Effect of gestational zinc deficiency on pregnancy outcomes: summary of observation studies and zinc supplementation trials

Investigation of the levels of essential and non-essential metals in women with and without abortion history: A study based on the Persian population of the Shahrekord cohort

Spontaneous abortion is a serious threat to the mothers' physical and mental well-being. The cause of spontaneous abortion is multifactorial disease. Prenatal non-essential metal exposure, particularly heavy metals, has been suggested to be associated with adverse pregnancy and birth outcomes. The purpose of this study was to investigate the relationship between the concentration of essential and non-essential metals including Pb, As, Zn, and Se and the risk of spontaneous abortion. In this case-control study the levels of Pb, As, Zn, and Se in the whole blood of 60 women with spontaneous abortion (case group) and also 60 women without spontaneous abortion (control group) were measured by atomic absorption spectrophotometry. Results revealed statistically significant reductions (P < 0.001) in whole blood levels of Zn and Se as well as the levels of As and Pb had a substantial elevation (P < 0.001) in cases compared to controls. According to the findings, repeated spontaneous abortion may be influenced by increasing whole blood levels of heavy metals such as As (OR = 17.53, P = 0.001) and Pb (OR = 15.58, P = 0.001) as well as decreasing levels of vital micronutrients Zn (OR = 0.20, P = 0.001) and Se (OR = 0.14, P = 0.001). The results of this study support the idea that limiting intake of non-essential metals during pregnancy can decrease the risk of spontaneous abortion. Overall, the information presented is expected to help plan future fundamental and applied investigations on the spontaneous abortion.

Zinc deficiency among pregnant women around Lake Awasa, Hawassa City, Ethiopia: a cross-sectional analysis

Zinc deficiency (ZD) during pregnancy has far-reaching consequences on the mother, fetus and subsequent child survival. Therefore, the present study aimed to assess the prevalence and associated factors of ZD among pregnant women around Lake Awasa, Hawassa City, Ethiopia. To this end, a facility-based cross-sectional study was conducted on 333 randomly sampled pregnant women from 08 April to 08 May 2021. The socio-economic, dietary intake, water, sanitation and hygiene, obstetric, and maternal health data were collected through face-to-face interviews. Moreover, on-spot blood and stool samples were taken. Descriptive statistics and binary and multivariable logistic regression analysis were conducted. The prevalence of ZD was 58⋅6 % (95 % CI 53⋅31, 63⋅89). The poorest (AOR = 3⋅28; 95 % CI 1⋅26, 8⋅50) and poor (AOR = 2⋅93; 95 % CI 1⋅14, 7⋅54) wealth quintiles, four of more family size (AOR = 1⋅84, 95 % CI 1⋅10, 3⋅35), poor dietary diversity (AOR = 4⋅11; 95 % CI 2⋅11, 7⋅62), not eating snacks (AOR = 3⋅40; 95 % CI 1⋅42, 8⋅15), not consuming fish (AOR = 3⋅53; 95 % CI 1⋅65, 7⋅56) and chicken (AOR = 2⋅53; 95 % CI 1⋅31, 4⋅88) at least once a month, and intestinal parasitic infection (AOR = 2⋅78; 95 % CI 1⋅52, 5⋅08) predicted zinc deficiency. In conclusion, ZD is a public health problem among pregnant women around Lake Awasa. The present study demonstrated that poor socio-economic status, large family size, poor nutritional practices and intestinal parasitic infection determine the zinc status in the present study area. The findings suggest the need for further analysis to deepen the understanding about ZD and consideration of livelihood in interventions to prevent and control ZD among pregnant women in Hawassa City, Ethiopia.

Applying Zinc Nutrient Reference Values as Proposed by Different Authorities Results in Large Differences in the Estimated Prevalence of Inadequate Zinc Intake by Young Children and Women and in Cameroon

Nutrient reference values (NRVs) for zinc set by several expert groups differ widely and may affect the predicted prevalence of inadequate zinc intake. We examined this possibility using NRVs published by four different authorities and nationally representative dietary intake data collected among children aged 12–59 months and women in Cameroon. Usual zinc intake was estimated from 24 h recall data using the National Cancer Institute method. Prevalences of total zinc intake below the dietary requirement and of “absorbable zinc intake” below the physiological requirement were estimated using NRVs published by the World Health Organization (WHO), US Institute of Medicine (IOM), International Zinc Nutrition Consultative Group (IZiNCG), and European Food Safety Authority (EFSA). The prevalence of inadequate zinc intake ranged from 10% (IZiNCG—physiological requirement, 95% CI 7–13%) to 81% (EFSA—physiological requirement, 95% CI 78–84%) among children and 9% (WHO—physiological requirement, 95% CI 8–11.0%) to 94% (IOM—physiological requirement, 95% CI 92–95%) among women These differences in the prevalence of inadequate intake translated into sizeable differences in the predicted benefit and cost-effectiveness of zinc fortification programs. Depending on the NRVs applied, assessments differ regarding the need for and design of zinc fortification programs. Efforts are needed to harmonize NRVs for zinc.

Zinc homeostasis in immunity and its association with preterm births

Preterm birth is among the most common adverse pregnancy outcomes and is the leading cause of neonatal mortality and morbidity. While trace elements are essential for humans, their specific roles in the prenatal period remain unexplored. Zinc, a ubiquitous element plays a pivotal role in protein synthesis, cell division, nucleic acid metabolism, apoptosis, ageing, reproduction, immunological as well as antioxidant defense mechanism. Although zinc quantities are very small in body tissue, it is involved in every conceivable biochemical pathway which is critical for the performance of various functions necessary to sustain life. Owing to the multifactorial role of zinc, it is not possible to attribute a certain zinc dependent mechanism in pre-term births. Although the effect of zinc deficiency on immunity, its impact on maternal function and health as well as its role in the developing foetus is well documented, much less attention has been given to the understanding of micronutrient zinc homeostasis in immunity and its association with preterm births. Despite extensive research, the pathway by which zinc regulates pregnancy outcomes as well as the function of immune cells in controlling the delivery status (term/ preterm) is still obscure. The present review aims to focus on the understanding of relationship of micronutrient zinc homeostasis in immunity and its association with preterm births.

Role of zinc in female reproduction

Zinc is a critical component in a number of conserved processes that regulate female germ cell growth, fertility, and pregnancy. During follicle development, a sufficient intracellular concentration of zinc in the oocyte maintains meiotic arrest at prophase I until the germ cell is ready to undergo maturation. An adequate supply of zinc is necessary for the oocyte to form a fertilization-competent egg as dietary zinc deficiency or chelation of zinc disrupts maturation and reduces the oocyte quality. Following sperm fusion to the egg to initiate the acrosomal reaction, a quick release of zinc, known as the zinc spark, induces egg activation in addition to facilitating zona pellucida hardening and reducing sperm motility to prevent polyspermy. Symmetric division, proliferation, and differentiation of the preimplantation embryo rely on zinc availability, both during the oocyte development and post-fertilization. Further, the fetal contribution to the placenta, fetal limb growth, and neural tube development are hindered in females challenged with zinc deficiency during pregnancy. In this review, we discuss the role of zinc in germ cell development, fertilization, and pregnancy with a focus on recent studies in mammalian females. We further detail the fundamental zinc-mediated reproductive processes that have only been explored in non-mammalian species and speculate on the role of zinc in similar mechanisms of female mammals. The evidence collected over the last decade highlights the necessity of zinc for normal fertility and healthy pregnancy outcomes, which suggests zinc supplementation should be considered for reproductive age women at risk of zinc deficiency.

