Study Shows Choline and Iodine Are Missing Links in Prenatal Supplements

Editor's Note: The study originally published in The American Journal of Clinical Nutrition reported higher levels of heavy metals in prenatal vitamins than allowed by the US Pharmacopeia (USP) standards. However, USP has since clarified that the initial findings were inaccurate due to incorrect application of their limits and units.

Many prenatal vitamins are lacking nutrients like choline and iodine, which are essential for a healthy pregnancy, according to research findings published in The American Journal of Clinical Nutrition.¹

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“During pregnancy, many women rely on prenatal vitamins and minerals to support their health and their baby’s development. Among the most crucial nutrients for fetal development are choline and iodine. However, some prenatal vitamins may not contain the exact amounts listed on the label and some may not contain any choline or iodine,” said the study’s first author Laura Borgelt, PharmD, MBA, professor at the University of Colorado Skaggs School of Pharmacy and Pharmaceutical Sciences at CU Anschutz, in a news release.¹

Prenatal multivitamins and minerals (PMVMs) play a significant role in providing additional supplements to individuals who are pregnant, lactating, or planning pregnancy. The supplements are crucial because 90% of reproductive-aged women have insufficient consumption of 8 major food groups, including vegetables, whole fruit, milk, and whole grains, according to the study authors.²

According to the Food and Nutrition Board of the Institute of Medicine, the recommended intake for choline is 450 mg/day during pregnancy and 550 mg/day during lactation, along with a tolerable upper limit of 3500 mg/day. The recommendation for iodine for women aged 19 and older includes 150 mcg/day, increasing to 220 mcg/day during pregnancy and 290 mcg/day during lactation, with a tolerable upper limit of 1100 mcg/day, according to the news release.¹

The United States Pharmacopeia also released purity standards which limit harmful substances for pharmaceuticals. The standards include 2.5 mcg per oral daily dose for arsenic, 0.5 mcg per oral daily dose for cadmium, and 0.5 mcg per oral daily dose for lead. High exposure to the heavy metals in pregnancy have been linked with adverse birth outcomes.¹

The study authors noted that previously conducted studies have assessed the actual content in PMVNs for key nutrients, including folic acid, iron, and vitamin A, B6, C and E, all of which are essential in supporting a healthy pregnancy. However, research on choline and iodine content is limited.²

Following the increase in consumer reliance on PMVMs, researchers conducted an observational study that assessed the amounts of choline and iodine in nonprescription and prescription prenatal vitamins, along with the presence of toxic metals— including arsenic, lead, and cadmium.^1,2

“Our study aims to help women better understand the nutrient content in prenatal supplements, empowering them to make more informed choices and select the best options for their health and their baby's well-being,” said Borgelt, in a news release.¹

The study tested a sample of 47 different prenatal vitamins, 32 nonprescription and 15 prescription, all purchased from commonly shopped online and local stores. The study authors noted that most PMVMs do not list either nutrient, with only 26% listing choline content and 53% listing iodine content. After comparing the amounts of choline and iodine found in their lab results with the products, the results found that only 42% of products contain the correct amount of choline listed and 16% contain the correct amount of iodine listed.^1,2

Further results showed that 7 products contained too much arsenic and 2 contained too much lead, while 13 contained too much cadmium—all exceeding limits set by US Pharmacopeia.¹

Pharmacists and health care providers can recommend healthy foods that are rich in choline and iodine if individuals that are pregnant, lactating, or planning pregnancy are not receiving enough in prenatal vitamin supplements. Foods that are high in choline include organ meat, fish, caviar, beef, chicken turkey, whole eggs, cottage cheese, shiitake mushrooms, soybeans, wheat germ, cruciferous vegetables, almonds, lima beans, red potatoes, kidney beans, and quinoa. Additionally, foods high in iodine include seaweed, kombu kelp, wakame, nori, cod, dairy, iodized salt, shrimp, tuna, eggs, prunes, and lima beans.^3,4

“We're one of the first studies to measure the actual amounts of choline and iodine in a large sample of prenatal supplements. The presence of contaminants, especially cadmium, was also concerning. Our findings highlight a significant gap between what's listed on the labels and what’s actually in the products, underscoring the urgent need for stronger regulatory oversight in this area,” said Borgelt, in a news release.¹

REFERENCES

1. Less than 50% of many prenatal supplements have the adequate amount of choline and iodine. EurekAlert!. News release. November 21, 2024. Accessed December 18, 2024. https://www.eurekalert.org/news-releases/1065752.

2. Content of selected nutrients and potential contaminants in prenatal multivitamins and minerals: an observational study. The American Journal of Clinical Nutrition. News release. November 19, 2024. Accessed December 18, 2024. https://www.sciencedirect.com/science/article/abs/pii/S0002916524008852?via%3Dihubhttps://www.sciencedirect.com/science/article/abs/pii/S0002916524008852?via%3Dihub.

3. 16 Foods That Are High in Choline. Healthline. News release. December 17, 2024. Accessed December 18, 2024. https://www.healthline.com/nutrition/foods-with-choline.

4. 9 Healthy Foods That Are Rich in Iodine. Healthline. News release. February 1, 2023. Accessed December 18, 2024. https://www.healthline.com/nutrition/iodine-rich-foods.