What zinc supplementation does and does not achieve in diarrhea prevention: a systematic review and meta-analysis

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

BACKGROUND

Zinc deficiency is prevalent in low- and middle-income countries, and is considered a significant risk factor for morbidity, mortality, and linear growth failure. The effectiveness of preventive zinc supplementation in reducing prevalence of zinc deficiency needs to be assessed.

OBJECTIVES

To assess the effects of zinc supplementation for preventing mortality and morbidity, and for promoting growth, in children aged 6 months to 12 years.

SEARCH METHODS

A previous version of this review was published in 2014. In this update, we searched CENTRAL, MEDLINE, Embase, five other databases, and one trials register up to February 2022, together with reference checking and contact with study authors to identify additional studies.

SELECTION CRITERIA

Randomized controlled trials (RCTs) of preventive zinc supplementation in children aged 6 months to 12 years compared with no intervention, a placebo, or a waiting list control. We excluded hospitalized children and children with chronic diseases or conditions. We excluded food fortification or intake, sprinkles, and therapeutic interventions.

DATA COLLECTION AND ANALYSIS

Two review authors screened studies, extracted data, and assessed the risk of bias. We contacted study authors for missing information and used GRADE to assess the certainty of evidence. The primary outcomes of this review were all-cause mortality; and cause-specific mortality, due to all-cause diarrhea, lower respiratory tract infection (LRTI, including pneumonia), and malaria. We also collected information on a number of secondary outcomes, such as those related to diarrhea and LRTI morbidity, growth outcomes and serum levels of micronutrients, and adverse events.

MAIN RESULTS

We included 16 new studies in this review, resulting in a total of 96 RCTs with 219,584 eligible participants. The included studies were conducted in 34 countries; 87 of them in low- or middle-income countries. Most of the children included in this review were under five years of age. The intervention was delivered most commonly in the form of syrup as zinc sulfate, and the most common dose was between 10 mg and 15 mg daily. The median duration of follow-up was 26 weeks. We did not consider that the evidence for the key analyses of morbidity and mortality outcomes was affected by risk of bias. High-certainty evidence showed little to no difference in all-cause mortality with preventive zinc supplementation compared to no zinc (risk ratio (RR) 0.93, 95% confidence interval (CI) 0.84 to 1.03; 16 studies, 17 comparisons, 143,474 participants). Moderate-certainty evidence showed that preventive zinc supplementation compared to no zinc likely results in little to no difference in mortality due to all-cause diarrhea (RR 0.95, 95% CI 0.69 to 1.31; 4 studies, 132,321 participants); but probably reduces mortality due to LRTI (RR 0.86, 95% CI 0.64 to 1.15; 3 studies, 132,063 participants) and mortality due to malaria (RR 0.90, 95% CI 0.77 to 1.06; 2 studies, 42,818 participants); however, the confidence intervals around the summary estimates for these outcomes were wide, and we could not rule out a possibility of increased risk of mortality. Preventive zinc supplementation likely reduces the incidence of all-cause diarrhea (RR 0.91, 95% CI 0.90 to 0.93; 39 studies, 19,468 participants; moderate-certainty evidence) but results in little to no difference in morbidity due to LRTI (RR 1.01, 95% CI 0.95 to 1.08; 19 studies, 10,555 participants; high-certainty evidence) compared to no zinc. There was moderate-certainty evidence that preventive zinc supplementation likely leads to a slight increase in height (standardized mean difference (SMD) 0.12, 95% CI 0.09 to 0.14; 74 studies, 20,720 participants). Zinc 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; 5 studies, 35,192 participants; high-certainty evidence). We report a number of other outcomes, including the effect of zinc supplementation on weight and serum markers such as zinc, hemoglobin, iron, copper, etc. We also performed a number of subgroup analyses and there was a consistent finding for a number of outcomes that co-supplementation of zinc with iron decreased the beneficial effect of zinc.

AUTHORS' CONCLUSIONS

Even though we included 16 new studies in this update, the overall conclusions of the review remain unchanged. Zinc supplementation might help prevent episodes of diarrhea and improve growth slightly, particularly in children aged 6 months to 12 years of age. The benefits of preventive zinc supplementation may outweigh the harms in regions where the risk of zinc deficiency is relatively high.

