British journal argues against prenatal multis, CRN counters

LONDON - Prenatal multivitamins are an "unnecessary expense" according to a review published by BMJ earlier this week, which advised pregnant women to focus on supplementing with folic acid and vitamin D supplements while improving their overall diet.

"Good nourishment, both before and during pregnancy, is essential for the health of the mother and her unborn child," BMJ's Drug and Therapeutics Bulletin reported.  "And deficiency in key nutrients has been linked to various complications of pregnancy and birth, including pre-eclampsia, restricted fetal growth, neural tube defects, skeletal deformities and low birthweight."

According to BMJ, prenatal supplements oftentimes contain more than 20 vitamins and minerals, such as vitamins B1, B2, B3, B6, B12, C, D, E, K, folic acid, iodine, magnesium, iron, copper, zinc and selenium, at a cost of almost $20 per month.

BMJ advocated supplementation of folic acid and vitamin D, but nothing else. They may have misssed supplements crucial to healthy fetal development, such as iodine and iron, argued an American trade association representing the dietary supplement industry.

"Reputable medical organizations, including the American Academy of Pediatrics, the Endocrine Society and the American Thyroid Association, recommend that pregnant women take a multivitamin as a way to assure they are getting adequate nutrients such as folic acid and iodine that are critical for the development and well-being of the fetus, as well as for their own health," countered Duffy MacKay, SVP scientific and regulatory affairs for the Council for Responsible Nutrition, a U.S. association representing the dietary supplement industry. "In fact, iodine is now recognized as a nutrient so critical to the cognitive development of the baby during pregnancy that CRN recently developed guidelines urging the dietary supplement industry to ensure that prenatal multivitamins contain at least 150 mcg of iodine daily," he said.

"The scientific evidence is clear — requirements for folic acid, calcium, iron, iodine, protein and other nutrients go up during pregnancy — and the consequences of not getting enough can be significant for both mother and child," MacKay added. "In addition, we know from the 2015-2020 Dietary Guidelines that most Americans fall short in key nutrients, and pregnancy is no exception, especially if you consider appetite changes and nausea that can accompany pregnancy."

BMJ reviewed current UK guidance for vitamin supplements recommended for pregnant women, and 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, 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, BMJ noted, with little of the trial data showing any impact on reducing the risk of complications of pregnancy or birth. Nevertheless, BMJ advised a daily dose of 10 micrograms is recommended throughout pregnancy and breastfeeding.

As to the other supplements, BMJ suggested there was no evidence of any obvious clinical benefit for most women who are well nourished, and high doses of vitamin A may harm the developing fetus. "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," BMJ stated. "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."

BMJ's arguments against supplementing a diet with a multivitamin may be misguided, CRN argued.

"It is unfortunate that, in addition to disregarding the immense value a multivitamin and its ingredients can provide pregnant women, the authors fail to acknowledge that conducting randomized controlled trials on a multivitamin in pregnant women would be unethical as you cannot deprive a pregnant woman of essential nutrients," noted MacKay. "When the totality of all available evidence is considered, the value of nutrient supplementation during pregnancy makes a clear case."