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Multivitamin and mineral supplements in pregnancy are unnecessary expense, review finds

BMJ 2016; 354 doi: https://doi.org/10.1136/bmj.i3821 (Published 12 July 2016) Cite this as: BMJ 2016;354:i3821
  1. Zosia Kmietowicz
  1. The BMJ

Expensive multivitamin and mineral supplements targeted at pregnant women are a waste of money and do not result in better outcomes for mother or baby, an evidence review has concluded. Women should instead focus on improving their overall diet and taking folic acid and vitamin D supplements, both of which are relatively cheap, it said.

Many multivitamin and mineral supplements are heavily marketed to women at all stages of pregnancy to guard against a range of problems that can result from nutritional deficiency, including pre-eclampsia, restricted fetal growth, neural tube defects, skeletal deformities, and low birth weight, said the review in the Drug and Therapeutics Bulletin.1

These supplements typically contain 20 or more vitamins and minerals, such as vitamins B1, B2, B3, B6, B12, C, D, E, and K, folic acid, iodine, magnesium, iron, copper, zinc, and selenium, and cost around £15 (€17.60; $19.50) a month.

To examine the current UK guidance on vitamin supplements recommended for pregnant women and the evidence behind it, the bulletin reviewed the published research on folic acid, vitamin D, iron, vitamins C, E, and A, and multivitamin supplements.

It found that folic acid had the strongest evidence to support national UK guidance, which recommends that women take 400 micrograms of folic acid daily from before pregnancy until 12 weeks into it. A daily dose of 5 mg is recommended for women at higher risk of having a child with neural tube defects—women who have neural tube defects themselves or have a family history of the condition, or who have diabetes.

The evidence for vitamin D supplementation was less clear cut, as few of the trial results showed any effect on reducing the risk of complications from pregnancy or birth, the review found. Nevertheless, a daily dose of 10 micrograms is currently recommended throughout pregnancy and breast feeding.

The review found no evidence that any of the other supplements had an obvious clinical benefit for most women who are well nourished. High doses of vitamin A may harm the developing fetus, it found. And the available data did not support the use of multivitamin supplements in most pregnant women, it added.

Much of the evidence on which the marketing claims for multivitamin supplements are based came from studies carried out in low income countries, where women are more likely to be undernourished or malnourished than women in the United Kingdom, the review said, and a good deal of the evidence derived from observational studies that were subject to bias and can establish only an association, not a cause.

“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 review concluded.

References

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