Does Therapeutic Zinc Level of Supplementation for Diminutions of Acute Diarrheal Morbidity Varied in Public and Private Health Institutions in Ethiopia, Data from EDHS 2016?

Background

Supplementation of zinc is a therapeutic medication for under-five children diminution incidence, severity, duration, and intensity of acute diarrhea morbidity. Nevertheless, levels of therapeutic zinc supplementation varied across public and private health institutions in Ethiopia. Thus, this study was aimed at estimating the levels of therapeutic zinc supplementation and factors associated for intent to be utilized among caregivers with their dyads, data from Ethiopia Demographic and Health Survey (EDHS 2016).

Methods

The data used were from a secondary analysis of the Ethiopia Demographic and Health Survey in 2016 (EDHS). Overall, 1090 under-five children with acute diarrheal cases of two weeks before the EDHS 2016 were included. After cleaning, editing, and coding variables, the result was presented with frequency, tables, and graphs. Bivariable and multivariable logistic regression was conducted to identify and determine factors associated after zinc is prescribed for utilizations by caregivers.

Result

The mean (±SD) age of participant children was found to be 36.4(±7.07) month. The overall levels of therapeutic zinc supplementation were 38.7% (95% CI: 35.8, 41.6) in public (29.08%) and private 138 (12.66%), respectively. The prescribed therapeutic zinc was influenced for utilization through maternal educational status (AOR = 2.55; 95% CI: 1.95, 3.47; P = 0.001), availability of health insurance (AOR = 10.7; 95% CI: 7.2, 16; P = 0.001), media exposure status (AOR = 2.1; 95% CI: 1.7, 3.6; P = 0.001).

Conclusion

More than twofold time therapeutic zinc was prescribed in public than in private health institutions. Health care workers should be encouraged both in public and private health institutions for zinc prescription.

Zinc as a Neuroprotective Nutrient for COVID-19-Related Neuropsychiatric Manifestations: A Literature Review

The outbreak of the pandemic associated with Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2) led researchers to find new potential treatments, including nonpharmacological molecules such as zinc (Zn2+). Specifically, the use of Zn2+ as a therapy for SARS-CoV-2 infection is based on several findings: 1) the possible role of the anti-inflammatory activity of Zn2+ on the aberrant inflammatory response triggered by COronaVIrus Disease 19 (COVID-19), 2) properties of Zn2+ in modulating the competitive balance between the host and the invading pathogens, and 3) the antiviral activity of Zn2+ on a number of pathogens, including coronaviruses. Furthermore, Zn2+ has been found to play a central role in regulating brain functioning and many disorders have been associated with Zn2+ deficiency, including neurodegenerative diseases, psychiatric disorders, and brain injuries. Within this context, we carried out a narrative review to provide an overview of the evidence relating to the effects of Zn2+ on the immune and nervous systems, and the therapeutic use of such micronutrients in both neurological and infective disorders, with the final goal of elucidating the possible use of Zn2+ as a preventive or therapeutic intervention in COVID-19. Overall, the results from the available evidence showed that, owing to its neuroprotective properties, Zn2+ supplementation could be effective not only on COVID-19-related symptoms but also on virus replication, as well as on COVID-19-related inflammation and neurological damage. However, further clinical trials evaluating the efficacy of Zn2+ as a nonpharmacological treatment of COVID-19 are required to achieve an overall improvement in outcome and prognosis.

Enteral zinc supplementation for prevention of morbidity and mortality in preterm neonates

BACKGROUND

Preterm and low birth weight infants are born with low stores in zinc, which is a vital trace element for growth, cell differentiation and immune function. Preterm infants are at risk of zinc deficiency during the postnatal period of rapid growth. Systematic reviews in the older paediatric population have previously shown that zinc supplementation potentially improves growth and positively influences the course of infectious diseases. In paediatric reviews, the effect of zinc supplementation was most pronounced in those with low nutritional status, which is why the intervention could also benefit preterm infants typically born with low zinc stores and decreased immunity.

