At the end of November, a team of researchers at the University of Colorado Anschutz announced that several prescription and non-prescription prenatal products they tested contained insufficient amounts of choline and iodine, and contained unsafe levels of heavy metals like arsenic, lead, and cadmium, per USP purity standards for pharmaceuticals.

The study, which was funded by Center for Science in the Public Interest, evaluated a panel of 47 products purchased online and from chain pharmacies.

However, after the full study was published in the American Journal of Clinical Nutrition, USP determined that “the limits, as well as the units, were incorrectly applied and the values presented in the first publication of the study were inaccurate.”

The Council for Responsible Nutrition (CRN) expressed “grave concern” over the flawed methodology and misleading claims published in the study.

The authors of the study used testing reference limits that pertain to ingredients, not finished products. They then measured heavy metal limits in micrograms per daily dose, rather than micrograms per gram, the latter of which is the USP reference limit for ingredients.

Had the authors applied the proper USP standards, found in General Chapter 2232 for dietary supplements, they would have seen that the products fell below established safety limits for heavy metals set by USP, CRN stated. According to CRN, the heavy metal content of the supplements in the present study is consistent with the trace amounts seen in a Government Accountability Office (GAO) report on prenatals.

CRN reports that the dissemination of the study and subsequent media coverage has unnecessarily alarmed pregnant women, and claims that the products contained dangerous levels of lead and arsenic are based on a flawed application of USP standards which misrepresent the safety of the prenatal supplements.

“It is particularly unfortunate that it has taken a month since the study was initially released in prepublication form and a press release was issued by the author’s university to get acknowledgment that the inflammatory conclusion was in error. During that time, numerous media have erroneously reported on the study’s conclusions in reliance on misinformation. And countless women have unnecessarily experienced anxiety over the safety of their vitamin regimens during their pregnancies.”

At press time, it appeared that the University of Colorado Anschutz Medical Campus retracted the press release, which was published in November.

CRN also urged the university and the American Journal of Clinical Nutrition to acknowledge the error and make the appropriate corrections to the study paper, but no changes or retractions have been made yet.