Effect of maternal zinc deficiency on offspring health: The epigenetic impact

BACKGROUND

Zinc deficiency is associated with adverse effects on maternal health and pregnancy outcomes. These consequences have been reported over the years from zinc supplementation trials and observational studies whereby outcomes of maternal, foetal and infant health were measured. Owing to the importance of zinc in the functions of epigenetic enzymes, pre-clinical studies have shown that its deficiency could disrupt biological activities that involve epigenetic mechanisms in offspring. Thus, this review assessed the link between epigenetics and the effects of maternal zinc deficiency on the offspring's health in animal studies.

METHODS

Research articles were retrieved without date restriction from PubMed, Web of Science, ScienceDirect, and Google Scholar databases, as well as reference lists of relevant articles. The search terms used were "zinc deficiency", "maternal zinc deficiency", "epigenetics", and "offspring." Six studies met the eligibility criteria and were reviewed.

RESULTS

All the eligible studies reported maternal zinc deficiency and observed changes in epigenetic markers on the progeny during prenatal and postnatal stages of development. The main epigenetic markers reported were global and gene specific methylation and/ or acetylation. The epigenetic changes led to mortality, disruption in development, and risk of later life diseases.

CONCLUSION

Maternal zinc deficiency is associated with epigenetic modifications in offspring, which induce pathologies and increase the risk of later life diseases. More research and insight into the epigenetic mechanisms could spring up new approaches to combat the associated disease conditions.

Zinc for the prevention and treatment of SARS-CoV-2 and other acute viral respiratory infections: a rapid review

BACKGROUND

The global COVID-19 pandemic has prompted an urgent search for interventions to prevent and treat SARS-CoV-2. Higher risk of infection and adverse outcomes coincide with populations with chronic diseases and elderly who are at risk of zinc deficiency. Through several mechanisms zinc may prevent, reduce severity and duration of symptoms.

METHOD

An a priori protocol was registered with PROSPERO on 27th April 2020 (CRD42020182044). Eight databases (one Chinese) and four clinical trial registries (one Chinese) were searched for randomised and quasi-randomised controlled trials (RCTs), evaluating single or adjunct zinc against placebo or active controls, for prevention and/or treatment of SARS-CoV-2, other coronaviruses or related infections. RR constraints included not searching bibliographies or contacting authors, single reviewers with calibration and second reviewer checking, meta-analyses and quality appraisal of critical and study primary outcomes only and reporting results as they became available.

RESULTS

118 publications of 1,627 records met the inclusion criteria (35 Chinese and 83 English publications), 32 for prevention, 78 for treatment and 8 for both. Four RCTs specific to SARS-CoV-2 are ongoing; two are investigating zinc for prevention and two for treatment. As of 7 July 2020, no results were available. A wide range of zinc forms, including nasal spray/gel, lozenges, liquid, tablets and intramuscular were investigated.

CONCLUSION

Currently, indirect evidence suggests zinc may potentially reduce the risk, duration and severity of SARS-CoV-2 infections, particularly for populations at risk of zinc deficiency including people with chronic disease co-morbidities and older adults. Direct evidence to determine if zinc is effective for either prevention or treatment of SARS-CoV-2 is pending. In the interim, assessing zinc status of people with chronic diseases and older adults, as part of a SARS-CoV-2 clinical work-up, is reasonable as both groups have a higher risk of zinc deficiency/insufficiency and poorer outcomes from SARS-CoV-2.

Rapid review protocol: Zinc for the prevention or treatment of COVID-19 and other coronavirus-related respiratory tract infections

Background

The global COVID-19 pandemic has prompted an urgent search for effective interventions. SARS-CoV-2 mortality/morbidity risk increases with age and for those chronic disease co-morbidities, both of which are associated with lower zinc status, as is the risk of infection.

Methods

Rapid review methods will be applied to a systematic review of zinc for the prevention or treatment of SARS-CoV-2 and viral respiratory tract infections in humans. Included are published studies reporting randomised and quasi-randomised controlled trials that compare zinc intervention to placebo and/or other comparator interventions. English and Chinese language databases will be searched for primary studies of viral respiratory tract infections and clinical trial registries for SARS-CoV-2 infections. Due to concerns about indirectness, studies evaluating non-SARS-CoV-2 coronavirus infections will be rated down by one level, and non-specific or confirmed non-coronavirus viral infections will be rated down by two levels. Review constraints include (1) using Google translate when screening articles published in languages other than English or Chinese and limited translation (2) following calibration, only one reviewer will screen articles, extract data, appraise quality and conduct the analysis, (3) prioritising data extraction and meta-analyses of SARS-CoV-2 studies and critical outcomes of other viral infections, followed by high risk groups and (4) reporting important preliminary findings prior to peer review if necessary.

Discussion

The application of these rapid review methods and broadening the inclusion criteria to include other coronavirus-related viral respiratory tract infections aims to enable a timely evidence appraisal of priority research questions and dissemination of results.

Study registration

PROSPERO CRD42020182044.

Distribution and predictors of 20 toxic and essential metals in the umbilical cord blood of Chinese newborns

Early-life exposure to heavy metals and/or trace metal imbalances can have negative developmental effects. Here we sought to characterize exposure profiles for 20 heavy metals and trace elements in umbilical cord blood plasma and identify demographic predictors of exposure. Twenty metals were measured in cord plasma from 357 Chinese infants using ICP-MS. Relationships between demographic variables and metals were analyzed using generalized linear models and logistic regression. Ten metals (antimony [Sb], cobalt [Co], cesium [Cs], copper [Cu], lead [Pb], molybdenum [Mo], rubidium [Rb], selenium [Se], strontium [Sr], titanium [Ti], zinc [Zn]) were detected in all samples. Season of birth was the strongest predictor of metals in cord blood across analyses. Infants born in the spring had 0.1-0.2 μg L-1 higher logAs and logCo in their cord blood (β [95%CI] = 0.22 [0.01,0.42], p = 0.04; 0.11 [0.01,0.22], p = 0.04), while infants born in the summer had higher Sb, logB, logHg, and logZn (β [95%CI] = 0.74 [0.24,1.24], p = 0.004; 0.11 [0.00,0.21], p = 0.04; 0.29 [0.08,0.49], p = 0.007; 0.18 [0.06,0.31], p = 0.005), compared to those born in fall/winter. Prenatal heavy metal exposure and/or trace metal deficiencies are global concerns because of increasing awareness of downstream developmental effects.