OBJECTIVES

To determine whether enteral zinc supplementation, compared with placebo or no supplementation, affects important outcomes in preterm infants, including death, neurodevelopment, common morbidities and growth.

SEARCH METHODS

Our searches are up-to-date to 20 February 2020. For the first search, we used the standard search strategy of Cochrane Neonatal to search the Cochrane Central Register of Controlled Trials (CENTRAL 2017, Issue 8), MEDLINE via PubMed (1966 to 29 September 2017), Embase (1980 to 29 September 2017), and CINAHL (1982 to 29 September 2017). We also searched clinical trials databases, conference proceedings, and the reference lists of retrieved articles for randomised controlled trials (RCTs) and quasi-RCTs. We ran an updated search from 1 January 2017 to 20 February 2020 in the following databases: CENTRAL via CRS Web, MEDLINE via Ovid, and CINAHL via EBSCOhost.

SELECTION CRITERIA

We included RCTs and quasi-RCTs that compared enteral zinc supplementation versus placebo or no supplementation in preterm infants (gestational age < 37 weeks), and low birth weight babies (birth weight < 2500 grams), at any time during their hospital admission after birth. We included zinc supplementation in any formulation, regimen, or dose administered via the enteral route. We excluded infants who underwent gastrointestinal (GI) surgery during their initial hospital stay, or had a GI malformation or another condition accompanied by abnormal losses of GI juices, which contain high levels of zinc (including, but not limited to, stomas, fistulas, and malabsorptive diarrhoea).

DATA COLLECTION AND ANALYSIS

We used the standard methods of Cochrane Neonatal. Two review authors separately screened abstracts, evaluated trial quality and extracted data. We synthesised effect estimates using risk ratios (RR), risk differences (RD), and standardised mean differences (SMD). Our primary outcomes of interest were all-cause mortality and neurodevelopmental disability. We used the GRADE approach to assess the certainty of evidence.

MAIN RESULTS

We included five trials with a total of 482 preterm infants; there was one ongoing trial. The five included trials were generally small, but of good methodological quality. Enteral zinc supplementation compared to no zinc supplementation Enteral zinc supplementation started in hospitalised preterm infants may decrease all-cause mortality (between start of intervention and end of follow-up period) (RR 0.55, 95% CI 0.31 to 0.97; 3 studies, 345 infants; low-certainty evidence). No data were available on long-term neurodevelopmental outcomes at 18 to 24 months of (post-term) age. Enteral zinc supplementation may have little or no effect on common morbidities such as bronchopulmonary dysplasia (RR 0.66, 95% CI 0.31 to 1.40, 1 study, 193 infants; low-certainty evidence), retinopathy of prematurity (RR 0.14, 95% CI 0.01 to 2.70, 1 study, 193 infants; low-certainty evidence), bacterial sepsis (RR 1.11, 95% CI 0.60 to 2.04, 2 studies, 293 infants; moderate-certainty evidence), or necrotising enterocolitis (RR 0.08, 95% CI 0.00 to 1.33, 1 study, 193 infants; low-certainty evidence). The intervention probably improves weight gain (SMD 0.46, 95% CI 0.28 to 0.64; 5 studies, 481 infants; moderate-certainty evidence); and may slightly improve linear growth (SMD 0.75, 95% CI 0.36 to 1.14, 3 studies, 289 infants; low-certainty evidence), but may have little or no effect on head growth (SMD 0.21, 95% CI -0.02 to 0.44, 3 studies, 289 infants; moderate-certainty evidence).

AUTHORS' CONCLUSIONS

Enteral supplementation of zinc in preterm infants compared to no supplementation or placebo may moderately decrease mortality and probably improve short-term weight gain and linear growth, but may have little or no effect on common morbidities of prematurity. There are no data to assess the effect of zinc supplementation on long-term neurodevelopment.

