Prenatal supplements which meet the target doses of vitamin A, vitamin D, folate, calcium, iron, and omega-3 fatty acids in the U.S. population are extremely scarce, according to a study published in the American Journal of Clinical Nutrition.
 
Researchers recruited a population of 2,450 participants from 2007-2019, who conducted 24-hour dietary recalls. This helped to calculate averages of what people were lacking in the six nutrients assessed in the study.
 
In total, researchers tested 20,547 dietary supplements, including 421 products specifically labeled as prenatal. Only 69 products included all six of the nutrients assessed. A mere seven products, two of which were labeled as prenatal supplements, contained target doses for five nutrients, and only one product met target doses for all six nutrients by the population’s standards.
 
Further, many supplements left pregnant mothers at risk of excessive nutrient intake. “Ninety percent contain more than the UL [upper limit] for folic acid, fostering concerns about over-supplementation of folic acid that can potentially induce adverse maternal/offspring outcomes. About 50% contain >27mg iron, which would induce excessive intake in ∼30% of our participants,” the authors wrote. The majority of products didn’t contain omega-3 fatty acids, while some didn’t contain any iron.
 
“Dietary supplements are necessary for the vast majority of pregnant females to meet nutrient targets, but the options available in the U.S. are not meeting that need,” said Katherine Sauder, PhD, lead author of the study. “Consumers can use the target doses we provide to pick the better options from the ones available to them, and manufacturers can adjust formulations to meet these needs.”
 
The target doses for the population study were: ≥198 mcg retinol activity equivalents of total vitamin A (with ≤2063 mcg preformed retinol); 7-91 mcg of vitamin D; 169-720 mcg dietary folate equivalents of folic acid; 383-943 mg calcium; 13-22 mg iron, and ≥59 mg of omega-3 fatty acids.
 
When it came to defining a suitable supplement that meant target dosages, the researchers were in search of a kind of ‘gold standard’ or ‘default’ supplement that would be optimal for 90% of women based on what they ate in their 24-hour dietary recall. “Or, you can think of it as a supplement that works for a woman on 90% of days,” said Sauder. “No one eats exactly the same thing every single day, so the amount of supplementation someone needs varies day by day.”   
 
Part of a Bigger Picture
 
Sauder’s recommendation to both consumers and the industry is to avoid excessive nutrient intake, and emphasize attention on Supplement Facts panels. Many upper limits are not far above recommended daily intakes, and there is a lack of data about how harmful excessive nutrient intakes may be toward mother-child pairings during pregnancy. “Many people are taking high doses of vitamins thinking more is better, but we simply don’t know that,” Sauder said.
 
Additionally, she hopes the study will lead all manufacturers to deepen their partnerships with the scientific community to develop products based on population-based needs.
 
 “Dietary supplements are supposed to supplement the nutrients obtained from foods, not replace them. Unless someone has a special medical situation, getting 100% or more of the daily value from a supplement is unnecessary, and potentially harmful. At the same time, when a product does not provide a high enough dose, consumers think they are getting enough but still falling short. Aiming for 25% to 75% for most nutrients is generally enough.”
 
“We appreciate the study authors’ efforts to add to the body of research on nutrient needs and supplementation during pregnancy,” said Andrea Wong, PhD, CRN’s vice president of scientific and regulatory affairs. “This latest research reinforces what skilled dietitians and nutritionists have been saying for years—dietary supplements, even prenatal supplements—are simply ‘supplements’ to a healthy diet, not substitutes,” said Wong. “While these critical products absolutely do fill some nutritional gaps, they are not intended to replace healthy eating, and certainly not during the critical time of pregnancy.”
 
“Including every key nutrient in a single product at levels to meet the needs of nearly every woman during pregnancy is, of course, challenging. These products absolutely increase the daily intake of these nutrients, but even as food patterns vary across the population, one product should not be expected to provide exactly 100 percent of each person’s precise nutritional needs.”