Some multivitamin and mineral supplements may be “unnecessary and expensive”, a recent study has determined.
A review of the available evidence, published in this month’s issue of the Drug and Therapeutics Bulletin, found that despite strong marketing claims, the evidence suggests these do not necessarily translate into better outcomes for mother or baby. Furthermore, the researchers criticise misleading claims, aimed at “vulnerable” pregnant women.
Women should instead focus on improving their overall diet, as well as taking folic acid and vitamin D supplements, both of which are available at relatively low cost, say the researchers.
While deficiency in key nutrients has been linked to various complications of pregnancy and birth, including preeclampsia, restricted fetal growth, neural tube defects, skeletal deformities and low birthweight, the role of multi-vitamin and mineral supplements as marketed to women for all stages of pregnancy to guard against these sorts of problems has been the subject of debate.
The review, of all previously published research on folic acid, vitamin D, iron, vitamins C, E, and A, and multivitamin supplements, found that folic acid had the strongest evidence to support national UK guidance, which recommends that women take 400 ug of folic acid daily from before, until 12 weeks of, pregnancy.
A daily dose of 5 mg is recommended for those women at higher risk of having a child with neural tube defects - those who have neural tube defects themselves, a family history of the condition, or who have diabetes. The evidence for vitamin D supplementation was less clear-cut, with little of the trial data showing any impact on reducing the risk of complications of pregnancy or birth, the review found. Nevertheless, a daily dose of 10 ug is recommended throughout pregnancy and breastfeeding.
There was no evidence of any obvious clinical benefit of any other supplements for most women who are well-nourished, and they note that high doses of vitamin A may harm the developing fetus. Furthermore, the available data don’t support the use of multivitamin supplements in most pregnant women either.
Incidentally, the authors suggest that most of the evidence used to support marketing claims by vitamin manufacturers comes from lower-income countries where mothers may not be as well nourished. This suggests that if a woman is in danger of having a sub-par daily diet, vitamin supplements would in that case be essential.
“We found no evidence to recommend that all pregnant women should take prenatal multi-nutrient supplements beyond the nationally advised folic acid and vitamin D supplements, generic versions of which can be purchased relatively inexpensively,” say the researchers.
“For most women who are planning to become pregnant or who are pregnant, complex multivitamin and mineral preparations promoted for use during pregnancy are unlikely to be needed and are an unnecessary expense… The marketing of such products does not appear to be supported by evidence of improvement in child or maternal outcomes,” conclude the authors.
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