Potential health benefits of zinc supplementation for the management of COVID-19 pandemic

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the etiological agent for the Coronavirus Disease 2019 (COVID-19). The COVID-19 pandemic has created unimaginable and unprecedented global health crisis. Since the outbreak of COVID-19, millions of dollars have been spent, hospitalization overstretched with increasing morbidity and mortality. All these have resulted in unprecedented global economic catastrophe. Several drugs and vaccines are currently being evaluated, tested, and administered in the frantic efforts to stem the dire consequences of COVID-19 with varying degrees of successes. Zinc possesses potential health benefits against COVID-19 pandemic by improving immune response, minimizing infection and inflammation, preventing lung injury, inhibiting viral replication through the interference of the viral genome transcription, protein translation, attachment, and host infectivity. However, this review focuses on the various mechanisms of action of zinc and its supplementation as adjuvant for vaccines an effective therapeutic regimen in the management of the ravaging COVID-19 pandemic. PRACTICAL APPLICATIONS: The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the etiological agent for the Coronavirus Disease 2019 (COVID-19), has brought unprecedented untold hardship to both developing and developed countries. The global race for vaccine development against COVID-19 continues with success in sight with attendant increasing hospitalization, morbidity, and mortality. Available drugs with anti-inflammatory actions have become alternative to stem the tide of COVID-19 with attendant global financial crises. However, Zinc is known to modulate several physiological functions including intracellular signaling, enzyme function, gustation, and olfaction, as well as reproductive, skeletal, neuronal, and cardiovascular systems. Hence, achieving a significant therapeutic approach against COVID-19 could imply the use of zinc as a supplement together with available drugs and vaccines waiting for emergency authorization to win the battle of COVID-19. Together, it becomes innovative and creative to supplement zinc with currently available drugs and vaccines.

Role of Zinc Supplementation in the Improvement of Acute Respiratory Infections among Iranian Children: A Systematic Review

BACKGROUND

Respiratory infectious disease is considered as one of the most serious problems among children in developing countries. The importance of zinc in the improvement of respiratory disease has been indicated. However, there are some unanswered questions and uncertainty. This systematic review aimed at assessing the therapeutic benefits of zinc supplementation on respiratory infections of Iranian children.

MATERIALS AND METHODS

Databases, such as PubMed, Scopus, Embase, Magiran, and IranDoc, were searched for randomized controlled trials published from January 1998 to December 2017 on Zinc supplementation for the treatment or improvement of acute respiratory disease among Iranian children, during March 2018. Studies were screened according to the PICO framework, and irrelevant studies were excluded.

RESULTS

A total of 5 studies conducted on 522 children were included in this review. Except for one study, others had indicated the beneficial effect of zinc supplement on improving signs and symptoms of respiratory infectious disease and earlier discharge from the hospital.

CONCLUSION

Although studies on the efficacy of zinc on respiratory infectious disease of children in Iran have not widely considered and more studies should be conducted, all published articles (except for one of them) had indicated the effectiveness of zinc supplementation on respiratory infections among children. Other criteria, such as age, gender, birth weight, diet, and type of respiratory infections, should be considered during zinc therapy. Controlling these confounding variables and measuring the level of blood zinc are necessary to understand how much zinc should be prescribed for respiratory treatment of children.

Effectiveness of zinc supplementation on diarrhea and average daily gain in pre-weaned dairy calves: A double-blind, block-randomized, placebo-controlled clinical trial

