Most best-selling prenatal supplements contain amounts of nutrients that differ from product labels, according to a report.
The U.S. Government Accountability Office (GAO) tested 12 prenatal supplements for amounts of folic acid, iodine, iron, or vitamin A, C, or E, the nutrients crucial during pregnancy. The researchers selected products from "best-selling" or "top-rated" lists from the websites of major retailers.
Of those, 11 products had at least one of these nutrients in amounts outside of acceptable deviations from the amount stated on the label. This could lead to a pregnant individual consuming too much or too little of these nutrients.
Having adequate levels of folic acid before and during pregnancy can prevent major birth defects in the baby's brain and spine.
Pregnant women need 600 micrograms of folic acid each day. Because it's hard to get this much of the nutrient from food alone, the American College of Obstetricians and Gynecologists (ACOG) recommends taking a daily prenatal vitamin with at least 400 micrograms starting at least a month before pregnancy.
However, consuming too much folic during pregnancy may slow a child's brain development and increase the risk of insulin resistance.
In other tested products, deviations from the amounts of nutrients stated on the labels are unlikely to be a health concern, according to the report.
Vitamin E varied the most between different products, ranging from 28% to 332% of the amount stated on the label.
Vitamin A was the nutrient most frequently found in amounts outside the acceptable deviations from the label value. In nine of the 12 supplements tested, the amounts of vitamin A differed from the product label.
The GAO detected traces of two heavy metals — lead or cadmium — in six tested products. However, the report says the amounts are not likely to cause a health concern based on metrics used by the Food and Drug Administration (FDA).
The Council of Responsible Nutrition (CRN), a trade association representing the dietary supplement industry, said the GAO’s report strikes an unnecessary alarmist note.
“The worst possible outcome would be for women to read this report and decide not to take prenatal supplements, when research shows the critical benefits these nutrients provide in the form of supplementation,” CRN’s Andrea Wong, senior vice president for scientific and regulatory affairs, said in a statement.
Calls for stricter regulations
Unlike medication, dietary supplements are not generally required to be registered with the FDA and undergo rigorous evaluation for safety or effectiveness. Because supplements are regulated as a special category of food, the FDA has limited information about them to inform its post-market inspections and oversight.
A 2023 study found that most prenatal supplements in the United States did not contain target doses of critical nutrients needed during pregnancy. Some products were found to put pregnant participants at risk for excessive folic acid intake or inadequate calcium intake.
The ACOG does not recommend taking more than the recommended amount of prenatal vitamins daily to make up for deficiencies, as some multivitamin ingredients, like vitamin A, can cause birth defects at higher doses.
As most prenatal supplements do not contain the amounts of crucial nutrients stated on the label, the report's authors recommend that Congress consider measures for allowing the FDA to oversee dietary supplements.
- U.S. Government Accountability Office. Prenatal Supplements: Amounts of Some Key Nutrients Differed from Product Labels.
- The American College of Obstetricians and Gynecologists. Nutrition During Pregnancy.
- CDC. Folic Acid.
- National Library of Medicine. Effect of maternal high dosages of folic acid supplements on neurocognitive development in children at 4-5 y of age: the prospective birth cohort Infancia y Medio Ambiente (INMA) study.
- National Library of Medicine. Association between maternal folate concentrations during pregnancy and insulin resistance in Indian children.