Exposure of cadmium via smoking and drinking water on zinc levels of biological samples of malnutrition pregnant women: A prospective cohort study

In present study, the interaction of a toxic (cadmium) and essential element (zinc) was determined in scalp hair of pregnant and non-pregnant women resident in a rural area of Thraparkar, Pakistan, where malnutrition is prevalent. In the malnourished group (pregnant and nonpregnant women), deficiency of the essential element (zinc) due to malnutrition and exposure of toxic metal (cadmium) via non-branded cigarette smoking and drinking groundwater were carried out. For comparative purposes, scalp hair samples were also collected from pregnant and non-pregnant women, residing in Hyderabad city, consuming municipal treated drinking water and smoking branded cigarette, termed as the reference group. The domestic treated and ground water, as well as the branded and non-branding cigarettes were analysed for cadmium (Cd). Whereas Zinc (Zn) and Cd were determined in scalp hair samples of malnutrioned and reference women. The groundwater indicated 5 to 12 fold higher levels of Cd than the WHO recommended value in drinking water. Whereas the content of Cd in locally made non-branded cigarettes was found to be two fold higher than branded cigarettes. These data indicate that the malnourished pregnant and non-pregnant smokers women group had three to four times higher levels of Cd in their scalp hair samples than those values obtained for reference non smokers. Whereas, the content of Zn in scalp hair samples of the reference women was ∼20% higher than the malnourished group.

Expression of matrix metalloproteinase-9 and its substrate level in patients with premature rupture of membranes

In this study, 30 case of patients with full-term premature membrane rupture and another 30 cases of full-term delivered subject without premature rupture of membranes (PROM) were selected to explore the relationship between premature membrane rupture with matrix metalloproteinase 9 (MMP-9) and its substrate level. Results showed the plasma zinc, MMP-9 in serum and amniotic fluid increased in patients with PROM; their type IV collagen in serum and foetal membrane decreased. Increased Zinc ion concentration results in increased concentration of MMP-9, a zinc-dependent enzyme; the degradation of type IV collagen by MMP-9 might be the potential mechanism of premature rupture of membranes in full-term pregnant women.

Association between Maternal Zinc Status, Dietary Zinc Intake and Pregnancy Complications: A Systematic Review

Adequate zinc stores in the body are extremely important during periods of accelerated growth. However, zinc deficiency is common in developing countries and low maternal circulating zinc concentrations have previously been associated with pregnancy complications. We reviewed current literature assessing circulating zinc and dietary zinc intake during pregnancy and the associations with preeclampsia (PE); spontaneous preterm birth (sPTB); low birthweight (LBW); and gestational diabetes (GDM). Searches of MEDLINE; CINAHL and Scopus databases identified 639 articles and 64 studies were reviewed. In 10 out of 16 studies a difference was reported with respect to circulating zinc between women who gave birth to a LBW infant (≤2500 g) and those who gave birth to an infant of adequate weight (>2500 g), particularly in populations where inadequate zinc intake is prevalent. In 16 of our 33 studies an association was found between hypertensive disorders of pregnancy and circulating zinc; particularly in women with severe PE (blood pressure ≥160/110 mmHg). No association between maternal zinc status and sPTB or GDM was seen; however; direct comparisons between the studies was difficult. Furthermore; only a small number of studies were based on women from populations where there is a high risk of zinc deficiency. Therefore; the link between maternal zinc status and pregnancy success in these populations cannot be established. Future studies should focus on those vulnerable to zinc deficiency and include dietary zinc intake as a measure of zinc status.

Iron and zinc exploitation during bacterial pathogenesis

Ancient bacteria originated from metal-rich environments. Billions of years of evolution directed these tiny single cell creatures to exploit the versatile properties of metals in catalyzing chemical reactions and biological responses. The result is an entire metallome of proteins that use metal co-factors to facilitate key cellular process that range from the production of energy to the replication of DNA. Two key metals in this regard are iron and zinc, both abundant on Earth but not readily accessible in a human host. Instead, pathogenic bacteria must employ clever ways to acquire these metals. In this review we describe the many elegant ways these bacteria mine, regulate, and craft the use of two key metals (iron and zinc) to build a virulence arsenal that challenges even the most sophisticated immune response.

The effect of zinc supplementation on pregnancy outcomes: a double-blind, randomised controlled trial, Egypt

The present randomised controlled trial (RCT) was conducted to evaluate the effect of two regimens of Zn supplementation on pregnancy outcomes in Alexandria, Egypt. Healthy pregnant women aged 20–45 years and having low serum Zn level below the estimated median for the gestational age were eligible to participate in the trial. Of 1055 pregnant women assessed for the eligibility of low serum Zn level, 675 were eligible. These women were randomly assigned to one of the three groups: the Zn alone group (n 225) received a daily dose of 30 mg ZnSO4, the combined group (n 227) received 30 mg ZnSO4 plus multivitamins (B1, B6, D3, C and E) and the control group (n 223) received placebo (270 mg lactose). They were followed up from the time of recruitment till 1 week after delivery. Overall, there was no detectable difference in the mean birth weight between the three groups (mean 2929.12 (SD 330.28), 2922.22 (SD 324.05) and 2938.48 (SD 317.39) g for the placebo, Zn and Zn plus multivitamin groups, respectively, P = 0.88). Both the single and the combined Zn supplements were almost equally effective in reducing second- and third-stage complications (relative risk (RR) 0.43, 95% CI 0.31, 0.60 for the Zn group and RR 0.54, 95% CI 0.40, 0.73 for the combined group). Stillbirth and preterm delivery were significantly lower among the two supplemented groups than the placebo group (P = 0.001). Early neonatal morbidity was also significantly lower in the supplemented groups (RR 0.23, 95% CI 0.15, 0.35 for the Zn group and RR 0.25, 95% CI 0.16, 0.37 for the combined group). Collectively, Zn supplementation was effective in reducing pregnancy complications and early neonatal infection among the Zn-deficient women of the present trial.

The effect of zinc supplementation on pregnancy outcome: a randomized controlled trial

OBJECTIVES

This study aimed to evaluate the impact of prenatal zinc supplementation on pregnancy outcomes.

METHODS

A randomized controlled trial with equal randomization (1:1) was conducted on 540 pregnant women in Rasht, Iran from January 2010 to January 2012. Participants were randomly assigned to receive a daily supplement including 400-µg folic acid and 30-mg ferrous sulfate, with or without 15-mg zinc sulfate from the 16th week of gestation until delivery.

RESULTS

Mean difference of birth weight between the two groups was not significantly different (3262 ± 390 g in the zinc, 3272 ± 403 g in the no-zinc groups) (p = 0.780). There were no significant differences between the two groups in terms of means of head circumference (p = 0.999), length (p = 0.848), and gestational age at birth (p = 0.057) incidences of low birth weight (p = 0.863), macrosomia (p = 0.642), and the Apgar score >7 at 5 min (p = 0.999), incidences of preterm delivery (p = 0.999), pre-eclampsia (p = 0.835), premature rupture of membranes (p = 0.630), and spontaneous abortion (p = 0.772). Abruption of placenta, amnionitis, stillbirth, and intrauterine death were not observed.

CONCLUSION

Based on our findings, 15-mg zinc supplementation daily from 16 weeks of pregnancy until delivery cannot improve pregnancy outcomes.

The Effect of Multi mineral-Vitamin D Supplementation on Pregnancy Outcomes in Pregnant Women at Risk for Pre-eclampsia

Background:

The objective of this study was to determine the favorable effects of multi mineral-Vitamin D supplementation on pregnancy outcomes among women at risk for pre-eclampsia.

Methods:

This randomized double-blind controlled clinical trial was conducted among 46 women at risk for pre-eclampsia at 27 weeks’ gestation with positive roll-over test. Pregnant women were randomly assigned to receive either the multi mineral-Vitamin D supplements (n = 23) or the placebo (n = 23) for 9-week. Multi mineral-Vitamin D supplements were containing 800 mg calcium, 200 mg magnesium, 8 mg zinc, and 400 IU Vitamin D3. Fasting blood samples were taken at baseline and after 9-week intervention to measure related factors. Newborn's outcomes were determined.