The objective of this clinical trial was to evaluate the effectiveness of zinc supplementation on diarrhea and average daily weight gain (ADG) in pre-weaned dairy calves. A total of 1,482 healthy Holstein heifer and bull calves from a large California dairy were enrolled at 24 to 48 hours of age until hutch exit at approximately 90 days of age. Calves were block-randomized by time to one of three treatments: 1) placebo, 2) zinc methionine (ZM), or 3) zinc sulfate (ZS) administered in milk once daily for 14 days. Serum total protein at enrollment and body weight at birth, treatment end, and hutch exit were measured. Fecal consistency was assessed daily for 28 days post-enrollment. For a random sample of 127 calves, serum zinc concentrations before and after treatment and a fecal antigen ELISA at diarrhea start and resolution for Escherichia coli K99, rotavirus, coronavirus, and Cryptosporidium parvum were performed. Linear regression showed that ZM-treated bull calves had 22 g increased ADG compared to placebo-treated bulls (P = 0.042). ZM-treated heifers had 9 g decreased ADG compared to placebo-treated heifers (P = 0.037), after adjusting for average birth weight. Sex-stratified models showed that high birth weight heifers treated with ZM gained more than placebo-treated heifers of the same birth weight, which suggests a dose-response effect rather than a true sex-specific effect of ZM on ADG. Cox regression showed that ZM and ZS-treated calves had a 14.7% (P = 0.015) and 13.9% (P = 0.022) reduced hazard of diarrhea, respectively, compared to placebo-treated calves. Calves supplemented for at least the first five days of diarrhea with ZM and ZS had a 21.4% (P = 0.027) and 13.0% (P = 0.040) increased hazard of cure from diarrhea, respectively, compared to placebo-treated calves. Logistic regression showed that the odds of microbiological cure at diarrhea resolution for rotavirus, C. parvum, or any single fecal pathogen was not different between treatment groups. Zinc supplementation delayed diarrhea and expedited diarrhea recovery in pre-weaned calves. Additionally, zinc improved weight gain differentially in bulls compared to heifers, indicating a research need for sex-specific dosing.

An agonist of a zinc-sensing receptor GPR39 enhances tight junction assembly in intestinal epithelial cells via an AMPK-dependent mechanism

Intestinal barrier function depends on integrity of tight junctions, which serve as barriers to transepithelial influx of noxious substances/microorganisms from gut lumen. The G-protein coupled receptor 39 (GPR39) is a zinc-sensing receptor, which is expressed in several cell types including intestinal epithelial cells (IECs). The main objective of this study was to investigate the effect of GPR39 activation on tight junction assembly in IECs. Treatment with TC-G 1008 (1 μM -10 μM), a GPR39 agonist, and zinc (10 μM -100 μM) increased tight junction assembly in T84 cells. This effect was suppressed by pretreatment with compound C, an inhibitor of AMP-activated protein kinase (AMPK). In addition, western blot analysis revealed that treatment with TC-G 1008 induced AMPK activation in time- and concentration-dependent manners. Interestingly, inhibitors of phospholipase C (PLC) and calcium/calmodulin-dependent protein kinase kinase β (CaMKKβ) abrogated the effect of TC-G 1008 on inducing AMPK activation, tight junction assembly and zonula occludens-1 re-organization. Collectively, this study reveals a novel role of GPR39 in enhancing tight junction assembly in IECs via PLC-CaMKKβ-AMPK pathways. GPR39 agonists may be beneficial in the treatment of diseases associated impaired intestinal barrier function.

Drug-development concepts as guides for optimizing clinical trials of supplemental zinc for populations at risk of deficiency or diarrhea

Studies on the efficacy of zinc supplementation for treatment or prevention of diarrhea have shown an inconsistent effect in populations at risk for zinc deficiency. Unlike drugs, which have no preexisting presence in the body, endogenous zinc must be assessed pharmacokinetically by isotope tracer studies. Although such methods have produced much data, very few studies have estimated the dose and the timing of dosing of zinc supplementation. This review examines drug kinetics used to establish the best dose, the timing of such doses, and the mechanism of action through pharmacodynamic markers and applies them, where possible, to zinc supplements. The findings reveal that little is known, especially in children at highest risk of zinc deficiency. Key data missing to inform proper dosing, whether for treatment of disease or for preventive nutrient supplementation, are noted. Addressing these uncertainties could improve study design, leading to future studies of zinc supplements that might be of greater benefit.

From guidelines to local realities: evaluation of oral rehydration therapy and zinc supplementation in Guatemala

Objective. Diarrhea remains a leading cause of morbidity and mortality for children in low- and middle-income countries throughout the Americas. The World Health Organization (WHO) has developed guidelines on incorporating zinc supplementation (ZS) with traditional oral rehydration therapy (ORT) in order to shorten the duration of diarrheal episodes and to reduce poor health outcomes. Guatemala adopted these guidelines in 2011, but they have not yet been fully implemented at the community level. The objectives of this study were: (1) to co-design an ORT/ZS training program for community members with local health promoters that is appropriate to the local context and (2) to understand how attitudes and behaviors of community members changed after receiving training from the study promoters.

