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ORIGINAL RESEARCH COMMUNICATION |
1 From the Department of Pediatrics, the School of Medicine and Public Health, the University of Wisconsin, Madison, WI. 2 Reprints not available. Address correspondence to Department of Pediatrics, School of Medicine and Public Health, University of Wisconsin, Madison, WI 53792-4108. E-mail: frgreer{at}pediatrics.wisc.edu.
This supplement is the product of a symposium entitled "Methyl Donors, Iodine, and DHA—Is Maternal Supplementation Beneficial?," which was held at the annual meeting of the American Society for Nutrition in San Diego, CA, on 6 April 2008. The symposium summarized the current evidence on whether or not pregnant and lactating women in developed countries would benefit from increasing their intake of nutrients through either food choices or dietary supplements. Each of the participants at the symposium was asked to establish a research agenda for the questions raised in their presentations.
It is generally accepted that nutrition during pregnancy and lactation is important for the health of the mother and the growth and development of her offspring. However, there have been few randomized clinical trials of nutrient supplementation during pregnancy and lactation. Much of the data that support this notion is observational in humans or is derived from animal models. Human data that support the requirement for specific nutrients during pregnancy and lactation are limited beyond the need to avoid overt deficiency diseases, even though suboptimal intakes of nutrients are likely to be much more common than observed. Even fewer studies have assessed functional outcomes in relation to supplementation with a specific nutrient. Except for offering evidence-based advice on weight gain during pregnancy, the Institute of Medicine report recommends only that all US women consume supplements of iron and folate during pregnancy (1). The article by Picciano and McGuire (2) reviews what is known about the current use of dietary supplements in pregnant and lactating women in North America. Again, the lack of data on the use of dietary supplements by this population is striking.
The remaining papers presented at this symposium consider 3 specific nutrients: methyl donors, iodine, and docosahexaenoic acid (DHA; 22:6n–3), all nutrients for which there is new evidence for increased dietary importance during pregnancy and lactation and all of which are important for neurodevelopment of the fetus and infant. The article by Zeisel (3) emphasizes the fact that either a deficiency or an excess of methyl donors in the diet of pregnant and lactating women can have a profound impact on offspring through gene polymorphisms or epigenetic mechanisms. This is timely, given the continued concerns about the folic acid intake of women of childbearing age in the United States, which in recent years has declined despite increased food fortification with folate (4). Although the current recommended intake for folic acid intake for women of childbearing age to prevent neural tube defects is 400 µg/d, new recommendations are expected soon from the US Preventive Services Task Force.
The article by Zimmermann (5) reviews what is known about the effects of severe maternal iodine deficiency on offspring and what is largely not known of the effects of mild-to-moderate iodine deficiency on offspring. More information on the effects of mild-to-moderate iodine deficiency in populations in which severe iodine deficiency is rare is needed, particularly with regard to neurodevelopmental outcomes. This is particularly important, given the new recommendations of the American Thyroid Society (6) to supplement all pregnant women living in the United States or Canada with 150 µg iodine.
The article by Carlson (7) notes that there are few studies of DHA supplementation of pregnant and lactating women, although supplements of DHA are now being marketed to this group. However, the number of observational studies linking higher DHA status to favorable infant developmental outcomes increases the need for more experimental trials. The DHA supplementation studies of pregnant women have shown that it may be more than a simple matter of maternal DHA intake, as some of the marked variability in red blood cell DHA in the mother and her fetus may be accounted for by the variability in maternal biosynthesis rates as well as by the maternal-to-fetal transfer rates of DHA. This suggests that genetic differences may be important in these processes. The potential benefits to the fetus and infant of DHA supplements for pregnant or lactating women are suggested largely by randomized controlled studies in which supplements were given orally to infants after birth. Because it appears that preterm infants may benefit most from DHA-supplemented formula after birth, one wonders about the impact of feeding a preterm infant the mother's breastmilk in the absence of maternal or infant DHA supplements, which is the current practice in neonatal intensive care units in the United States. Carlson concluded her article with a number of unanswered questions and a proposed research agenda for answering some of these questions. (Other articles in this supplement to the Journal include references 2, 3, 5, 7, and 8.)
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ACKNOWLEDGMENTS |
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REFERENCES |
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This article has been cited by other articles:
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  M. F. Picciano and M. K McGuire Use of dietary supplements by pregnant and lactating women in North America Am. J. Clinical Nutrition, February 1, 2009; 89(2): 663S - 667S. [Abstract] [Full Text] [PDF]
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M. B Zimmermann Iodine deficiency in pregnancy and the effects of maternal iodine supplementation on the offspring: a review Am. J. Clinical Nutrition, February 1, 2009; 89(2): 668S - 672S. [Abstract] [Full Text] [PDF]
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S. H Zeisel Importance of methyl donors during reproduction Am. J. Clinical Nutrition, February 1, 2009; 89(2): 673S - 677S. [Abstract] [Full Text] [PDF]
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S. E Carlson Docosahexaenoic acid supplementation in pregnancy and lactation Am. J. Clinical Nutrition, February 1, 2009; 89(2): 678S - 684S. [Abstract] [Full Text] [PDF]
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S. H Zeisel Is maternal diet supplementation beneficial? Optimal development of infant depends on mother's diet Am. J. Clinical Nutrition, February 1, 2009; 89(2): 685S - 687S. [Abstract] [Full Text] [PDF]
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