Results:

Although no significant difference was seen in newborn's weight and head circumference between the two groups, mean newborns’ length (51.3 ± 1.7 vs. 50.3 ± 1.2 cm, P = 0.03) was significantly higher in multi mineral-Vitamin D group than that in the placebo group. Compared to the placebo, consumption of multi mineral-Vitamin D supplements resulted in increased levels of serum calcium (+0.19 vs. −0.08 mg/dL, P = 0.03), magnesium (+0.15 vs. −0.08 mg/dL, P = 0.03), zinc (+8.25 vs. −21.38 mg/dL, P = 0.001) and Vitamin D (+3.79 vs. −1.37 ng/ml, P = 0.01). In addition, taking multi mineral-Vitamin D supplements favorably influenced systolic blood pressure (SBP) (−1.08 vs. 6.08 mmHg, P = 0.001) and diastolic blood pressure (DBP) (−0.44 vs. 3.05 mmHg, P = 0.02).

Conclusions:

Multi mineral-Vitamin D supplementation for 9-week in pregnant women at risk for pre-eclampsia resulted in increased newborn's length, increased circulating levels of maternal serum calcium, magnesium, zinc and Vitamin D, and led to decreased maternal SBP and DBP.

A review of the impact of dietary intakes in human pregnancy on infant birthweight

Studies assessing maternal dietary intakes and the relationship with birthweight are inconsistent, thus attempting to draw inferences on the role of maternal nutrition in determining the fetal growth trajectory is difficult. The aim of this review is to provide updated evidence from epidemiological and randomized controlled trials on the impact of dietary and supplemental intakes of omega-3 long-chain polyunsaturated fatty acids, zinc, folate, iron, calcium, and vitamin D, as well as dietary patterns, on infant birthweight. A comprehensive review of the literature was undertaken via the electronic databases Pubmed, Cochrane Library, and Medline. Included articles were those published in English, in scholarly journals, and which provided information about diet and nutrition during pregnancy and infant birthweight. There is insufficient evidence for omega-3 fatty acid supplements’ ability to reduce risk of low birthweight (LBW), and more robust evidence from studies supplementing with zinc, calcium, and/or vitamin D needs to be established. Iron supplementation appears to increase birthweight, particularly when there are increases in maternal hemoglobin concentrations in the third trimester. There is limited evidence supporting the use of folic acid supplements to reduce the risk for LBW; however, supplementation may increase birthweight by ~130 g. Consumption of whole foods such as fruit, vegetables, low-fat dairy, and lean meats throughout pregnancy appears beneficial for appropriate birthweight. Intervention studies with an understanding of optimal dietary patterns may provide promising results for both maternal and perinatal health. Outcomes from these studies will help determine what sort of dietary advice could be promoted to women during pregnancy in order to promote the best health for themselves and their baby.

Increased stem cell marker expressions during the peri-implantation period in the rat endometrium: constructive role of exogenous zinc and/or progesterone

Background. The aim of this study is to determine the effects of zinc and/or progesterone via the expression of αvβ5 integrins and Vitronectins and embryonic stem cell markers during the peri-implantation period. Methods. Four experimental groups were organized. All subjects were mated with males of the same strain to induce pregnancy; after 5 days, zinc and/or progesterone were administered. Blood levels of zinc and progesterone were determined on the sixth day and endometrial tissues were obtained in order to evaluate the immunohistochemical expression of integrins and embryonic stem cell markers. Results. The αvβ5 integrin and vitronectin expression increased in the zinc group compared with the control group and no difference in the progesterone group and zinc + progesterone group. Expression of Klf-4, Sox-2, and c-Myc was found to be increased in the zinc group compared to controls, while no difference was determined between the progesterone, zinc + progesterone, and control groups. Distinctively, expression of the embryonic stem cell marker Oct-4 was increased in all of the experimental groups. Conclusions. Expression of αvβ5 integrin, vitronectin, and embryonic stem cell markers might be increased by the administration of zinc. Our results suggest that zinc could be useful in the induction of implantation rates.

Zinc: The Metal of Life

The importance of zinc was 1st reported for Aspergillus niger. It took over 75 y to realize that zinc is also an essential trace element for rats, and an additional 30 y went by before it was recognized that this was also true for humans. The adult body contains about 2 to 3 g of zinc. Zinc is found in organs, tissues, bones, fluids, and cells. It is essential for many physiological functions and plays a significant role in a number of enzyme actions in the living systems. Bioinformatics estimates report that 10% of the human proteome contains zinc-binding sites. Based on its role in such a plethora of cellular components, zinc has diverse biological functions from enzymatic catalysis to playing a crucial role in cellular neuronal systems. Thus, based on the various published studies and reports, it is pertinent to state that zinc is one of the most important essential trace metals in human nutrition and lifestyle. Its deficiency may severely affect the homeostasis of a biological system. This review compiles the role of zinc in prophylaxis/therapeutics and provides current information about its effect on living beings.

Preconception zinc deficiency disrupts postimplantation fetal and placental development in mice

Zinc is an essential nutrient for optimal fertility, but the effects of preconception zinc deficiency on postimplantation development are not known. Female mice were fed a control or a zinc-deficient diet (ZDD) for 4-5 days before ovulation (preconception). Embryonic and/or placental development were evaluated on Days 3.5, 6.5, 10.5, 12.5, and 16.5 of pregnancy. The findings show a decrease in embryo length (31%, Day 10.5; 13%, Day 12.5; 10%, Day 16.5) and weight (23%, Day 16.5) in embryos from mothers fed a ZDD preconception. Zinc deficiency also caused a high incidence of pregnancy loss (46%, Day 10.5; 34%, Day 12.5; 51%, Day 16.5) compared to control (2%, Day 10.5; 7%, Day 12.5; 9%, Day 16.5). ZDD embryos transferred to normal recipients were 38% smaller and implantation rate was only 10% compared to 40% for controls. Trophoblast cell differentiation and implantation on Day 6.5 of pregnancy were compromised by preconception zinc deficiency. On Day 12.5 of pregnancy, placenta weight and area of fetal placenta were decreased 37% and 31%, respectively, by preconception zinc deficiency. Consistent with a smaller fetal placenta, expression of key placental transcripts, including Ar, Esx1, Syna, Tfeb, Dlx3, and Gcm1 mRNA, but not Ctsq mRNA, were decreased 30%-70% in the ZDD group. Preconception zinc deficiency caused 41%-57% of embryos to exhibit delayed or aberrant neural tube development, as examined by light microscopy and magnetic resonance imaging. Collectively, the findings provide evidence for the importance of preconception zinc in promoting optimal fertility and oocyte developmental potential.

The micronutrient levels in the third trimester of pregnancy and assessment of the neonatal outcome: a pilot study

CONTEXT

During pregnancy, an adequate intake of vitamins and minerals is recommended, to prevent the occurrence of adverse effects in the mother and the foetus.

AIM

In our study, we aimed to study the levels of the micronutrients like iron, zinc and copper in the third trimester of pregnancy and to assess the neonatal outcome in them.