Methods. In an observational study, community health promoters in rural Guatemala were trained according to WHO guidelines, and they worked collaboratively with the study team to develop a training curriculum to implement in their community. Community-based surveys, interviews, and focus group discussions were used to assess acceptability, accessibility, and availability of oral rehydration therapy and zinc supplementation.

Results. Use of ORT increased from 63% to 95% among community members following training by local health promoters. Satisfaction with the service offered by health promoters increased from 63% to 90% amongst community members trained by the study promoters. However, knowledge and use of zinc supplementation remained low, which was attributable to unavailability of zinc in the study community.

Conclusions. Use of trained community health promoters is an effective way to translate WHO guidelines to local contexts and overcome sociocultural barriers to care. However, the health system’s structure must support availability of essential medicines in order to effectively implement those guidelines.

Zinc for Acute Diarrhea and Amoxicillin for Pneumonia, Do They Work? : Delivered at the AIIMS, IJP Excellence Award for the year 2013 on 7th September 2014

Acute diarrhea and pneumonia are the two largest killers of under-five children in the world. Zinc, used in management of acute diarrhea and Amoxicillin, used in community acquired pneumonia, feature in the list of 13 Life Saving Commodities for Women's and Children Health by the UN Commission. Zinc has caught wide scientific attention for the conceptual promise it has to offer for prevention, control and treatment of acute diarrhea. This presentation focuses on author's research on the mechanisms by which zinc might contribute to the pathogenesis of acute diarrhea and the degree of success achieved in diarrhea control and treatment by zinc supplementation including its impact on mortality. However, emerging evidence in terms of controlled studies in humans beckons a more complete understanding of the mechanistic basis for zinc supplementation. Current evidence indicates that studies specifically addressing the variability in response to zinc supplementation need to be undertaken to better comprehend these mechanisms. Similarly, the author presented her research that examined the role of oral amoxicillin in community management of severe pneumonia in children and the need to assess its universal efficacy in all children with severe pneumonia.

The potential for zinc stable isotope techniques and modelling to determine optimal zinc supplementation

It is well recognised that zinc deficiency is a major global public health issue, particularly in young children in low-income countries with diarrhoea and environmental enteropathy. Zinc supplementation is regarded as a powerful tool to correct zinc deficiency as well as to treat a variety of physiologic and pathologic conditions. However, the dose and frequency of its use as well as the choice of zinc salt are not clearly defined regardless of whether it is used to treat a disease or correct a nutritional deficiency. We discuss the application of zinc stable isotope tracer techniques to assess zinc physiology, metabolism and homeostasis and how these can address knowledge gaps in zinc supplementation pharmacokinetics. This may help to resolve optimal dose, frequency, length of administration, timing of delivery to food intake and choice of zinc compound. It appears that long-term preventive supplementation can be administered much less frequently than daily but more research needs to be undertaken to better understand how best to intervene with zinc in children at risk of zinc deficiency. Stable isotope techniques, linked with saturation response and compartmental modelling, also have the potential to assist in the continued search for simple markers of zinc status in health, malnutrition and disease.

Rapid normalization of vitamin D levels: a meta-analysis

BACKGROUND

Vitamin D deficiency may represent a modifiable risk factor to improve outcome in severe illness. The efficacy of high-dose regimens in rapid normalization of vitamin D levels is uncertain.

METHODS

We conducted a systematic review of pediatric clinical trials administering high-dose vitamin D to evaluate 25-hydroxyvitamin D (25[OH]D) response and characteristics associated with final 25(OH)D levels by using Medline, Embase, and the Cochrane Central Register of Controlled Trials, including reference lists of systematic reviews and eligible publications. Uncontrolled and controlled trials reporting 25(OH)D levels after high-dose (≥1000 IU) ergocalciferol or cholecalciferol were selected. Two reviewers independently extracted and verified predefined data fields.

