Estimating the global prevalence of zinc deficiency: results based on zinc availability in national food supplies and the prevalence of stunting

Multiple-micronutrient supplementation for women during pregnancy

BACKGROUND

Multiple-micronutrient (MMN) deficiencies often coexist among women of reproductive age in low- to middle-income countries. They are exacerbated in pregnancy due to the increased demands, leading to potentially adverse effects on the mother and developing fetus. Though supplementation with MMNs has been recommended earlier because of the evidence of impact on pregnancy outcomes, a consensus is yet to be reached regarding the replacement of iron and folic acid supplementation with MMNs. Since the last update of this Cochrane review, evidence from a few large trials has recently been made available, the inclusion of which is critical to inform policy.

OBJECTIVES

To evaluate the benefits of oral multiple-micronutrient supplementation during pregnancy on maternal, fetal and infant health outcomes.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (11 March 2015) and reference lists of retrieved articles and key reviews. We also contacted experts in the field for additional and ongoing trials.

SELECTION CRITERIA

All prospective randomised controlled trials evaluating MMN supplementation during pregnancy and its effects on the pregnancy outcome were eligible, irrespective of language or the publication status of the trials. We included cluster-randomised trials, but quasi-randomised trials were excluded.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion and risk of bias, extracted data and checked them for accuracy. The quality of the evidence was assessed using the GRADE approach.

MAIN RESULTS

Nineteen trials (involving 138,538 women) were identified as eligible for inclusion in this review but only 17 trials (involving 137,791 women) contributed data to the review. Fifteen of these 17 trials were carried out in low and middle-income countries and compared MMN supplements with iron and folic acid versus iron with or without folic acid. Two trials carried out in the UK compared MMN with a placebo. MMN with iron and folic acid versus iron, with or without folic acid (15 trials): MMN resulted in a significant decrease in the number of newborn infants identified as low birthweight (LBW) (risk ratio (RR) 0.88, 95% confidence interval (CI) 0.85 to 0.91; high-quality evidence) or small-for-gestational age (SGA) (average RR 0.90, 95% CI 0.83 to 0.97; moderate-quality evidence), and a reduced rate of stillbirth (RR 0.91, 95% CI 0.85 to 0.98; high-quality evidence). No significant differences were shown for other maternal and pregnancy outcomes: preterm births (RR 0.96, 95% CI 0.89 to 1.03; high-quality evidence), maternal anaemia in the third trimester (RR 0.97, 95% CI 0.86 to 1.10), miscarriage (RR 0.89, 95% CI 0.78 to 1.01), maternal mortality (RR 0.97, 95% CI 0.63 to 1.48), perinatal mortality (RR 0.97, 95% CI 0.84 to 1.12; high-quality evidence), neonatal mortality (RR 0.98, 95% CI 0.90 to 1.07; high -quality evidence), or risk of delivery via a caesarean section (RR 1.03; 95% CI 0.75 to 1.43).A number of prespecified, clinically important outcomes could not be assessed due to insufficient or non-available data. Single trials reported results for: very preterm birth < 34 weeks, macrosomia, side-effects of supplements, nutritional status of children, and congenital anomalies including neural tube defects and neurodevelopmental outcome: Bayley Scales of Infant Development (BSID) scores. None of these trials reported pre-eclampsia, placental abruption, premature rupture of membranes, cost of supplementation, and maternal well-being or satisfaction.When assessed according to GRADE criteria, the quality of evidence for the review's primary outcomes overall was good. Pooled results for primary outcomes were based on multiple trials with large sample sizes and precise estimates. The following outcomes were graded to be as of high quality: preterm birth, LBW, perinatal mortality, stillbirth and neonatal mortality. The outcome of SGA was graded to be of moderate quality, with evidence downgraded by one for funnel plot asymmetry and potential publication bias.We carried out sensitivity analysis excluding trials with high levels of sample attrition (> 20%); results were consistent with the main analysis. We explored heterogeneity through subgroup analysis by maternal height and body mass index (BMI), timing of supplementation and dose of iron. Subgroup differences were observed for maternal BMI and timing of supplementation for the outcome preterm birth, with significant findings among women with low BMI and with earlier initiation of supplementation in the prenatal period. Subgroup differences were also observed for maternal BMI, maternal height and dose of iron for the outcome SGA, indicating a significant impact among women with higher maternal BMI and height, and with MMN supplement containing 30 mg of iron versus control receiving 60 mg of iron. The findings between subgroups for other primary outcomes were inconclusive. MMN versus placebo (two trials): A single trial in the UK found no clear differences between groups for preterm birth, SGA, LBW or maternal anaemia in the third trimester. A second trial reported the number of women with pre-eclampsia; there was no evidence of a difference between groups. Other outcomes were not reported.

AUTHORS' CONCLUSIONS

Our findings support the effect of MMN supplements with iron and folic acid in improving birth outcomes. The findings, consistently observed in several systematic evaluations of evidence, provide a strong basis to guide the replacement of iron and folic acid with MMN supplements containing iron and folic acid for pregnant women in developing countries where MMN deficiencies are common among women of reproductive age. Efforts should be focused on the integration of this intervention in maternal nutrition and antenatal care programs in developing countries.

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.

Association between low dietary zinc and hyperuricaemia in middle-aged and older males in China: a cross-sectional study

OBJECTIVE

To examine the associations between dietary zinc intake and hyperuricaemia.

DESIGN

Cross-sectional study.

SETTING

This study was conducted in a health examination centre of China.

PARTICIPANTS

A total of 5168 middle-aged and older participants (aged 40 years or above) (2697 men and 2471 women) were included.

OUTCOME MEASURES

Dietary zinc intake was assessed using a validated semiquantitative food frequency questionnaire. Hyperuricaemia was defined as uric acid ≥416 µmol/L for males and ≥360 µmol/L for females.

RESULTS

For males, the prevalence of hyperuricaemia was 22.9%. After adjusting for age, body mass index (BMI) and energy intake, the ORs were 0.68 (95% CI 0.45 to 0.92) in the second quintile, 0.63 (95% CI 0.45 to 0.89) in the third quintile, 0.68 (95% CI 0.46 to 1.00) in the fourth quintile and 0.55 (95% CI 0.35 to 0.87) in the fifth quintile comparing the lowest quintile of Zn intake, respectively (p for trend=0.03). In the multivariable adjusted model, the relative odds of hyperuricaemia were significantly decreased by 0.71 times in the second quintile of zinc intake (OR 0.71, 95% CI 0.52 to 0.98), 0.64 times in the third quintile (OR 0.65, 95% CI 0.44 to 0.94) and 0.55 times in the fifth quintile (OR 0.56, 95% CI 0.32 to 0.97) compared with those in the lowest quintile, and p for trend was 0.064. For females, the prevalence of hyperuricaemia was 10.0%, and unadjusted, minimally adjusted as well as multivariable adjusted ORs all suggested no significant association between dietary zinc intake and hyperuricaemia.

CONCLUSIONS

The findings of this cross-sectional study indicated that dietary zinc intake was inversely associated with hyperuricaemia in middle-aged and older males, but not in females. The association was significant after considering the influence of age, BMI and energy intake, and after that, minimum adjustment remained independent of further confounding factors such as vitamin C intake, alcohol drinking status and nutrient supplementation.

Effect of increased concentrations of atmospheric carbon dioxide on the global threat of zinc deficiency: a modelling study

BACKGROUND

Increasing concentrations of atmospheric carbon dioxide (CO2) lower the content of zinc and other nutrients in important food crops. Zinc deficiency is currently responsible for large burdens of disease globally, and the populations who are at highest risk of zinc deficiency also receive most of their dietary zinc from crops. By modelling dietary intake of bioavailable zinc for the populations of 188 countries under both an ambient CO2 and elevated CO2 scenario, we sought to estimate the effect of anthropogenic CO2 emissions on the global risk of zinc deficiency.