MATERIAL AND METHODS

Fifty pregnant women who were aged 20-30 years, who had completed 24 weeks of gestation, who were on regular antenatal checkups, were included. The collected venous blood samples were used for the estimation of haemoglobin, serum ferritin, zinc and copper. They were followed up till their deliveries and the neonatal outcomes were noted. The gestational ages, weight of the babies, the lengths of the babies and their head circumferences and any complications which had occurred during and after the deliveries, were noted in the proforma.

RESULTS

The serum ferritin levels did not significantly correlate with the other study parameters. The zinc levels decreased with an increase in the parity (p<0.05). The copper levels decreased with an increase in the BMI (p<0.05). With an increase in haemoglobin, there was an increase in the levels of zinc and ferritin (p<0.05). With an increase in the parity, there was a decrease in the neonatal birth weight.

CONCLUSION

Our study clearly brought out a correlation between the microminerals such as iron, zinc and copper during late pregnancies. An improvement in the iron status brings out a positive effect on the ferritin and zinc levels, thus indicating better outcomes of the pregnancies.

Acute dietary zinc deficiency before conception compromises oocyte epigenetic programming and disrupts embryonic development

Recent findings show that zinc is an important factor necessary for regulating the meiotic cell cycle and ovulation. However, the role of zinc in promoting oocyte quality and developmental potential is not known. Using an in vivo model of acute dietary zinc deficiency, we show that feeding a zinc deficient diet (ZDD) for 3-5 days before ovulation (preconception) dramatically disrupts oocyte chromatin methylation and preimplantation development. There was a dramatic decrease in histone H3K4 trimethylation and global DNA methylation in zinc deficient oocytes. Moreover, there was a 3-20 fold increase in transcript abundance of repetitive elements (Iap, Line1, Sineb1, Sineb2), but a decrease in Gdf9, Zp3 and Figla mRNA. Only 53% and 8% of mature eggs reached the 2-cell stage after IVF in animals receiving a 3 and 5 days ZDD, respectively, while a 5 day ZDD in vivo reduced the proportion of 2-cells to 49%. In vivo fertilized 2-cell embryos cultured in vitro formed fewer (38%) blastocysts compared to control embryos (74%). Likewise, fewer blastocyst and expanded blastocyst were collected from the reproductive tract of zinc deficient animals on day 3.5 of pregnancy. This could be due to a decrease in Igf2 and H19 mRNA in ZDD blastocyst. Supplementation with a methyl donor (SAM) during IVM restored histone H3K4me3 and doubled the IVF success rate from 17% to 43% in oocytes from zinc deficient animals. Thus, the terminal period of oocyte development is extremely sensitive to perturbation in dietary zinc availability.

The role of minerals in food selection in a black howler monkey (Alouatta pigra) population in Belize following a major hurricane

As plants may contain low levels of some minerals including sodium, copper, and phosphorous, herbivores may become deficient in these nutrients. In 2001, Hurricane Iris hit the Monkey River Forest in Belize causing substantial damage to the food supply of the black howler monkey population (Alouatta pigra) living there. This included an 18-month absence in fruit production and a complete loss of figs that are high in calcium. In this article, we describe the post-hurricane diet of this monkey population and compare the mineral content of food items to each other and to recommendations for non-human primates [NRC 2003]. We also investigate food selection in relation to potentially limiting minerals. Behavioral data from four groups of howlers (2002-2006) and samples of all ingested food items were collected and a sample of 99 plant from 18 food species was analyzed for mineral content. Unexpectedly, the post-hurricane diet contained more mature leaves than new leaves despite the availability of new leaves. Leaves contained higher amounts of minerals than reproductive parts and with the exception of Cecropia peltata stems, plant parts were low in sodium. Cecropia peltata is a pioneer species that grows following habitat disturbance thus the ingestion of these stems may be a potential mechanism to avoid sodium deficiency in this damaged forest. Calcium and zinc were found above recommended values in most food items; however, both positively predicted food selection, which may reflect a difference between their abundance and their bioavailability. However, as mature leaves contained more calcium than other plant parts, their high post-hurricane consumption may also be a response to the absence of figs and the need to find an alternate calcium source. This study highlights how habitat disturbance may affect mineral abundance and the dietary choices of primates.

Maternal zinc intakes and homeostatic adjustments during pregnancy and lactation

Zinc plays critical roles during embryogenesis, fetal growth, and milk secretion, which increase the zinc need for pregnancy and lactation. Increased needs can be met by increasing the dietary zinc intake, along with making homeostatic adjustments in zinc utilization. Potential homeostatic adjustments include changes in circulating zinc, increased zinc absorption, decreased zinc losses, and changes in whole body zinc kinetics. Although severe zinc deficiency during pregnancy has devastating effects, systematic reviews and meta-analysis of the effect of maternal zinc supplementation on pregnancy outcomes have consistently shown a limited benefit. We hypothesize, therefore, that zinc homeostatic adjustments during pregnancy and lactation improve zinc utilization sufficiently to provide the increased zinc needs in these stages and, therefore, mitigate immediate detrimental effects due to a low zinc intake. The specific questions addressed are the following: How is zinc utilization altered during pregnancy and lactation? Are those homeostatic adjustments influenced by maternal zinc status, dietary zinc, or zinc supplementation? These questions are addressed by critically reviewing results from published human studies on zinc homeostasis during pregnancy and lactation carried out in different populations worldwide.

Relationship between Low Birth Weight Neonate and Maternal Serum Zinc Concentration

BACKGROUND

Zinc deficiency can lead to clinically relevant disturbances in tissue functions and particularly important for birth weight of neonates. The aim of this study was to determine the relationship between serum zinc in pregnant women and the incidence of low birth weight (<2500 g) in their newborns.

METHODS

This case-control study was done on women who delivered low birth weight infants (Cases), and normal birth weight infants (Controls). Blood samples got in all women within 5 minutes of delivery, and assessed the concentration of zinc using electrothermal atomic absorption spectrometry. Serum concentration of zinc was compared.

RESULTS

One hundred and seventeen mothers were enrolled, of them, 65 cases were low birth weight infants (1845±472 g) and 52 were controls (3166± 435 g). Mothers in the case and control groups did not differ in age, body mass index, and socioeconomic or demographic factors. Maternal zinc concentration differed between cases and controls; 753.34±15 µg/l vs. 654.76±12 µg/l respectively. Maternal zinc differed between premature and full term deliveries.

CONCLUSION

Maternal zinc concentration was shown to affect birth weight and prematurity.

Impact of maternal zinc status on fetal growth in an Iranian pregnant population

BACKGROUND

To evaluate the impact of mild to moderate maternal zinc deficiency on birth weight of offsprings in a group of Iranian pregnant population.

MATERIALS AND METHODS

One hundred forty pregnant subjects with no history of medical complications during pregnancy and without any inter-current illness enrolled in the study. Serum zinc concentration, ferritin, hemoglobin, iron, and total iron binding capacity (TIBC) were measured at the time of delivery. The receiver operator characteristic (ROC) curve analysis used to determine plasma zinc cutoff value for comparison.

RESULTS

Of 140 live neonates, 30% were below 2500 g. Mean serum zinc concentration was 56.60 ± 17.91 μg/dl which indicated mild to moderate zinc deficiency. None of the subjects were anemic. There was an inverse statistically significant relationship between maternal serum zinc concentration and neonatal birth weight.