RESULTS

We identified 88 eligible full-text articles. Two of 6 studies that administered daily doses approximating the Institute of Medicine's Tolerable Upper Intake Level (1000-4000 IU) to vitamin D-deficient populations achieved group 25(OH)D levels >75 nmol/L within 1 month. Nine of 10 studies evaluating loading therapy (>50 000 IU) achieved group 25(OH)D levels >75 nmol/L. In meta-regression, baseline 25(OH)D, regimen type, dose, age, and time factors were associated with final 25(OH)D levels. Adverse event analysis identified increased hypercalcemia risk with doses >400 000 IU, but no increased hypercalcemia or hypercalciuria with loading doses <400 000 IU (or 10 000 IU/kg). Few studies in adolescents evaluated loading dose regimens >300 000 IU.

CONCLUSIONS

Rapid normalization of vitamin D levels is best achieved by using loading therapy that considers disease status, baseline 25(OH)D, and age (or weight). Loading doses >300 000 IU should be avoided until trials are conducted to better evaluate risk and benefit.

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 deficiency in children with environmental enteropathy-development of new strategies: report from an expert workshop

Zinc deficiency is a major cause of childhood morbidity and mortality. The WHO/UNICEF strategy for zinc supplementation as adjunctive therapy for diarrhea is poorly implemented. A conference of experts in zinc nutrition and gastrointestinal disorders was convened to consider approaches that might complement the current recommendation and what research was needed to develop these approaches. Several key points were identified. The design of novel zinc interventions would be facilitated by a better understanding of how disturbed gut function, such as environmental (or tropical) enteropathy, affects zinc absorption, losses, and homeostasis. Because only 10% of zinc stores are able to be rapidly turned over, and appear to be rapidly depleted by acute intestinal illness, they are probably best maintained by complementary regular supplementation in a primary prevention strategy rather than secondary prevention triggered by acute diarrhea. The assessment of zinc status is challenging and complex without simple, validated measures to facilitate field testing of novel interventions. Zinc bioavailability may be a crucial factor in the success of primary prevention strategies, and a range of options, all still inadequately explored, might be valuable in improving zinc nutrition. Some therapeutic actions of zinc on diarrhea seem attributable to pharmacologic effects, whereas others are related to the reversal of deficiency (ie, nutritional). The distinction between these 2 mechanisms cannot be clarified given the insensitivity of serum zinc to identify subclinical deficiency states. Why zinc seems to be less effective than expected at all ages, and ineffective for secondary prevention of diarrhea in children <12 mo of age, remains unclear. It was concluded that a reframing of the current recommendation is warranted with consideration of how to better optimize and deliver zinc and whether to provide a complementary public health primary prevention zinc strategy. This requires careful consideration of the zinc product to be used as well as strategies for its delivery.

Evaluating the cost-effectiveness of preventive zinc supplementation

BACKGROUND

Even though the WHO currently recommends zinc for diarrhea management, no consensus has been reached with respect to routine distribution of zinc for preventive reasons. We reviewed the health impact of preventive zinc interventions, and evaluated the relative cost effectiveness of currently feasible interventions.

METHODS

Using the latest relative risk estimates reported in the literature, we parameterized a health impact model, and calculated the expected benefits of zinc supplementation in a representative low-income country. We then computed the cost and cost-effectiveness for three delivery mechanisms: the direct distribution of zinc supplements, the distribution of micronutrient biscuits including zinc, and the distribution of zinc through water filtration systems.

RESULTS

Combining all health outcomes and impact estimates, we find that systematic zinc supplementation among children of ages one to five would avert 1.423 DALYs per 100 households and year in least developed countries. The estimated cost per DALY is US$ 606 for pill supplementation, US$ 1211 for micronutrient biscuits, and US$ 879 per DALY saved for water filtration systems.

CONCLUSIONS

Preventive zinc supplementation to children of ages 1-5 appears to be a highly cost-effective intervention in typical developing country settings. More research will be needed to determine the most effective mechanism to deliver zinc to this target population.

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.

Diarrhea among children in developing countries

Diarrhea continues to stand among the most important causes of global morbidity and mortality in children under 5 years of age. Although the introduction of oral rehydration and other case-management strategies have reduced acute diarrhea fatalities, many of the survivors develop persistent diarrhea and/or deficiencies of growth and cognition. Thus understanding the true global burden of diarrhea requires attention to acute diarrhea as well is its sequelae. To understand the etiology of moderate to severe diarrhea among children in high mortality areas of sub-Saharan Africa and south Asia we performed a comprehensive case-control study of children under 5 years of age at seven sites. Each site employed an identical case-control study design and each utilized a uniform comprehensive set of microbiological assays to identify the likely bacterial, viral and protozoal etiologies. Results of the studies will inform diarrhea prevention and management efforts worldwide.

