Few dietary supplements in US provide key nutrients for pregnancy

Key takeaways:

• Of 20,547 dietary supplements/prenatal products in the U.S., only one contained target doses for all nutrients.
• The supplement with target doses for all nutrients is more expensive and requires more tablets per serving.

Almost no dietary supplements available in the U.S. provide key nutrients in required doses for pregnant women, which can lead to risk for inadequate nutrient intake from foods alone, researchers reported.

In a study, published in The American Journal of Clinical Nutrition, researchers analyzed data from 24-hour dietary recalls from 2007 to 2019 from 2,450 pregnant women (mean age, 28.1 years) aged 14 to 50 years. Researchers estimated the usual intake of vitamin A, vitamin D, folate/folic acid, calcium, iron and omega-3 fatty acids from foods alone.

“We aimed to identify the doses of key nutrients that pregnant women should consume from dietary supplements to bridge the gap between food-based intake and estimated requirement,” Katherine A. Sauder, PhD, a biobehavioral health researcher at the Lifecourse Epidemiology of Adiposity and Diabetes Center at the University of Colorado Anschutz Medical Campus, and colleagues wrote. “Our analysis considered six nutrients with the strongest evidence for a potential benefit for maternal-child health outcomes: vitamin A, vitamin D, folate/folic acid, calcium, iron and omega-3 fatty acids.”

Sauder and colleagues also calculated the target supplementation doses required to shift 90% of pregnant participants to consume above the estimated average requirement and keep 90% below the tolerable upper limit. Utilizing the Dietary Supplement Label Database, researchers abstracted 20,547 dietary supplementation products, of which 421 were labeled as prenatal products. Dietary intake analyses were conducted separately for participants aged 14 to 18 years and those aged 19 to 50 years.

Overall, 6,106 recalls were completed. Inadequate intake risk for both younger and older participants was 83% to 96% for vitamin D and iron. For omega-3 fatty acids, the risk for inadequate intake was 67% for the younger participants and 50% for the older participants. For calcium, the risk was 55% and 30%, respectively; for folate/folic acid, it was 45% and 34%, respectively; and for vitamin A, the risk was 42% and 26%, respectively, the researchers reported.

Target doses for supplementation were 198 µg or higher retinol activity equivalents of total vitamin A, 7 µg to 91 µg for vitamin D, 169 µg to 720 µg for folate/folic acid, 383 mg to 943 mg for calcium, 13 mg to 22 mg for iron and 59 mg or higher for omega-3 fatty acids.

Of 20,547 dietary supplements/prenatal products in the U.S., 0.3% contained all six required nutrients, and seven contained target doses for five nutrients. Only one dietary supplement, which was not a prenatal product, contained target doses for all six nutrients, according to researchers. However, this supplement is expensive (about $200 per month) and requires seven tablets per daily serving, the researchers wrote.

“This study provides practical guidance for clinicians and pregnancy women seeking to achieve the recommended nutrient intake to support maternal/offspring health,” the researchers wrote. “Nearly all pregnant participants were at risk of inadequate intake of [at least] one key nutrients from foods alone and thus may benefit from a carefully selected dietary supplement.”