CONCLUSION

In this group of Iranian pregnant subjects with mild to moderate zinc deficiency, we observed no relationship between low maternal zinc status and low birth weight infants.

Prevalence of prenatal zinc deficiency and its association with socio-demographic, dietary and health care related factors in rural Sidama, Southern Ethiopia: a cross-sectional study

Background

Several studies witnessed that prenatal zinc deficiency (ZD) predisposes to diverse pregnancy complications. However, scientific evidences on the determinants of prenatal ZD are scanty and inconclusive. The purpose of the present study was to assess the prevalence and determinants of prenatal ZD in Sidama zone, Southern Ethiopia.

Methods

A community based, cross-sectional study was conducted in Sidama zone in January and February 2011. Randomly selected 700 pregnant women were included in the study. Data on potential determinants of ZD were gathered using a structured questionnaire. Serum zinc concentration was measured using Atomic Absorption Spectrometry. Statistical analysis was done using logistic regression and linear regression.

Results

The mean serum zinc concentration was 52.4 (+/-9.9) μg/dl (95% CI: 51.6-53.1 μg/dl). About 53.0% (95% CI: 49.3-56.7%) of the subjects were zinc deficient. The majority of the explained variability of serum zinc was due to dietary factors like household food insecurity level, dietary diversity and consumption of animal source foods. The risk of ZD was 1.65 (95% CI: 1.02-2.67) times higher among women from maize staple diet category compared to Enset staple diet category. Compared to pregnant women aged 15-24 years, those aged 25-34 and 35-49 years had 1.57 (95% CI: 1.04-2.34) and 2.18 (95% CI: 1.25-3.63) times higher risk of ZD, respectively. Women devoid of self income had 1.74 (95% CI: 1.11-2.74) time increased risk than their counterparts. Maternal education was positively associated to zinc status. Grand multiparas were 1.74 (95% CI: 1.09-3.23) times more likely to be zinc deficient than nulliparas. Frequency of coffee intake was negatively association to serum zinc level. Positive association was noted between serum zinc and hemoglobin concentrations. Altitude, history of iron supplementation, maternal workload, physical access to health service, antenatal care and nutrition education were not associated to zinc status.

Conclusion

ZD is of public health concern in the area. The problem must be combated through a combination of short, medium and long-term strategies. This includes the use of household based phytate reduction food processing techniques, agricultural based approaches and livelihood promotion strategies.

Maternal iron and zinc supplementation during pregnancy affects body weight and iron status in rat pups at weaning

Pregnant women worldwide are frequently iron (Fe) and zinc (Zn) deficient. Therefore, cosupplementation with Fe and Zn during pregnancy is common. Although Fe supplementation programs are successful, studies suggest that Zn supplementation negatively affects maternal Fe metabolism. However, little is known about the effects of maternal Fe or Zn supplementation on Fe metabolism in the offspring. We developed a rat model to investigate if Fe and/or Zn supplementation during pregnancy affects regulation of nonheme Fe absorption and Fe status in offspring and if these effects are dependent upon maternal Fe and Zn status at conception. Control (C; fed a Fe- and Zn-adequate diet; 75 and 25 μg/g, respectively) or Fe- and Zn-deficient (D; fed a Fe- and Zn-deficient diet; 12 and 10 μg/g, respectively) rats were supplemented with Fe (27 mg/wk), Zn (4.5 mg/wk), Fe+Zn (27 mg Fe, 4.5 mg Zn/wk), or placebo throughout pregnancy. At postnatal d 21, body weight (BW), hemoglobin (Hb), hematocrit (Hct), liver and intestine Fe concentration, liver hepcidin, and intestine Fe transporter expression were determined in pups. Zn supplementation of C dams decreased pup BW (P < 0.0001), whereas it increased pup BW in D dams (P < 0.0001). Zn supplementation of C dams did not affect Hb and Hct in pups but increased the liver Fe concentration (P = 0.0002). However, Zn supplementation of D dams decreased hepcidin expression in their offspring (P < 0.0001). In C dams, Fe and Fe+Zn supplementation decreased ferroportin levels in pup intestine compared with pups from unsupplemented dams (P < 0.05). In conclusion, Zn supplementation of dams with adequate Fe and Zn status increases offspring liver Fe concentration and postnatally compromises BW. Therefore, potential adverse effects of Zn supplementation should be evaluated.

Effect of nutrient deficiencies on in vitro Th1 and Th2 cytokine response of peripheral blood mononuclear cells to Plasmodium falciparum infection

Background

An appropriate balance between pro-inflammatory and anti-inflammatory cytokines that mediate innate and adaptive immune responses is required for effective protection against human malaria and to avoid immunopathology. In malaria endemic countries, this immunological balance may be influenced by micronutrient deficiencies.

Methods

Peripheral blood mononuclear cells from Tanzanian preschool children were stimulated in vitro with Plasmodium falciparum-parasitized red blood cells to determine T-cell responses to malaria under different conditions of nutrient deficiencies and malaria status.

Results

The data obtained indicate that zinc deficiency is associated with an increase in TNF response by 37%; 95% CI: 14% to 118% and IFN-γ response by 74%; 95% CI: 24% to 297%. Magnesium deficiency, on the other hand, was associated with an increase in production of IL-13 by 80%; 95% CI: 31% to 371% and a reduction in IFN-γ production. These results reflect a shift in cytokine profile to a more type I cytokine profile and cell-cell mediated responses in zinc deficiency and a type II response in magnesium deficiency. The data also reveal a non-specific decrease in cytokine production in children due to iron deficiency anaemia that is largely associated with malaria infection status.

Conclusions

The pathological sequels of malaria potentially depend more on the balance between type I and type II cytokine responses than on absolute suppression of these cytokines and this balance may be influenced by a combination of micronutrient deficiencies and malaria status.

Role of nutrients in the development of neonatal immune response

Nutrients exert unique regulatory effects in the perinatal period that mold the developing immune system. The interactions of micronutrients and microbial and environmental antigens condition the post-birth maturation of the immune system, influencing reactions to allergens, fostering tolerance towards the emerging gastrointestinal flora and ingested antigens, and defining patterns of host defense against potential pathogens. The shared molecular structures that are present on microbes or certain plants, but not expressed by human cells, are recognized by neonatal innate immune receptors. Exposure to these activators in the environment through dietary intake in early life can modify the immune response to allergens and prime the adaptive immune response towards pathogens that express the corresponding molecular structures.

The plausibility of maternal nutritional status being a contributing factor to the risk for fetal alcohol spectrum disorders: the potential influence of zinc status as an example

There is increasing evidence that human pregnancy outcome can be significantly compromised by suboptimal maternal nutritional status. Poor diet results in a maternal-fetal environment in which the teratogenicity of other insults such as alcohol might be amplified. As an example, there is evidence that zinc (Zn) can interact with maternal alcohol exposure to influence the risk for fetal alcohol spectrum disorders (FASD). Studies with experimental animals have shown that the teratogenicity of alcohol is increased under conditions of Zn deficiency, whereas its teratogenicity is lessened when animals are given Zn-supplemented diets or Zn injections before the alcohol exposure. Alcohol can precipitate an acute-phase response, resulting in a subsequent increase in maternal liver metallothionein, which can sequester Zn and lead to decreased Zn transfer to the fetus. Importantly, the teratogenicity of acute alcohol exposure is reduced in metallothionein knockout mice, which can have improved Zn transfer to the conceptus relative to wild-type mice. Consistent with the above, Zn status has been reported to be low in alcoholic women at delivery. Preliminary data from two basic science and clinical nutritional studies that are ongoing as part of the international Collaborative Initiative on Fetal Alcohol Spectrum Disorders support the potential role of Zn, among other nutritional factors, relative to risk for FASD. Importantly, the nutrient levels being examined in these studies are relevant to general clinical populations and represent suboptimal levels rather than severe deficiencies. These data suggest that moderate deficiencies in single nutrients can act as permissive factors for FASD, and that adequate nutritional status or intervention through supplementation may provide protection from some of the adverse effects of prenatal alcohol exposure.