METHODS

We estimated per capita per day bioavailable intake of zinc for the populations of 188 countries at ambient CO2 concentrations (375-384 ppm) using food balance sheet data for 2003-07 from the Food and Agriculture Organization. We then used previously published data from free air CO2 enrichment and open-top chamber experiments to model zinc intake at elevated CO2 concentrations (550 ppm, which is the concentration expected by 2050). Estimates developed by the International Zinc Nutrition Consultative Group were used for country-specific theoretical mean daily per-capita physiological requirements for zinc. Finally, we used these data on zinc bioavailability and population-weighted estimated average zinc requirements to estimate the risk of inadequate zinc intake among the populations of the different nations under the two scenarios (ambient and elevated CO2). The difference between the population at risk at elevated and ambient CO2 concentrations (ie, population at new risk of zinc deficiency) was our measure of impact.

FINDINGS

The total number of people estimated to be placed at new risk of zinc deficiency by 2050 was 138 million (95% CI 120-156). The people likely to be most affected live in Africa and South Asia, with nearly 48 million (32-63) residing in India alone. Global maps of increased risk show significant heterogeneity.

INTERPRETATION

Our results indicate that one heretofore unquantified human health effect associated with anthropogenic CO2 emissions will be a significant increase in the human population at risk of zinc deficiency. Our country-specific findings can be used to help guide interventions aimed at reducing this vulnerability.

FUNDING

Bill & Melinda Gates Foundation, Winslow Foundation.

Effect of increased concentrations of atmospheric carbon dioxide on the global threat of zinc deficiency: a modelling study

BACKGROUND

Increasing concentrations of atmospheric carbon dioxide (CO2) lower the content of zinc and other nutrients in important food crops. Zinc deficiency is currently responsible for large burdens of disease globally, and the populations who are at highest risk of zinc deficiency also receive most of their dietary zinc from crops. By modelling dietary intake of bioavailable zinc for the populations of 188 countries under both an ambient CO2 and elevated CO2 scenario, we sought to estimate the effect of anthropogenic CO2 emissions on the global risk of zinc deficiency.

METHODS

We estimated per capita per day bioavailable intake of zinc for the populations of 188 countries at ambient CO2 concentrations (375-384 ppm) using food balance sheet data for 2003-07 from the Food and Agriculture Organization. We then used previously published data from free air CO2 enrichment and open-top chamber experiments to model zinc intake at elevated CO2 concentrations (550 ppm, which is the concentration expected by 2050). Estimates developed by the International Zinc Nutrition Consultative Group were used for country-specific theoretical mean daily per-capita physiological requirements for zinc. Finally, we used these data on zinc bioavailability and population-weighted estimated average zinc requirements to estimate the risk of inadequate zinc intake among the populations of the different nations under the two scenarios (ambient and elevated CO2). The difference between the population at risk at elevated and ambient CO2 concentrations (ie, population at new risk of zinc deficiency) was our measure of impact.

FINDINGS

The total number of people estimated to be placed at new risk of zinc deficiency by 2050 was 138 million (95% CI 120-156). The people likely to be most affected live in Africa and South Asia, with nearly 48 million (32-63) residing in India alone. Global maps of increased risk show significant heterogeneity.

INTERPRETATION

Our results indicate that one heretofore unquantified human health effect associated with anthropogenic CO2 emissions will be a significant increase in the human population at risk of zinc deficiency. Our country-specific findings can be used to help guide interventions aimed at reducing this vulnerability.

FUNDING

Bill & Melinda Gates Foundation, Winslow Foundation.

Use of Optimization Modeling for Selecting National Micronutrient Intervention Strategies

Vitamin and mineral (micronutrient [MN]) deficiencies are common in lower income countries, especially among young children and women of reproductive age. These deficiencies are cause for serious concern because of their high prevalence and their associated complications, which include depressed immune function and increased risk and severity of infections, impaired neurocognitive development, and anemia, which together result in elevated mortality and reduced human productive capacity. A broad range of different intervention strategies are available to control MN deficiencies. At present, these interventions are usually implemented at a national scale through different public and private sector entities, often with little coordination. We have developed a set of models based on the estimated ability of different interventions to achieve effective coverage and the necessary financial resources required to deploy these interventions. The models provide a unified and transparent framework for considering different options using the common indicator of effective coverage. More specifically, information on nutritional benefits and costs are analyzed using an economic optimization model to identify the mix of interventions that could be delivered to specific target groups in particular geographic areas to achieve a desired level of effective coverage at lowest cost. Alternatively, these optimization models can be developed to identify the combination of interventions needed to achieve the maximum effective coverage, given specified budgetary limitations. The results of these models can be useful input into policy-making processes. To introduce this analytical approach, the set of papers in this volume addresses the problem of vitamin A deficiency among young children in Cameroon.

Zinc Deficiency in Latin America and the Caribbean

BACKGROUND

Zinc deficiency affects multiple vital functions in the life cycle, especially growth. Limited information is available on the magnitude of zinc deficiency in Latin America and the Caribbean.

OBJECTIVE

To examine the latest available information on both the prevalence of zinc deficiency and the risk of zinc deficiency in Latin America and the Caribbean.

METHODS

The prevalence of zinc deficiency was identified through a systematic review looking for the latest available data on serum zinc concentrations from surveys or studies with national representativeness conducted in Latin America and the Caribbean. The risk of zinc deficiency in Latin America and the Caribbean was estimated based on dietary zinc inadequacy (according to the 2011 National Food Balance Sheets) and stunting in children under 5 years of age.

RESULTS

Only four countries had available national biochemical data. Mexican, Colombian, Ecuadorian, and Guatemalan children under 6 years of age and women 12 to 49 years of age had a high prevalence of zinc deficiency (19.1% to 56.3%). The countries with the highest risk of zinc deficiency (estimated prevalence of inadequate zinc intake > 25% plus prevalence of stunting > 20%) were Belize, Bolivia, El Salvador, Guatemala, Haiti, Honduras, Nicaragua, and Saint Vincent and the Grenadines. Zinc dietary inadequacy was directly correlated with stunting (r = 0.64, p < .001).

CONCLUSIONS

Prevalence data from the four available Latin America and Caribbean national surveys indicate a high prevalence of zinc deficiency in children under 6 years of age and women 12 to 49 years of age. High rates of both estimated zinc dietary inadequacy and stunting were also reported in most Latin America and Caribbean countries.

Zinc involvement in opioid addiction and analgesia--should zinc supplementation be recommended for opioid-treated persons?

INTRODUCTION

Zinc chelators were shown to facilitate some opioid-withdrawal signs in animals. Zinc deficiency, which affects more than 15% the world's population, is also common among opioid consumers and opioid-treated animals exhibit misbalances of zinc distribution.

AIM

The present study focuses on how zinc ions interfere with opioid dependence/addiction and analgesia, trying to preliminary discuss if zinc supplementation in opioid-users should be recommended in order to reduce the risk of addiction.

METHODS

All relevant literature was searched up to April 2015. The search was performed using the term "zinc" plus combinations of following terms: "opioid receptors", "opioid" or representatives of this class, "addiction", "dependence", "analgesia", and "pain". Human, animal, in vitro studies and reviews were including.

