Recent studies indicate that numerous prenatal vitamins fall short in essential nutrients necessary for a healthy pregnancy, while some also contain harmful quantities of toxic metals.
A study featured in The American Journal of Clinical Nutrition assessed the levels of choline and iodine in both nonprescription and prescription prenatal vitamins, along with an examination for toxic metals such as arsenic, lead, and cadmium.
“Many women depend on prenatal vitamins and minerals during pregnancy to enhance their health and support their baby’s growth. Choline and iodine are among the key nutrients needed for fetal development. However, some prenatal vitamins might not provide the amounts specified on their labels, and some may not include any choline or iodine at all,” stated Laura Borgelt, PharmD, MBA, the study’s lead author and a professor at the University of Colorado Skaggs School of Pharmacy and Pharmaceutical Sciences at CU Anschutz. “This research aims to empower women with knowledge about the nutrient content in prenatal supplements, enabling them to make more informed choices and select the optimal options for their health and their babies’ welfare.”
The research team evaluated 47 prenatal vitamins (comprising 32 nonprescription and 15 prescription varieties) purchased from online and local retailers frequented by consumers. They compared the actual levels of choline and iodine in their laboratory assessments with the amounts stated on the labels and also screened for arsenic, lead, and cadmium, aligning their results with established safety standards that allow a deviation of up to 20% from the claimed values.
The Food and Nutrition Board of the Institute of Medicine recommends a daily intake of 450 mg of choline during pregnancy, which increases to 550 mg per day while breastfeeding, with a maximum limit set at 3,500 mg per day. For iodine, the dietary reference intake for women aged 19 and older is 150 mcg per day; during pregnancy, this increases to 220 mcg daily, and to 290 mcg daily during lactation. The upper tolerance limit for iodine is set at 1,100 mcg per day.
Moreover, the United States Pharmacopeia has established purity standards for pharmaceuticals that include maximum permissible levels for harmful substances: 2.5 mcg of arsenic per oral daily dose, 0.5 mcg of cadmium per oral daily dose, and 0.5 mcg of lead per oral daily dose.
The results revealed that most prenatal vitamins do not disclose choline content, and many that do fail to meet the claimed amount. Only 12 out of the tested sample noted their choline content — roughly 26% — and just five of those (42%) contained the advertised levels of choline.
When examining iodine, it was found that most prenatal vitamins provided less than advertised, with only 53% listing iodine content, and a mere four products (16%) contained the correct amount of iodine as indicated on their labels.
The study also uncovered that some prenatal vitamins had higher than expected levels of heavy metals. Specifically, seven products exceeded the limits for arsenic, two had excessive lead, and 13 exceeded the cadmium limits stated by the U.S. Pharmacopeia. Exposure to these metals during pregnancy has been linked to negative birth outcomes.
“This study represents one of the first comprehensive assessments of actual choline and iodine content across a wide range of prenatal supplements. The detection of contaminants, particularly cadmium, raises serious concerns. Our findings emphasize the significant disparity between label claims and actual product contents, highlighting a critical need for enhanced regulatory oversight in this sector,” Borgelt remarked.
The authors pointed out that while there is a pressing need for more stringent regulations to ensure the adequacy of supplements, it is crucial for pregnant women to continue taking prenatal supplements. They recommend verifying the ingredient contents or consulting with a healthcare professional to select the appropriate prenatal vitamin.
This research received funding from the Center for Science in the Public Interest through a grant from the John Sperling Foundation.