Choice of environmental components for a longitudinal birth cohort study

Various aspects of the environment of the mother and child may have major influences on the health and development of the child. Long-term influences can even affect chronic diseases of adulthood. Here we describe the major psychosocial and physical environmental factors that should be measured in longitudinal birth cohort studies.

Role of nutrition in the development of the fetal cardiovascular system

Emerging evidence demonstrates that heart disease may originate during fetal development. This review will focus on the role of maternal nutrition in the development of the fetal cardiovascular system. Emphasis will be placed upon the concept that nutritional inadequacies during gestation may be major programming stimuli that alter fetal cardiac, as well as vascular, physiology and predispose an individual to cardiovascular abnormalities in postnatal life. It is hypothesized that this research area will yield new information, resulting in improved fetal nutrition, growth and development through efficient maternal nutrition before and during pregnancy and will form the basis for nutritional strategies for the primary prevention of cardiovascular disease.

Zinc supplementation reduces iron absorption through age-dependent changes in small intestine iron transporter expression in suckling rat pups

Zinc (Zn) supplementation negatively affects iron (Fe) absorption; however, the molecular mechanisms are not understood. We determined effects of Zn supplementation during mid- and late infancy on intestinal Fe transport mechanisms using a suckling rat model. Suckled rat pups were supplemented with 0 (control), 300 (low), or 750 (high) microg Zn/d until weaning at postnatal day (PN) 20. At mid-(PN10) and late (PN20) infancy, tissue Fe distribution, Fe absorption, intestine DMT1, ferroportin-1 (FPN) and hephaestin expression, and localization and liver hepcidin expression were measured. During early infancy, DMT1 and FPN were localized intracellularly. Negative effects of Zn supplementation on Fe absorption were associated with increased small intestine Fe retention, decreased hephaestin, and increased FPN expression. During late infancy, both DMT1 and FPN were appropriately localized to the apical and basolateral membrane, respectively, and negative effects of Zn supplementation on Fe absorption were absent. Although FPN protein level was lower in Zn-supplemented pups, hephaestin protein level was increased, which may have facilitated enhanced Fe efflux. These results indicate that Zn supplementation reduced Fe absorption during early infancy as a consequence of increased intestinal Fe retention due to reduced hephaestin levels. These effects were age-dependent, further demonstrating that Fe transport regulation is not fully developed until weaning, which may have important implications regarding the safety and efficacy of Zn supplementation programs for infants.

Zinc deficiency in pregnancy and fetal outcome

Maternal zinc deficiency during pregnancy has been related to adverse effects on progeny, and there are data showing that mild to moderate zinc deficiency (as assessed by available indicators) is quite common in the developing world. Observational data relating zinc deficiency to adverse fetal outcome have produced conflicting results, mainly because of the lack of a valid indicator of zinc deficiency in pregnancy. Studies of human pregnancy and zinc supplementation, including those from developing countries, have failed to document a consistent beneficial effect on fetal growth, duration of gestation, and early neonatal survival. Preliminary results from unpublished studies in developing countries have also proven to be discouraging. However, recent data and some preliminary findings indicate a beneficial effect of maternal zinc supplementation on neonatal immune status and infant morbidity from infectious diseases, and there is also preliminary evidence that, zinc supplementation may prevent congenital malformations (cleft lip/palate). With respect to neurobehavioral development, the evidence is conflicting, with only one study reporting a positive outcome. More research is required to assess the benefits of the large-scale introduction of zinc supplementation during pregnancy on congenital malformations, immune functions, neurobehavior, and overall neonatal survival in countries where zinc deficiency is a problem. Currently available information does not support the routine use of zinc supplementation to improve pregnancy outcome.

[Zinc and pregnancy]

Zinc, an essential trace element, plays a critical role in normal growth and development, cellular integrity and many biological functions, including protein synthesis and nucleic acid metabolism. Since all these are involved in cell division and growth, zinc is believed to be important for foetal growth and development. Zinc requirement is increased during pregnancy but the lack of a valid indicator precludes a true estimate of zinc deficiency in pregnancy even in developed countries. This review examines the possibility that a gestational deficiency of zinc can adversely affect the pregnancy outcome. Preliminary human data suggest a beneficial effect of prenatal zinc supplementation trials in particular on infant's neurobehavioral development. In the light of the currently available information, zinc supplementation at therapeutic load (30 mg/day) as it is proposed for the treatment of hormonal skin disorders to adolescents, cannot be toxic.

Maternal micronutrients and fetal outcome

Maternal micronutrient deficiency has been related to adverse fetal effects. It is believed that micronutrient supplementation during pregnancy may improve fetal and neonatal outcome. Despite biological plausibility, the evidence base for individual micronutrient benefit on neonatal morbidity, mortality, growth and development is patchy and often contradictory, except for the role of folic acid in prevention of neural tube defects. Single micronutrient supplementation interventions have not been shown to consistently affect size at birth or duration of gestation. Sound evidence is generally lacking that micronutrient supplementation can reduce infection-related adverse pregnancy outcomes. However, preliminary data suggests that antenatal zinc supplements may cause reduction in later diarrheal and infectious morbidity in infants. The evidence linking maternal micronutrient deficiency to children's cognitive and motor functioning also lacks a clear consensus except for iodine in endemic areas. There is a pressing need for good quality randomized controlled trials evaluating food based and multiple micronutrient interventions in pregnancy and preconceptually. Future studies should also evaluate the effect on body composition and metabolism along with the functional consequences.

Zinc and the risk for infectious disease

Zinc is an essential micronutrient for human growth, development, and immune function. Zinc deficiency impairs overall immune function and resistance to infection. Mild to moderate zinc deficiency can be best detected through a positive response to supplementation trials. Zinc supplementation has been shown to have a positive effect on the incidence of diarrhea (18% reduction, 95% CI: 7-28%) and pneumonia (41% reduction, 95% CI: 17-59%), and might lead to a decrease in the incidence of malaria. Zinc has also proven to decrease the duration of diarrhea by 15% (95% CI: 5-24%). Maternal zinc supplementation may lead to a decrease in infant infections. Studies assessing the role of zinc supplementation among persons with HIV, tuberculosis, and the common cold have not been conclusive. Two studies have shown zinc supplementation to decrease child mortality by more than 50%. Zinc clearly has an important role in infant and childhood infectious diseases; programs to increase the intake of zinc among deficient populations are needed.