RESULTS

Both human and animal studies revealed decreased serum zinc under opioid-administration conditions, attributed mainly to increased urinary elimination (humans) or redistribution (animals). Moreover, animal studies revealed decreased brain zinc levels in morphine-treated animals, with increased zinc hepatic levels, but also an enhancement of endogenous opioid system activity and a possible reduction of morphine withdrawal by zinc. In vitro studies revealed reduction of opioid ligands binding to receptors by zinc. However, the very few in vivo animal studies on opioid analgesia revealed controversial results, as zinc demonstrated clear analgesic effect, but zinc associated to opioids doesn't result in a potentiation of the analgesic effect.

CONCLUSION

Zinc dietary supplementation in patients treated with opioids for cancer-related chronic pain should be considered, due to the high incidence of zinc deficiency, also well-documented in opioid consumers. The low toxicity of orally-administered zinc also pleads for this idea. The main contra-argument to zinc administration in opioid-treated persons is related to the way zinc influences opioid-induced analgesia.

Nutrition and maternal, neonatal, and child health

This article reviews the central role of nutrition in advancing the maternal, newborn, and child health agenda with a focus on evidence for effective interventions generated using randomized controlled trials in low- and middle-income countries (LMIC). The 1000 days spanning from conception to 2 years of life are a critical period of time when nutritional needs must be ensured; failure to do so can lead to adverse impacts on short-term survival as well as long-term health and development [corrected]. The burden of maternal mortality continues to be high in many under-resourced settings; prenatal calcium supplementation in populations with low intakes can reduce the risk of pre-eclampsia and eclampsia morbidity and mortality and is recommended, and antenatal iron-folic acid use in many countries may reduce anemia, a condition that may be an underlying factor in postpartum hemorrhage. Sufficient evidence exists to promote multiple micronutrient supplementation during pregnancy to reduce fetal growth restriction and low birth weight. Early initiation of breastfeeding (within an hour), exclusive breastfeeding in the first 6 months of life, and vitamin A supplementation in the first few days of life in Asia (but not in Africa) reduce infant mortality. Biannual large-dose vitamin A supplements to children 6-59 months of age and zinc for treatment of diarrhea continue to be important strategies for improving child health and survival. Early nutrition and micronutrient status can influence child development but should be integrated with early responsive learning interventions. Future research is needed that goes beyond the 1000 days to ensure adequate preconceptional nutrition and health, with special emphasis on adolescents who contribute to a large proportion of first births in many LMIC. Thus, we make the case for integrating proven nutrition interventions with those for health in pregnant women, and with those for health and child development in neonates, infants, and young children to help advance the global MNCH agenda.

Oral zinc supplements are ineffective for treating acute dehydrating diarrhoea in 5-12-year-olds

AIM

Many countries have guidelines recommending the use of oral zinc in acute dehydrating diarrhoea in children aged 2 months to 5 years of age, but no guidelines exist for older children. This study tested how effective existing recommendations are in children from 5 to 12 years of age.

METHODS

Children hospitalised with acute dehydrating diarrhoea (n = 134) were randomised to receive 40 mg of oral zinc sulphate tablets or a placebo for 14 days. The primary outcome variable was the time taken for diarrhoea to stop. Secondary outcome variables included time taken for rehydration, duration of hospitalisation and recurrence of diarrhoea in the next 3 months.

RESULTS

The median time for resolution of diarrhoea was 60 h in both groups. The zinc group was marginally better, but not statistically significant, for resolution (hazard ratio = 0.89, 95% CI 0.63-1.24), rehydration (hazard ratio = 0.93, 95% CI 0.66-1.32) and hospitalisation (hazard ratio = 0.94, 95% CI 0.67-1.34). The risk ratio of recurrence for zinc versus placebo (95% CI) was 0.65 [0.37-1.23] [p = 0.11].

CONCLUSION

Daily zinc supplements (40 mg for 14 days) in children aged 5-12 years with acute dehydrating diarrhoea did not shorten the duration of diarrhoea or reduce subsequent episodes. Further adequately sized, community-based trials are needed.

Dietary calcium and zinc deficiency risks are decreasing but remain prevalent

Globally, more than 800 million people are undernourished while >2 billion people have one or more chronic micronutrient deficiencies (MNDs). More than 6% of global mortality and morbidity burdens are associated with undernourishment and MNDs. Here we show that, in 2011, 3.5 and 1.1 billion people were at risk of calcium (Ca) and zinc (Zn) deficiency respectively due to inadequate dietary supply. The global mean dietary supply of Ca and Zn in 2011 was 684 ± 211 and 16 ± 3 mg capita(-1) d(-1) (± SD) respectively. Between 1992 and 2011, global risk of deficiency of Ca and Zn decreased from 76 to 51%, and 22 to 16%, respectively. Approximately 90% of those at risk of Ca and Zn deficiency in 2011 were in Africa and Asia. To our knowledge, these are the first global estimates of dietary Ca deficiency risks based on food supply. We conclude that continuing to reduce Ca and Zn deficiency risks through dietary diversification and food and agricultural interventions including fortification, crop breeding and use of micronutrient fertilisers will remain a significant challenge.

Crosstalk between Zinc Status and Giardia Infection: A New Approach

Zinc supplementation has been shown to reduce the incidence and prevalence of diarrhea; however, its anti-diarrheal effect remains only partially understood. There is now growing evidence that zinc can have pathogen-specific protective effects. Giardiasis is a common yet neglected cause of acute-chronic diarrheal illness worldwide which causes disturbances in zinc metabolism of infected children, representing a risk factor for zinc deficiency. How zinc metabolism is compromised by Giardia is not well understood; zinc status could be altered by intestinal malabsorption, organ redistribution or host-pathogen competition. The potential metal-binding properties of Giardia suggest unusual ways that the parasite may interact with its host. Zinc supplementation was recently found to reduce the rate of diarrhea caused by Giardia in children and to upregulate humoral immune response in Giardia-infected mice; in vitro and in vivo, zinc-salts enhanced the activity of bacitracin in a zinc-dose-dependent way, and this was not due to zinc toxicity. These findings reflect biological effect of zinc that may impact significantly public health in endemic areas of infection. In this paper, we shall explore one direction of this complex interaction, discussing recent information regarding zinc status and its possible contribution to the outcome of the encounter between the host and Giardia.

Inflammation and Nutritional Science for Programs/Policies and Interpretation of Research Evidence (INSPIRE)

An increasing recognition has emerged of the complexities of the global health agenda—specifically, the collision of infections and noncommunicable diseases and the dual burden of over- and undernutrition. Of particular practical concern are both 1) the need for a better understanding of the bidirectional relations between nutritional status and the development and function of the immune and inflammatory response and 2) the specific impact of the inflammatory response on the selection, use, and interpretation of nutrient biomarkers. The goal of the Inflammation and Nutritional Science for Programs/Policies and Interpretation of Research Evidence (INSPIRE) is to provide guidance for those users represented by the global food and nutrition enterprise. These include researchers (bench and clinical), clinicians providing care/treatment, those developing and evaluating programs/interventions at scale, and those responsible for generating evidence-based policy. The INSPIRE process included convening 5 thematic working groups (WGs) charged with developing summary reports around the following issues: 1) basic overview of the interactions between nutrition, immune function, and the inflammatory response; 2) examination of the evidence regarding the impact of nutrition on immune function and inflammation; 3) evaluation of the impact of inflammation and clinical conditions (acute and chronic) on nutrition; 4) examination of existing and potential new approaches to account for the impact of inflammation on biomarker interpretation and use; and 5) the presentation of new approaches to the study of these relations. Each WG was tasked with synthesizing a summary of the evidence for each of these topics and delineating the remaining gaps in our knowledge. This review consists of a summary of the INSPIRE workshop and the WG deliberations.

