Ninety percent of pregnant women do not get the nutrients they require during pregnancy from food alone and must turn to supplements to plug the nutrient gap, according to a study published in The American Journal of Clinical Nutrition.
Perhaps more shocking, however, is the study’s secondary finding that 99% of the affordable dietary supplements on the US market do not contain appropriate doses of key micronutrients that are required to make up for the nutritional imbalance in a pregnant woman’s diet. This includes general vitamin, mineral, and supplement brands and products that are specifically marketed to pregnant women.
Lead author Katherine Sauder, associate professor of paediatrics in the University of Colorado School of Medicine, said the researchers had been surprised by the outcome, especially because they only looked at the six nutrients mostly strongly linked to pregnancy outcomes.
“We assumed many products would get those top six right, but we were wrong,” she said. “What’s further concerning is that other nutrients are also important. If we could only find one product meeting the top six nutrients, we’re unlikely to find any meeting the rest of the nutrients.”
Products provide excessive or insufficient amounts of key nutrients
For the study, researchers at the University of Colorado Anschutz Medical Campus analysed data from the National Institute of Health’s (NIH) Environmental influences on Child Health Outcomes (ECHO) programme, using 24-hour dietary recall data for 2,450 pregnant women.
They then analysed this food and drink intake data, determining how much vitamin A, vitamin D, folic acid, calcium, iron, and omega-3 fatty acids each participant was getting from diet alone.
The scientists calculated how much supplementation the women needed to meet the nutritional guidelines recommended by the NIH during pregnancy and, using the NIH Dietary Supplement Label Database, compared this with information on the composition of more than 20,000 vitamin, mineral, and supplement products on the US market.
They found that more than 12,000 products – including around 400 that were specifically marketed as prenatal supplements – contained the target doses of just one nutrient and fewer than 100 contained target doses for five nutrients.
“We posit the large US dietary supplement market is not meeting the nutrient needs of pregnant women,” concluded the authors.
Ninety percent of products provided more than the upper limit for folic acid, fostering concerns about over-supplementation of this nutrient, which can potentially cause negative health impacts for the mother-to-be and the baby. About 50% contained over 27 mg of iron, which would cause an excessive intake in almost one-third (30%) of the participants.
High cost of adequate supplementation
Just one product contained the target doses of all six nutrients – Shaklee Life with Iron – but it came with a high price tag: consumers would have to take seven tablets every day to reach the target dose. This would cost $6.87 per day or around $1,850 for a nine-month supply.
Another seven products, two of which were prenatal, contained all six nutrients but had the target doses for only five nutrients. However, by the time of writing the study, five of these products were no longer available or had changed their formulations.
Of the two that remained, the scientists determined that one – GNC Women’s Multivitamin Prenatal Plus DHA & Iron – would provide an excessive amount of folic acid for all of the study participants, while the other product – Carlson Women’s Omega Multi – would not provide enough calcium for almost half (46%) of adolescent participants aged 14 to 18 years old and 13% of participants aged 19 to 50 years old.
Evidence-based supplement targets must be formalised
Over 70% of pregnant women in the US take dietary supplements, meaning that evidence-based targets for supplementation for pregnant women must be urgently formalised, said the researchers.
According to Sauder, the study’s findings highlighted the need for prenatal vitamin products that are low-cost and convenient, while still containing the optimal amounts of key nutrients. In light of the study’s findings, Sauder had a message for the nutraceutical industry.
“Please reconsider the doses included in supplements, particularly the ones that exceed 100% of the daily value,” she said. “Those high doses are rarely needed for general consumers without special medical circumstances.
“Nutrition scientists can partner with manufacturers to develop product doses based on research findings. Together, we can create products that provide the right nutrients at the right doses to promote health of pregnant women.”
