The importance of physiological supply of folate is well recognized in human health; the crucial roles of folate in one-carbon metabolism for physiological DNA synthesis and cell division, as well as in the conversion of homocysteine (Hcy) to methionine, and subsequently, to S-adenosylmethionine, have been convincingly demonstrated. Improved folate status may reduce the risk of macrocytic anaemia, cardiovascular diseases, neuropsychiatric disorders and adverse pregnancy outcomes. Inadequate folate status results in a decrease in the methylation cycle and in increased blood levels of the neurotoxic Hcy. The aim of this review is to provide insight into the influence of folate status on pregnancy health outcomes, and to consider increasing evidence of a link between the extent of genome/epigenome damage and elevated risk for adverse obstetrical endpoints.Pregnant women are at risk for folate insufficiency because of the increased need for folate for rapid fetal growth, placental development and enlargement of the uterus. Inadequate folate status may cause fetal malformations, impaired fetal growth, pre-term delivery and maternal anaemia. Even some diseases of the placenta may arise from folate deficiencies. Fetal growth seems to be vulnerable to maternal folate status during the periconception period, because it has the potential to affect both the closure of the neural tube and several epigenetic mechanisms within the placenta and the fetus. Mainly on the basis of the well recognized link between maternal folate status and fetal neural tube defects, women are advised to receive folic acid supplement during the periconceptional period. Because an adequate folate supply seems to play an important role in the implantation and development of the placenta and in improving endothelial function, folic acid supplementation in the late first trimester or early second trimester might also be beneficial.
A systematic review was conducted to summarize the evidence currently available from randomized controlled trials (RCTs) concerning the effect of iron intake of infants, children and adolescents on measures of cognitive development and function. The Cochrane Library, MEDLINE and Embase were searched up to and including February 2010. Studies were also identified by checking the bibliographies of the articles retrieved. All RCTs with an adequate control group in which iron supply was provided by natural food sources, fortified foods, formula or supplements to infants, children or adolescents until the age of 18 years were considered for inclusion. No language restrictions were applied. Fourteen studies met the selection criteria. Twelve out of these 14 studies had a high or moderate risk of bias. A large degree of heterogeneity of study populations, iron dosages and outcome measures precluded performing a quantitative meta-analysis. Overall, the studies suggest a modest positive effect of iron supplementation on cognition and psychomotor outcomes in anemic infants and children after supplementation periods of at least 2 months of duration.
The most widely used method for estimating dietary zinc requirements is the factorial approach, in which it is assumed, in adults, that the physiological zinc requirement is the lowest intake that replaces endogenous zinc losses. Presented here are the results of two reviews: a narrative review of zinc losses from the human body and a systematic review of factors affecting zinc bioavailability in adult and elderly populations. The narrative review presents data on losses from integumental and excretory routes, obtained from 29 papers published up to April 2013. The systematic review includes a total of 87 publications describing dietary factors that impact zinc bioavailability, 30 of which examined phytate. A meta-analysis revealed an overall lowering of fractional zinc absorption by 0.14 (45% of control values) when the phytate : zinc molar ratio of the test meal or diet was greater than 15. These reviews provide a comprehensive resource for use in the setting of human dietary zinc requirements and emphasize the need for more high-quality data to improve estimates of zinc losses and gains.
Micronutrient recommendations should be regularly updated to reflect new scientific nutrition and public health evidence. The strategy of priority setting described in this paper will be a helpful procedure for policy makers and scientific advisory bodies.
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