Differential Natural Selection of Human Zinc Transporter Genes between African and Non-African Populations

Zinc transporters play important roles in all eukaryotes by maintaining the rational zinc concentration in cells. However, the diversity of zinc transporter genes (ZTGs) remains poorly studied. Here, we investigated the genetic diversity of 24 human ZTGs based on the 1000 Genomes data. Some ZTGs show small population differences, such as SLC30A6 with a weighted-average FST (WA-FST = 0.015), while other ZTGs exhibit considerably large population differences, such as SLC30A9 (WA-FST = 0.284). Overall, ZTGs harbor many more highly population-differentiated variants compared with random genes. Intriguingly, we found that SLC30A9 was underlying natural selection in both East Asians (EAS) and Africans (AFR) but in different directions. Notably, a non-synonymous variant (rs1047626) in SLC30A9 is almost fixed with 96.4% A in EAS and 92% G in AFR, respectively. Consequently, there are two different functional haplotypes exhibiting dominant abundance in AFR and EAS, respectively. Furthermore, a strong correlation was observed between the haplotype frequencies of SLC30A9 and distributions of zinc contents in soils or crops. We speculate that the genetic differentiation of ZTGs could directly contribute to population heterogeneity in zinc transporting capabilities and local adaptations of human populations in regard to the local zinc state or diets, which have both evolutionary and medical implications.

Antidepressant activity of fluoxetine in the zinc deficiency model in rats involves the NMDA receptor complex

The zinc deficiency animal model of depression has been proposed; however, it has not been validated in a detailed manner. We have recently shown that depression-like behavior induced by dietary zinc restriction is associated with up-regulation of hippocampal N-methyl-d-aspartate receptor (NMDAR). Here we examined the effects of chronic administration of a selective serotonin reuptake inhibitor, fluoxetine (FLX), on behavioral and biochemical alterations (within NMDAR signaling pathway) induced by zinc deficiency. Male Sprague Dawley rats were fed a zinc adequate diet (ZnA, 50mg Zn/kg) or a zinc deficient diet (ZnD, 3mg Zn/kg) for 4 weeks. Then, FLX treatment (10mg/kg, i.p.) begun. Following 2 weeks of FLX administration the behavior of the rats was examined in the forced swim test (FST) and the spontaneous locomotor activity test. Twenty four hours later tissue was harvested. The proteins of NMDAR (GluN1, GluN2A and GluN2B) or AMPAR (GluA1) subunits, p-CREB and BDNF in the hippocampus (Western blot) and serum zinc level (TXRF) were examined. Depression-like behavior induced by ZnD in the FST was sensitive to chronic treatment with FLX. ZnD increased levels of GluN1, GluN2A, GluN2B and decreased pS485-GluA1, p-CREB and BDNF proteins. Administration of FLX counteracted the zinc restriction-induced changes in serum zinc level and hippocampal GluN1, GluN2A, GluN2B and p-CREB but not BDNF or pS845-GluA1 protein levels. This finding adds new evidence to the predictive validity of the proposed zinc deficiency model of depression. Antidepressant-like activity of FLX in the zinc deficiency model is associated with NMDAR complex.

Biomarkers of Nutrition for Development (BOND)-Zinc Review

Zinc is required for multiple metabolic processes as a structural, regulatory, or catalytic ion. Cellular, tissue, and whole-body zinc homeostasis is tightly controlled to sustain metabolic functions over a wide range of zinc intakes, making it difficult to assess zinc insufficiency or excess. The BOND (Biomarkers of Nutrition for Development) Zinc Expert Panel recommends 3 measurements for estimating zinc status: dietary zinc intake, plasma zinc concentration (PZC), and height-for-age of growing infants and children. The amount of dietary zinc potentially available for absorption, which requires an estimate of dietary zinc and phytate, can be used to identify individuals and populations at risk of zinc deficiency. PZCs respond to severe dietary zinc restriction and to zinc supplementation; they also change with shifts in whole-body zinc balance and clinical signs of zinc deficiency. PZC cutoffs are available to identify individuals and populations at risk of zinc deficiency. However, there are limitations in using the PZC to assess zinc status. PZCs respond less to additional zinc provided in food than to a supplement administered between meals, there is considerable interindividual variability in PZCs with changes in dietary zinc, and PZCs are influenced by recent meal consumption, the time of day, inflammation, and certain drugs and hormones. Insufficient data are available on hair, urinary, nail, and blood cell zinc responses to changes in dietary zinc to recommend these biomarkers for assessing zinc status. Of the potential functional indicators of zinc, growth is the only one that is recommended. Because pharmacologic zinc doses are unlikely to enhance growth, a growth response to supplemental zinc is interpreted as indicating pre-existing zinc deficiency. Other functional indicators reviewed but not recommended for assessing zinc nutrition in clinical or field settings because of insufficient information are the activity or amounts of zinc-dependent enzymes and proteins and biomarkers of oxidative stress, inflammation, or DNA damage.

Zinc absorption from biofortified maize meets the requirements of young rural Zambian children

BACKGROUND

The zinc content of maize, a major global food staple, is generally insufficient alone to meet the requirements of young children.

OBJECTIVES

The primary objective of this study was to determine whether substitution of biofortified maize (34 μg zinc/g grain) for control maize (21 μg zinc/g) was adequate to meet zinc physiologic requirements in young children for whom maize was the major food staple. A secondary objective was to compare total daily zinc absorption when maize flour was fortified with zinc oxide to a total concentration of 60 μg zinc/g.

METHODS

Participants included 60 rural Zambian children with a mean age of 29 mo who were randomly assigned to receive 1 of 3 maize types (control, biofortified, or fortified) all of which were readily consumed (>100 g on 1 d). Total daily zinc intake (from maize and low-zinc relish) was determined from duplicate diet collections. Multiplication by fractional absorption of zinc, measured by a dual isotope ratio technique, determined the total daily zinc absorption on the day the test meals were given.

RESULTS

The mean ± SD total daily zinc intake (milligrams per day) from the biofortified maize (5.0 ± 2.2) was higher (P < 0.0001) than for the control maize (2.3 ± 0.9). Intake of zinc from the fortified maize (6.3 ± 2.6) did not differ from the biofortified maize. Fractional absorption of zinc from control maize (0.28 ± 0.10) did not differ from the biofortified maize (0.22 ± 0.06). Total daily absorption of zinc (milligrams per day) from the biofortified maize (1.1 ± 0.5) was higher (P = 0.0001) than for the control maize (0.6 ± 0.2), but did not differ from the fortified maize (1.2 ± 0.4).

CONCLUSIONS

These results indicate that feeding biofortified maize can meet zinc requirements and provide an effective dietary alternative to regular maize for this vulnerable population. This trial was registered at clinicaltrials.gov as NCT02208635.

Heterodimerization, altered subcellular localization, and function of multiple zinc transporters in viable cells using bimolecular fluorescence complementation

Zinc plays a crucial role in numerous key physiological functions. Zinc transporters (ZnTs) mediate zinc efflux and compartmentalization in intracellular organelles; thus, ZnTs play a central role in zinc homeostasis. We have recently shown the in situ dimerization and function of multiple normal and mutant ZnTs using bimolecular fluorescence complementation (BiFC). Prompted by these findings, we here uncovered the heterodimerization, altered subcellular localization, and function of multiple ZnTs in live cells using this sensitive BiFC technique. We show that ZnT1, -2, -3, and -4 form stable heterodimers at distinct intracellular compartments, some of which are completely different from their homodimer localization. Specifically, unlike the plasma membrane (PM) localization of ZnT1 homodimers, ZnT1-ZnT3 heterodimers localized at intracellular vesicles. Furthermore, upon heterodimerization with ZnT1, the zinc transporters ZnT2 and ZnT4 surprisingly localized at the PM, as opposed to their vesicular homodimer localization. We further demonstrate the deleterious effect that the G87R-ZnT2 mutation, associated with transient neonatal zinc deficiency, has on ZnT1, ZnT3, and ZnT4 upon heterodimerization. The functionality of the various ZnTs was assessed by the dual BiFC-Zinquin assay. We also undertook a novel transfection competition assay with ZnT cDNAs to confirm that the driving force for heterodimer formation is the core structure of ZnTs and not the BiFC tags. These findings uncover a novel network of homo- and heterodimers of ZnTs with distinct subcellular localizations and function, hence highlighting their possible role in zinc homeostasis under physiological and pathological conditions.

