Prenatal vitamins may have dangerous levels of lead and arsenic, according to a new study

Some prenatal vitamins contain “disturbing” amounts of toxic heavy metals, while others lack key nutrients needed for a healthy pregnancy, a shocking new study finds.

Researchers from the University of Colorado Anschutz Medical Campus tested 47 prenatal vitamins – 32 over-the-counter and 15 prescription – for their levels of choline and iodine and checked for arsenic, lead and cadmium.

Seven products had arsenic above purity limits set by the US Pharmacopoeia, two had too much lead and 13 had too much cadmium. Cadmium poisoning can cause chills, fever and muscle aches, and chronic exposure can damage the kidneys, bones and lungs.

“The presence of contaminants, particularly cadmium, was … worrisome,” said Laura Borgelt, first author of the study.

Borgelt’s team also found a gap between what is listed on the labels and what is actually in the products.

The recommended amount of choline – which supports the development of the baby’s brain and spinal cord and helps prevent birth defects – is 450 milligrams per day during pregnancy and 550 mg/day during lactation.

The researchers found that only 12 of the 47 products, about 26%, listed choline, and only five products contained the amount of choline promised on the label.

“During pregnancy, many women rely on prenatal vitamins and minerals to support their health and their baby’s development,” Borgelt said. “Among the most important nutrients for fetal development are choline and iodine.”

Iodine is needed to produce thyroid hormones essential for proper fetal growth and development. The recommended intake of iodine is 220 micrograms per day for pregnant women and 290 mcg/day for nursing mothers.

Of the 25 products that listed their iodine content, only four contained the amount of iodine stated on the label.

The findings were published this week in The American Journal of Clinical Nutrition.

Borgelt proposes “stronger regulatory oversight” of prenatal vitamins, echoing a 2023 federal government report that called for additional U.S. Food and Drug Administration authority to oversee dietary supplements because of discrepancies between what’s on prenatal supplement labels and what’s in the products.

Most prenatal vitamins are available OTC, which means the FDA does not regulate them as strictly as drugs.

Despite these issues, the study authors still recommend taking prenatal vitamins during pregnancy. Consumers should double check the ingredients on the label or work with their healthcare provider to choose the best supplement.