacturing process of these products."

Robertson oversaw the research that was conducted by Ethan Balkin, a senior biology major at MU. Using a technique called x-ray fluorescence, the team tested more than 20 types of dietary supplements in 86 products. The researchers ground several samples of each product into powder, shaped it into a large pellet and subjected it to x-rays. During this process, the elements emitted a distinct spectroscopic signature, which is a unique method of x-ray identification. By identifying and measuring the signature the researchers were able to determine what elements were present and in what quantity.

The researchers scanned for 72 elements, including lead, nickel, copper and arsenic. Lead was the only element that exceeded the federal safety standard for consumption. In the products they tested, 58 contained levels of lead that exceeded safety standards for children under 6 years old, 39 exceeded safety standards for children age 7 or older, and 18 supplements contained lead levels that exceeded safety standards for pregnant women. However, more recent tests of the same products purchased in 2003 indicate that the quality of the supplements may be improving.

"There is clearly the potential for toxic materials to slip in to these supplements and we should make sure that there is good quality control in the manufacture of these materials," Robertson said. "However, preliminary results from our most recent survey indicate less lead contamination than we observed in our original study."

The study was funded in part by the National Science Foundation and was presented at the 2002 summer conference of the Federation of American Societies for Experimental Biology.

2002

Additional links:

Robertson Lab
Department of Chemistry
MU Research Reactor

Division of Biological Sciences

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