Behavioral impairments in animal models for zinc deficiency

Apart from teratogenic and pathological effects of zinc deficiency such as the occurrence of skin lesions, anorexia, growth retardation, depressed wound healing, altered immune function, impaired night vision, and alterations in taste and smell acuity, characteristic behavioral changes in animal models and human patients suffering from zinc deficiency have been observed. Given that it is estimated that about 17% of the worldwide population are at risk for zinc deficiency and that zinc deficiency is associated with a variety of brain disorders and disease states in humans, it is of major interest to investigate, how these behavioral changes will affect the individual and a putative course of a disease. Thus, here, we provide a state of the art overview about the behavioral phenotypes observed in various models of zinc deficiency, among them environmentally produced zinc deficient animals as well as animal models based on a genetic alteration of a particular zinc homeostasis gene. Finally, we compare the behavioral phenotypes to the human condition of mild to severe zinc deficiency and provide a model, how zinc deficiency that is associated with many neurodegenerative and neuropsychological disorders might modify the disease pathologies.

Enriching rice with Zn and Fe while minimizing Cd risk

Enriching iron (Fe) and zinc (Zn) content in rice grains, while minimizing cadmium (Cd) levels, is important for human health and nutrition. Natural genetic variation in rice grain Zn enables Zn-biofortification through conventional breeding, but limited natural Fe variation has led to a need for genetic modification approaches, including over-expressing genes responsible for Fe storage, chelators, and transporters. Generally, Cd uptake and allocation is associated with divalent metal cations (including Fe and Zn) transporters, but the details of this process are still unknown in rice. In addition to genetic variation, metal uptake is sometimes limited by its bioavailability in the soil. The availability of Fe, Zn, and Cd for plant uptake varies widely depending on soil redox potential. The typical practice of flooding rice increases Fe while decreasing Zn and Cd availability. On the other hand, moderate soil drying improves Zn uptake but also increases Cd and decreases Fe uptake. Use of Zn- or Fe-containing fertilizers complements breeding efforts by providing sufficient metals for plant uptake. In addition, the timing of nitrogen fertilization has also been shown to affect metal accumulation in grains. The purpose of this mini-review is to identify knowledge gaps and prioritize strategies for improving the nutritional value and safety of rice.

Zinc deficiency in infants and children: a review of its complex and synergistic interactions

Zinc deficiency is estimated to contribute to over half a million deaths per year in infants and children under 5 years of age. This paper reviews the features of mild-to-moderate zinc deficiency, which include growth faltering, deficits in immune function and altered integrity and function of the gastro-intestinal tract. Sub-clinical features include oxidative stress and a pro-inflammatory state. The homeostatic response to low dietary zinc intake by increasing absorption is limited, especially if the source of zinc is of poor bioavailability, and conservation of endogenous intestinal losses is a critical component of adaptation. Owing to low zinc intakes, older breastfed infants, especially those of low birthweight, are predictably at risk of zinc deficiency if complementary food choices are unfortified and/or low in zinc. Host factors such as young age, poor intra-uterine zinc accretion owing to poor maternal status and/or prematurity, and gastro-intestinal dysfunction also potently predispose to zinc deficiency. Environmental enteropathy, which is prevalent in low-resource settings, may substantially impair zinc absorption and/or increase endogenous losses, and thus lead to relatively high zinc requirements. Emerging evidence highlights common features between chronic inflammation and zinc deficiency, and each may exacerbate the other. More investigations of zinc homeostasis in populations in low-resource settings are needed to better quantify absorption capacity and losses. Effective preventive strategies must address potentially higher zinc requirements as well as the underlying context that perpetuates a vicious cycle of zinc deficiency and multiple adverse outcomes.

Zinc supplementation reduced DNA breaks in Ethiopian women

Assessment of zinc status remains a challenge largely because serum/plasma zinc may not accurately reflect an individual's zinc status. The comet assay, a sensitive method capable of detecting intracellular DNA strand breaks, may serve as a functional biomarker of zinc status. We hypothesized that effects of zinc supplementation on intracellular DNA damage could be assessed from samples collected in field studies in Ethiopia using the comet assay. Forty women, from villages where reported consumption of meat was less than once per month and phytate levels were high, received 20 mg zinc as zinc sulfate or placebo daily for 17 days in a randomized placebo-controlled trial. Plasma zinc concentrations were determined by inductively coupled plasma mass spectrometry. Cells from whole blood at the baseline and end point of the study were embedded in agarose, electrophoresed, and stained before being scored by an investigator blinded to the treatments. Although zinc supplementation did not significantly affect plasma zinc, mean (± SEM) comet tail moment measurement of supplemented women decreased from 39.7 ± 2.7 to 30.0 ± 1.8 (P< .005), indicating a decrease in DNA strand breaks in zinc-supplemented individuals. These findings demonstrated that the comet assay could be used as a functional assay to assess the effects of zinc supplementation on DNA integrity in samples collected in a field setting where food sources of bioavailable zinc are limited. Furthermore, the comet assay was sufficiently sensitive to detect changes in zinc status as a result of supplementation despite no significant changes in plasma zinc.

Significance of Zn(2+) signaling in cognition: insight from synaptic Zn(2+) dyshomeostasis

Zinc is concentrated in the synaptic vesicles via zinc transporter-3 (ZnT3), released from glutamatergic (zincergic) neuron terminals, and serves as a signal factor (Zn(2+) signal) in the intracellular (cytosol) compartment as well as in the extracellular compartment. Synaptic Zn(2+) signaling is dynamically linked to neurotransmission via glutamate and is involved in synaptic plasticity such as long-term potentiation (LTP) and cognitive activity. Zinc concentration in the synaptic vesicles is correlated with ZnT3 protein expression and potentially decreased under chronic zinc deficiency. Synaptic vesicle serves as a large pool for Zn(2+) signaling and other organelles might also serve as a pool for Zn(2+) signaling. ZnT3KO mice and zinc-deficient animals, which lack or reduce Zn(2+) release into the extracellular space by action potentials, are able to recognize novel or displaced objects normally. However, the amount of Zn(2+) functioning as a signal factor increases along with brain development. Exogenous Zn(2+) lowers the threshold in hippocampal CA1 LTP induction in young rat. Furthermore, ZnT3KO mice lose advanced cognition such as contextual discrimination. It is likely that the optimal range of synaptic Zn(2+) signaling is involved in cognitive activity. On the basis of the findings on the relationship between dyshomeostasis of synaptic Zn(2+) and cognition, this paper summarizes the possible involvement of intracellular Zn(2+) signaling in cognitive ability.

Low serum zinc is associated with elevated risk of cadmium nephrotoxicity

BACKGROUND

Despite animal evidence suggests that zinc modulates cadmium nephrotoxicity, limited human data are available.

OBJECTIVE

To test the hypothesis that low serum zinc concentrations may increase the risk of cadmium-mediated renal dysfunction in humans.

METHODS

Data from 1545 subjects aged 20 or older in the National Health and Nutrition Examination Survey (NHANES), 2011-2012 were analyzed. Renal function was defined as impaired when estimated glomerular filtration rate (eGFR) fell below 60 ml/min/1.73 m(2) and/or the urinary albumin-to-creatinine ratio surpassed 2.5 in men and 3.5mg/mmol in women.