Histochemical and histofluorescence tracing of chelatable zinc in the developing mouse

Zinc is an essential element in mammalian development. However, little is known about concentrations of zinc in specific regions/organs in the embryo. We have employed selenite autometallography (AMG) and TSQ histofluoroscence to detect histochemically reactive (chelatable) zinc in whole midsagittal embryos and sections from neonatal mice. Chelatable zinc exhibited a broad distribution, being particularly localized to rapidly proliferating tissues, such as skin and gastrointestinal epithelium. Zinc was also observed in various types of tissues such as bone and liver. In the perinatal central nervous system, zinc was present almost exclusively in choroid plexus. The two methods used demonstrated generally similar distributions with some exceptions, e.g., in liver and blood. The ubiquity of zinc in the embryo, particularly in rapidly proliferating tissues, suggests a widespread role in fetal physiology.

Effects of a combined micronutrient supplementation on maternal biological status and newborn anthropometrics measurements: a randomized double-blind, placebo-controlled trial in apparently healthy pregnant women

OBJECTIVE

To investigate the possible beneficial effects of a micronutrient supplementation to apparently healthy pregnant women on maternal biological status and new born anthropometric characteristics.

SETTING

Departments of Obstetric of the University Hospital of Grenoble (France) and Lyon (France), Laboratoire of Biology of Oxidative Stress, UFR de Pharmacie. Grenoble (France).

STUDY DESIGN

Double-blind, randomized placebo-controlled intervention trial.

SUBJECTS

A total of 100 apparently healthy pregnant women were recruited at 14+/-2 weeks of gestation to delivery. At the end, they were 65 women to follow out the study.

INTERVENTIONS

Daily consumption over gestation of a micronutrients supplement or placebo.

MAIN OUTCOME MEASURES

Plasma micronutrient levels and oxidative stress parameters were measured in mothers at 14 and 38 weeks of gestation. New born's anthropometric characteristics were measured at delivery.

RESULTS

In the supplemented group, folic acid, vitamin C, E, B2, B6 and beta-carotene levels were higher than in the placebo group. Oxidative stress parameters were not different between the groups. Birth weights were increased by 10% and the number of low newborn weights (<2700 g) decreased significantly when the mother received the supplementation. Maternal plasma Zn levels were positively correlated to the newborn heights.

CONCLUSION

A regular intake of a micronutrient supplement at nutritional dose may be sufficient to improve micronutrient status of apparently healthy pregnant women and could prevent low birth weight of newborn.

Micronutrients and fetal growth

Fetal undernutrition affects large numbers of infants in developing countries, with adverse consequences for their immediate survival and lifelong health. It manifests as intrauterine growth retardation (IUGR), defined as birth weight <10th percentile, which probably underestimates the number failing to achieve full growth potential. Birth weight is a crude measure of the dynamic process of fetal growth and does not capture effects of fetal undernutrition on body composition and the development of specific tissues. The link between maternal nutrition and fetal nutrition is indirect. The fetus is nourished by a complex supply line that includes the mother's diet and absorption, endocrine status and metabolism, cardiovascular adaptations to pregnancy and placental function. Micronutrients are essential for growth, and maternal micronutrient deficiency, frequently multiple in developing countries, may be an important cause of IUGR. Supplementation of undernourished mothers with micronutrients has several benefits but there is little hard evidence of improved fetal growth. However, this has been inadequately tested. Most trials have only used single micronutrients and many were inconclusive because of methodological problems. Several food-based studies (some uncontrolled) suggest benefits from improving maternal dietary quality with micronutrient-dense foods. One trial of a multivitamin supplement (HIV-positive mothers, Tanzania) showed increased birth weight and fewer fetal deaths. Well-conducted randomized controlled trials of adequate sample size and including measures of effectiveness are needed in populations at high risk of micronutrient deficiency and IUGR and should include food-based interventions and better measurements of fetal growth, maternal metabolism, and long-term outcomes in the offspring.

The plausibility of micronutrient deficiencies being a significant contributing factor to the occurrence of pregnancy complications

Numerous studies support the concept that a major cause of pregnancy complications can be suboptimal embryonic and fetal nutrition. Although the negative effects of diets low in energy on pregnancy outcome are well documented, less clear are the effects of diets that are low in one or more essential micronutrients. However, several observational and intervention studies suggest that diets low in essential vitamins and minerals can pose a significant reproductive risk in diverse human populations. Although maternal nutritional deficiencies typically occur as a result of low dietary intakes of essential nutrients, nutritional deficiencies at the level of the conceptus can arise through multiple mechanisms. Evidence from experimental animals supports the concept that in addition to primary deficiencies, secondary embryonic and fetal nutritional deficiencies can be caused by diverse factors including genetics, maternal disease, toxicant insults and physiological stressors that can trigger a maternal acute phase response. These secondary responses may be significant contributors to the occurrence of birth defects. An implication of the above is that the frequency and severity of pregnancy complications may be reduced through an improvement in the micronutrient status of the mother.

The need for maternal zinc supplementation in developing countries: an unresolved issue

Maternal zinc deficiency during pregnancy has been related to adverse pregnancy outcomes. Most studies in which pregnant women have been supplemented with zinc to examine effects on pregnancy outcome have been carried out in industrialized countries and the results have been inconclusive. This review discusses preliminary findings of eight randomized, controlled intervention trials performed recently in less-developed countries. It is based on evidence presented by investigators and discussed during a workshop held in Wageningen, The Netherlands in June 2001. Preliminary findings from these studies indicate maternal zinc supplementation has a beneficial effect on neonatal immune status, early neonatal morbidity and infant infections. With respect to labor and delivery complications, gestational age at birth, maternal zinc status and health and fetal neurobehavioral development, evidence is conflicting and more research is required. Data currently available do not support the hypothesis that maternal zinc supplementation promotes intrauterine growth. Thus despite the emerging evidence for a positive effect of zinc on some outcomes of pregnancy, the workshop concluded that the full results of studies carried out need to be known and that more research is required to determine the benefits of large-scale introduction of zinc supplementation of pregnant women in less-developed countries.

Zinc supplementation during pregnancy and effects on mental development and behaviour of infants: a follow-up study

BACKGROUND

Zinc deficiency is widely prevalent in developing countries. Zinc supplements given to Bangladeshi pregnant women have been shown to reduce infants' infectious disease morbidity. We assessed these infants at age 13 months to establish the effect of antenatal zinc supplementation on infant development and behaviour.

METHODS

The study originally consisted of 559 pregnant women who were randomly allocated to zinc (30 mg daily) or placebo (cellulose) from 4 months' gestation to delivery. The effect of zinc supplementation on pregnancy outcome and on infant growth and morbidity in the first 6 months was assessed. We then randomly selected a subsample of 168 infants from 383 who completed the study at 6 months. When babies in this subsample reached age 13 months, we assessed mental development with Bayley scales of infant development-II, rated behaviour on a modified version of Wolke's scales, and measured weight and height.

FINDINGS

When we controlled for differences between tested and non-tested participants, infants in the placebo group had higher scores on mental development index (regression coefficient=3.3, SE 1.6, 95% CI 0.2-6.5, p=0.04) and psychomotor development index (5.1, 2.4, 0.2-9.9, p=0.04) than those in the zinc-supplemented group. Zinc supplementation had no significant effect on behaviour or growth. The children's nutritional status was poor, and weight-for-age at testing was strongly related to developmental levels, which accounted for some of the treatment effect.

INTERPRETATION

Prenatal supplementation with zinc alone in poor women from Bangladesh does not seem to confer benefit on infants' mental development. Such treatment should be considered with caution.