RESULTS

Within the study cohort, 117 subjects had reduced eGFR and 214 had elevated urinary albumin. After adjusting for potential confounders, subjects with elevated blood cadmium (>0.53 μg/L) were more likely to have a reduced eGFR (odds ratio [OR]=2.21, 95% confidence interval [CI]: 1.09-4.50) and a higher urinary albumin (OR=2.04, 95% CI: 1.13-3.69) than their low cadmium (<0.18 μg/L) peers. In addition, for any given cadmium exposure, low serum zinc is associated with elevated risk of reduced eGFR (OR=3.38, 95% CI: 1.39-8.28). A similar increase in the odds ratio was observed between declining serum zinc and albuminuria but failed to reach statistical significance. Those with lower serum zinc/blood cadmium ratios were likewise at a greater risk of renal dysfunction (p<0.01).

CONCLUSIONS

This study results suggest that low serum zinc concentrations are associated with an increased risk of cadmium nephrotoxicity. Elevated cadmium exposure is global public health issue and the assessment of zinc nutritional status may be an important covariate in determining its effective renal toxicity.

Multiple micronutrient supplementation during pregnancy and lactation in low-to-middle-income developing country settings: impact on pregnancy outcomes

BACKGROUND

Malnutrition, including micronutrient deficiencies, remains one of the major public health challenges, particularly in low-to-middle-income countries. Micronutrient deficiencies affect people of all ages, but its effects appear more devastating in pregnant women and children. Poor maternal nutrition contributes to at least 20% of maternal deaths and increases the probability of poor pregnancy outcomes including intrauterine growth restriction, resulting in low birth weight, stunting, wasting and mortality. Key Messages: Several strategies have been employed to provide pregnant women with micronutrients. These strategies include education, dietary modification, food provision, agricultural interventions, supplementation and fortification either alone or in combination. Micronutrient supplementation is the most widely practiced intervention to prevent and manage single or multiple micronutrient deficiencies. Micronutrient supplementation either alone or in combination has shown to be effective in improving maternal, birth and child outcomes.

CONCLUSIONS

There is a need to focus on maternal micronutrient status as a continuum from the periconceptional period throughout pregnancy to lactation. Given the wide prevalence of multiple micronutrient deficiencies in low-to-middle-income countries, the challenge is to implement intervention strategies that combine appropriate maternal and child health interventions with micronutrient interventions.

The associations between serum zinc levels and metabolic syndrome in the Korean population: findings from the 2010 Korean National Health and Nutrition Examination Survey

The prevalence of metabolic syndrome has been increasing rapidly worldwide. The functions of zinc may have a potential association with metabolic syndrome, but such associations have not been investigated extensively. Therefore, we examined the relationship between serum zinc levels and metabolic syndrome or metabolic risk factors among South Korean adults ≥20 years of age. The analysis used data from the Korean National Health and Nutrition Examination Survey, a cross-sectional survey of Korean civilians, conducted from January to December 2010. A total of 1,926 participants were analyzed in this study. Serum zinc levels in men were negatively associated with elevated fasting glucose (adjusted odds ratio [aOR], 0.58; 95% confidence interval [CI], 0.36–0.93) and positively associated with elevated triglycerides (aOR, 1.47; 95% CI, 1.01–2.13). A difference in serum zinc levels was detected in women, depending on the number of metabolic syndrome components (p = 0.002). Furthermore, serum zinc levels showed a decreasing trend with increasing numbers of metabolic syndrome components in women with metabolic syndrome. These findings suggest that serum zinc levels might be associated with metabolic syndrome or metabolic risk factors. Further gender-specific studies are needed to evaluate the effect of dietary or supplemental zinc intake on metabolic syndrome.

Dietary mineral supplies in Africa

Dietary micronutrient deficiencies (MNDs) are widespread, yet their prevalence can be difficult to assess. Here, we estimate MND risks due to inadequate intakes for seven minerals in Africa using food supply and composition data, and consider the potential of food-based and agricultural interventions. Food Balance Sheets (FBSs) for 46 countries were integrated with food composition data to estimate per capita supply of calcium (Ca), copper (Cu), iron (Fe), iodine (I), magnesium (Mg), selenium (Se) and zinc (Zn), and also phytate. Deficiency risks were quantified using an estimated average requirement (EAR) 'cut-point' approach. Deficiency risks are highest for Ca (54% of the population), followed by Zn (40%), Se (28%) and I (19%, after accounting for iodized salt consumption). The risk of Cu (1%) and Mg (<1%) deficiency are low. Deficiency risks are generally lower in the north and west of Africa. Multiple MND risks are high in many countries. The population-weighted mean phytate supply is 2770 mg capita(-1) day(-1). Deficiency risks for Fe are lower than expected (5%). However, 'cut-point' approaches for Fe are sensitive to assumptions regarding requirements; e.g. estimates of Fe deficiency risks are 43% under very low bioavailability scenarios consistent with high-phytate, low-animal protein diets. Fertilization and breeding strategies could greatly reduce certain MNDs. For example, meeting HarvestPlus breeding targets for Zn would reduce dietary Zn deficiency risk by 90% based on supply data. Dietary diversification or direct fortification is likely to be needed to address Ca deficiency risks.

An overview of the nutritional value of beef and lamb meat from South America

The southern region of South America, a subtropical and temperate zone, is an important region for the production of beef and lamb meat, which is mainly produced in extensive pasture-based systems. Because of its content in highly valuable nutrients such as iron, zinc, selenium, fatty acids, and vitamins, meat is a unique and necessary food for the human diet in order to secure a long and healthy life, without nutritional deficiencies. Beef and lamb production systems based on temperate or tropical grasslands show interesting and, in some cases, a differential content in minerals, fatty acids and vitamins. This review deals with the distinctive aspects of the nutritional quality of beef and lamb meat produced in this region in terms of nutritional composition and the bioavailability of key nutrients related to its contribution for a healthy diet for all ages.

Preventive zinc supplementation for children, and the effect of additional iron: a systematic review and meta-analysis

OBJECTIVE

Zinc deficiency is widespread, and preventive supplementation may have benefits in young children. Effects for children over 5 years of age, and effects when coadministered with other micronutrients are uncertain. These are obstacles to scale-up. This review seeks to determine if preventive supplementation reduces mortality and morbidity for children aged 6 months to 12 years.

DESIGN

Systematic review conducted with the Cochrane Developmental, Psychosocial and Learning Problems Group. Two reviewers independently assessed studies. Meta-analyses were performed for mortality, illness and side effects.

DATA SOURCES

We searched multiple databases, including CENTRAL and MEDLINE in January 2013. Authors were contacted for missing information.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Randomised trials of preventive zinc supplementation. Hospitalised children and children with chronic diseases were excluded.

RESULTS

80 randomised trials with 205 401 participants were included. There was a small but non-significant effect on all-cause mortality (risk ratio (RR) 0.95 (95% CI 0.86 to 1.05)). Supplementation may reduce incidence of all-cause diarrhoea (RR 0.87 (0.85 to 0.89)), but there was evidence of reporting bias. There was no evidence of an effect of incidence or prevalence of respiratory infections or malaria. There was moderate quality evidence of a very small effect on linear growth (standardised mean difference 0.09 (0.06 to 0.13)) and an increase in vomiting (RR 1.29 (1.14 to 1.46)). There was no evidence of an effect on iron status. Comparing zinc with and without iron cosupplementation and direct comparisons of zinc plus iron versus zinc administered alone favoured cointervention for some outcomes and zinc alone for other outcomes. Effects may be larger for children over 1 year of age, but most differences were not significant.

CONCLUSIONS

Benefits of preventive zinc supplementation may outweigh any potentially adverse effects in areas where risk of zinc deficiency is high. Further research should determine optimal intervention characteristics and delivery strategies.

Zinc supplementation for preventing mortality, morbidity, and growth failure in children aged 6 months to 12 years of age

BACKGROUND

Zinc deficiency is prevalent in low- and middle-income countries, and contributes to significant diarrhoea-, pneumonia-, and malaria-related morbidity and mortality among young children. Zinc deficiency also impairs growth.

OBJECTIVES

To assess the effects of zinc supplementation for preventing mortality and morbidity, and for promoting growth, in children aged six months to 12 years of age.

SEARCH METHODS

Between December 2012 and January 2013, we searched CENTRAL, MEDLINE, MEDLINE In-Process and Other Non-Indexed Citations, Embase, African Index Medicus, Conference Proceedings Citation Index, Dissertation Abstracts, Global Health, IndMED, LILACS, WHOLIS, metaRegister of Controlled Trials, and WHO ICTRP.

SELECTION CRITERIA

Randomised controlled trials of preventive zinc supplementation in children aged six months to 12 years compared with no intervention, a placebo, or a waiting list control. We excluded hospitalised children and children with chronic diseases or conditions. We excluded food fortification or intake, sprinkles, and therapeutic interventions.

DATA COLLECTION AND ANALYSIS

Two authors screened studies, extracted data, and assessed risk of bias. We contacted trial authors for missing information.

MAIN RESULTS

We included 80 randomised controlled trials with 205,401 eligible participants. We did not consider that the evidence for the key analyses of morbidity and mortality outcomes were affected by risk of bias. The risk ratio (RR) for all-cause mortality was compatible with a reduction and a small increased risk of death with zinc supplementation (RR 0.95, 95% confidence interval (CI) 0.86 to 1.05, 14 studies, high-quality evidence), and also for cause-specific mortality due to diarrhoea (RR 0.95, 95% CI 0.69 to 1.31, four studies, moderate-quality evidence), lower respiratory tract infection (LRTI) (RR 0.86, 95% CI 0.64 to 1.15, three studies, moderate-quality evidence), or malaria (RR 0.90, 95% CI 0.77 to 1.06, two studies, moderate-quality evidence).Supplementation reduced diarrhoea morbidity, including the incidence of all-cause diarrhoea (RR 0.87, 95% CI 0.85 to 0.89, 26 studies, moderate-quality evidence), but the results for LRTI and malaria were imprecise: LRTI (RR 1, 95% CI 0.94 to 1.07, 12 studies, moderate-quality evidence); malaria (RR 1.05, 95% 0.95 to 1.15, four studies, moderate-quality evidence).There was moderate-quality evidence of a very small improvement in height with supplementation (standardised mean difference (SMD) -0.09, 95% CI -0.13 to -0.06; 50 studies), but the size of this effect might not be clinically important. There was a medium to large positive effect on zinc status.Supplementation was associated with an increase in the number of participants with at least one vomiting episode (RR 1.29, 95% CI 1.14 to 1.46, five studies, high-quality evidence). We found no clear evidence of benefit or harm of supplementation with regard to haemoglobin or iron status. Supplementation had a negative effect on copper status.

AUTHORS' CONCLUSIONS

In our opinion, the benefits of preventive zinc supplementation outweigh the harms in areas where the risk of zinc deficiency is relatively high. Further research should determine optimal intervention characteristics such as supplement dose.

The Lives Saved Tool (LiST) as a model for diarrhea mortality reduction

BACKGROUND

Diarrhea is a leading cause of morbidity and mortality among children under five years of age. The Lives Saved Tool (LiST) is a model used to calculate deaths averted or lives saved by past interventions and for the purposes of program planning when costly and time consuming impact studies are not possible.

DISCUSSION

LiST models the relationship between coverage of interventions and outputs, such as stunting, diarrhea incidence and diarrhea mortality. Each intervention directly prevents a proportion of diarrhea deaths such that the effect size of the intervention is multiplied by coverage to calculate lives saved. That is, the maximum effect size could be achieved at 100% coverage, but at 50% coverage only 50% of possible deaths are prevented. Diarrhea mortality is one of the most complex causes of death to be modeled. The complexity is driven by the combination of direct prevention and treatment interventions as well as interventions that operate indirectly via the reduction in risk factors, such as stunting and wasting. Published evidence is used to quantify the effect sizes for each direct and indirect relationship. Several studies have compared measured changes in mortality to LiST estimates of mortality change looking at different sets of interventions in different countries. While comparison work has generally found good agreement between the LiST estimates and measured mortality reduction, where data availability is weak, the model is less likely to produce accurate results. LiST can be used as a component of program evaluation, but should be coupled with more complete information on inputs, processes and outputs, not just outcomes and impact.

SUMMARY

LiST is an effective tool for modeling diarrhea mortality and can be a useful alternative to large and expensive mortality impact studies. Predicting the impact of interventions or comparing the impact of more than one intervention without having to wait for the results of large and expensive mortality studies is critical to keep programs focused and results oriented for continued reductions in diarrhea and all-cause mortality among children under five years of age.

The stunting syndrome in developing countries

Linear growth failure is the most common form of undernutrition globally. With an estimated 165 million children below 5 years of age affected, stunting has been identified as a major public health priority, and there are ambitious targets to reduce the prevalence of stunting by 40% between 2010 and 2025. We view this condition as a 'stunting syndrome' in which multiple pathological changes marked by linear growth retardation in early life are associated with increased morbidity and mortality, reduced physical, neurodevelopmental and economic capacity and an elevated risk of metabolic disease into adulthood. Stunting is a cyclical process because women who were themselves stunted in childhood tend to have stunted offspring, creating an intergenerational cycle of poverty and reduced human capital that is difficult to break. In this review, the mechanisms underlying linear growth failure at different ages are described, the short-, medium- and long-term consequences of stunting are discussed, and the evidence for windows of opportunity during the life cycle to target interventions at the stunting syndrome are evaluated.

Bioavailability of iron, zinc, and provitamin A carotenoids in biofortified staple crops

International research efforts, including those funded by HarvestPlus, a Challenge Program of the Consultative Group on International Agricultural Research (CGIAR), are focusing on conventional plant breeding to biofortify staple crops such as maize, rice, cassava, beans, wheat, sweet potatoes, and pearl millet to increase the concentrations of micronutrients that are commonly deficient in specific population groups of developing countries. The bioavailability of micronutrients in unfortified staple crops in developing regions is typically low, which raises questions about the efficacy of these crops to improve population micronutrient status. This review of recent studies of biofortified crops aims to assess the micronutrient bioavailability of biofortified staple crops in order to derive lessons that may help direct plant breeding and to infer the potential efficacy of food-based nutrition interventions. Although reducing the amounts of antinutrients and the conduction of food processing generally increases the bioavailability of micronutrients, antinutrients still possess important benefits, and food processing results in micronutrient loss. In general, biofortified foods with relatively higher micronutrient density have higher total absorption rates than nonbiofortified varieties. Thus, evidence supports the focus on efforts to breed plants with increased micronutrient concentrations in order to decrease the influence of inhibitors and to offset losses from processing.

Stunting prevalence, plasma zinc concentrations, and dietary zinc intakes in a nationally representative sample suggest a high risk of zinc deficiency among women and young children in Cameroon

Before initiating a mass zinc fortification program, this study assessed the prevalence of and risk factors for low zinc status among Cameroonian women and children. In a nationally representative survey, we randomly selected 30 clusters in each of 3 strata (North, South, and Yaoundé/Douala) and 10 households per cluster, each with a woman aged 15-49 y and a child aged 12-59 mo (n = 1002 households). Twenty-four-hour dietary recalls (with duplicates in a subset) and anthropometric measurements were conducted, and non-fasting blood was collected to measure plasma zinc concentration (PZC) and markers of inflammation. PZC was adjusted for methodologic factors (time of collection and processing, and presence of inflammation). The prevalence of stunting was 33% (32% South; 46% North; 13% Yaoundé/Douala). Among women, 82% had low adjusted PZC (<50 μg/dL for pregnant women; <66 μg/dL for others; 79% South, 89% North, 76% Yaoundé/Douala). Among children, 83% had low adjusted PZC (<65 μg/dL; 80% South, 92% North, 74% Yaoundé/Douala). Risk factors for low PZC among women and children and for low height-for-age Z-score among children were similar and included residence in the North region and rural areas and households with low socioeconomic status. Using estimated average requirement values from the International Zinc Nutrition Consultative Group (IZiNCG), 29 and 41% of women had inadequate zinc intakes, assuming moderate and low bioavailability, respectively, but only 8% of children had inadequate zinc intake. Depending on the estimated physiologic zinc requirement applied, 17% (IZiNCG) and 92% (Institute of Medicine) of women had inadequate absorbable zinc intakes. Total zinc intakes were greatest in the North region, possibly because of different dietary patterns in this area. Zinc deficiency is a public health problem among women and children in Cameroon, although PZC and dietary zinc yield different estimates of the prevalence of deficiency. Large-scale programs to improve zinc nutrition, including food fortification, are needed.

Biofortification of wheat grain with iron and zinc: integrating novel genomic resources and knowledge from model crops

Wheat, like many other staple cereals, contains low levels of the essential micronutrients iron and zinc. Up to two billion people worldwide suffer from iron and zinc deficiencies, particularly in regions with predominantly cereal-based diets. Although wheat flour is commonly fortified during processing, an attractive and more sustainable solution is biofortification, which requires developing new varieties of wheat with inherently higher iron and zinc content in their grains. Until now most studies aimed at increasing iron and zinc content in wheat grains have focused on discovering natural variation in progenitor or related species. However, recent developments in genomics and transformation have led to a step change in targeted research on wheat at a molecular level. We discuss promising approaches to improve iron and zinc content in wheat using knowledge gained in model grasses. We explore how the latest resources developed in wheat, including sequenced genomes and mutant populations, can be exploited for biofortification. We also highlight the key research and practical challenges that remain in improving iron and zinc content in wheat.

Is serum zinc associated with pancreatic beta cell function and insulin sensitivity in pre-diabetic and normal individuals? Findings from the Hunter Community Study

Aim

To determine if there is a difference in serum zinc concentration between normoglycaemic, pre-diabetic and type-2 diabetic groups and if this is associated with pancreatic beta cell function and insulin sensitivity in the former 2 groups.

Method

Cross sectional study of a random sample of older community-dwelling men and women in Newcastle, New South Wales, Australia. Beta cell function, insulin sensitivity and insulin resistance were calculated for normoglycaemic and prediabetes participants using the Homeostasis Model Assessment (HOMA-2) calculator.

Result

A total of 452 participants were recruited for this study. Approximately 33% (N = 149) had diabetes, 33% (N = 151) had prediabetes and 34% (N = 152) were normoglycaemic. Homeostasis Model Assessment (HOMA) parameters were found to be significantly different between normoglycaemic and prediabetes groups (p<0.001). In adjusted linear regression, higher serum zinc concentration was associated with increased insulin sensitivity (p = 0.01) in the prediabetic group. There was also a significant association between smoking and worse insulin sensitivity.

Conclusion

Higher serum zinc concentration is associated with increased insulin sensitivity. Longitudinal studies are required to determine if low serum zinc concentration plays a role in progression from pre-diabetes to diabetes.

Interactions between zinc deficiency and environmental enteropathy in developing countries

Zinc deficiency affects one-fifth of the world's population and leads to substantial morbidity and mortality. Environmental enteropathy (EE), a subclinical pathology of altered intestinal morphology and function, is almost universal among people living in developing countries and affects long-term growth and health. This review explores the overlapping nature of these 2 conditions and presents evidence for their interaction. EE leads to impaired zinc homeostasis, predominantly due to reduced absorptive capacity arising from disturbed intestinal architecture, and zinc deficiency exacerbates several of the proposed pathways that underlie EE, including intestinal permeability, enteric infection, and chronic inflammation. Ongoing zinc deficiency likely perpetuates the adverse outcomes of EE by worsening malabsorption, reducing intestinal mucosal immune responses, and exacerbating systemic inflammation. Although the etiology of EE is predominantly environmental, zinc deficiency may also have a role in its pathogenesis. Given the impact of both EE and zinc deficiency on morbidity and mortality in developing countries, better understanding the relation between these 2 conditions may be critical for developing combined interventions to improve child health.

Zinc signals and immune function

For more than 50 years, it has been known that zinc deficiency compromises immune function. During this time, knowledge about the biochemistry of zinc has continued to grow, but only recent years have provided in-depth molecular insights into the multiple aspects of zinc as a regulator of immunity. A network based on ZnT and ZIP proteins for transport and metallothionein for storage tightly regulates zinc availability, and virtually all aspects of innate and adaptive immunity are affected by zinc. In vivo, zinc deficiency alters the number and function of neutrophil granulocytes, monocytes, natural killer (NK)-, T-, and B-cells. T cell functions and balance between the different subsets are particularly susceptible to changes in zinc status. This article focuses in particular on the main mechanisms by which zinc ions exert essential functions in the immune system. On the one hand, this includes tightly protein bound zinc ions serving catalytic or structural functions in a multitude of different proteins, in particular enzymes and transcription factors. On the other hand, increasing evidence arises for a regulatory role of free zinc ions in signal transduction, especially in cells of the immune system. Identification of several molecular targets, including phosphatases, phosphodiesterases, caspases, and kinases suggest that zinc ions are a second messenger regulating signal transduction in various kinds of immune cells.

Maternal and child undernutrition and overweight in low-income and middle-income countries

Maternal and child malnutrition in low-income and middle-income countries encompasses both undernutrition and a growing problem with overweight and obesity. Low body-mass index, indicative of maternal undernutrition, has declined somewhat in the past two decades but continues to be prevalent in Asia and Africa. Prevalence of maternal overweight has had a steady increase since 1980 and exceeds that of underweight in all regions. Prevalence of stunting of linear growth of children younger than 5 years has decreased during the past two decades, but is higher in south Asia and sub-Saharan Africa than elsewhere and globally affected at least 165 million children in 2011; wasting affected at least 52 million children. Deficiencies of vitamin A and zinc result in deaths; deficiencies of iodine and iron, together with stunting, can contribute to children not reaching their developmental potential. Maternal undernutrition contributes to fetal growth restriction, which increases the risk of neonatal deaths and, for survivors, of stunting by 2 years of age. Suboptimum breastfeeding results in an increased risk for mortality in the first 2 years of life. We estimate that undernutrition in the aggregate--including fetal growth restriction, stunting, wasting, and deficiencies of vitamin A and zinc along with suboptimum breastfeeding--is a cause of 3·1 million child deaths annually or 45% of all child deaths in 2011. Maternal overweight and obesity result in increased maternal morbidity and infant mortality. Childhood overweight is becoming an increasingly important contributor to adult obesity, diabetes, and non-communicable diseases. The high present and future disease burden caused by malnutrition in women of reproductive age, pregnancy, and children in the first 2 years of life should lead to interventions focused on these groups.