Promoting appropriate management of diarrhea: a systematic review of literature for advocacy and action: UNICEF-PHFI series on newborn and child health, India

BACKGROUND

Scaling up of evidence-based management and prevention of childhood diarrhea is a public health priority in India, and necessitates robust literature review, for advocacy and action.

OBJECTIVE

To identify, synthesize and summarize current evidence to guide scaling up of management of diarrhea among under-five children in India, and identify existing knowledge gaps.

METHODS

A set of questions pertaining to the management (prevention, treatment, and control) of childhood diarrhea was identified through a consultative process. A modified systematic review process developed a priori was used to identify, synthesize and summarize, research evidence and operational information, pertaining to the problem in India. Areas with limited or no evidence were identified as knowledge gaps.

RESULTS

Childhood diarrhea is a significant public health problem in India; the point (two weeks) prevalence is 9 to 20%. Diarrhea accounts for 14% of the total deaths in under-five children in India. Infants aged 6 to 24 months are at the highest risk of diarrhea. There is a lack of robust nation-wide data on etiology; rotavirus and diarrheogenic E.coli are the most common organisms identified. The current National Guidelines are sufficient for case-management of childhood diarrhea. Exclusive breastfeeding, handwashing and point of use water treatment are effective strategies for prevention of all-cause diarrhea; rotavirus vaccines are efficacious to prevent rotavirus specific diarrhea. ORS and zinc are the mainstay of management during an episode of childhood diarrhea but have low coverage in India due to policy and programmatic barriers, whereas indiscriminate use of antibiotics and other drugs is common. Zinc therapy given during diarrhea can be upscaled through existing infrastructure is introducing the training component and information, education and communication activities.

CONCLUSION

This systematic review summarizes current evidence on childhood diarrhea and provides evidence to inform child health programs in India.

Therapeutic zinc and copper supplementation in acute diarrhea does not influence short-term morbidity and growth: double-blind randomized controlled trial

Our objective was to evaluate the effect of zinc and copper supplementation in acute diarrhea on morbidity and growth during 12 weeks of follow-up. In a double-blind randomized controlled clinical trial of 724 children aged 6-59 months, none of the 11 evaluated outcomes showed significant association with zinc or zinc and copper supplementation. Thus, therapeutic zinc supplementation may not always yield short-term -benefits.

Nutritional consequences of chronic diarrhoea

There is an undeniable link between gastrointestinal disorders and malnutrition. Chronic diarrhoea is one of the most common gastrointestinal conditions that can impact a patient's nutritional status. The nutritional consequences will depend on the cause of the diarrhoea as well as the location and extent of gastrointestinal involvement. In general, malabsorption plays a central role in the interaction between malnutrition and chronic diarrhoea. Malabsorption can result in both nutritional deficits and diarrhoea. With severe malnutrition, chronic diarrhoea can persist due to impaired immune function and poor mucosal recovery. Food intolerance and an inappropriate diet in the setting of malabsorption may also contribute to chronic diarrhoea. Patients may attribute their gastrointestinal symptoms to specific dietary intake, which can lead to self-imposed indiscriminate dietary restrictions. Therefore, disease-specific treatment in conjunction with appropriate nutritional counselling and intervention is recommended in the prevention and treatment of malnutrition in patients with chronic diarrhoea. Specialized nutritional support through enteral or parenteral administration may be required to treat severe caloric and micronutrient deficiencies. In this review, we aim to summarize the mechanism, diagnosis, and treatment of the nutritional consequences of chronic diarrhoea.

Zinc in well water and infant mortality in bangladesh: a report from gonoshasthaya kendra

Zinc supplementation reduces the duration, severity and recurrence of diarrhoea in young children. This study examines whether zinc, found naturally in drinking water, reduced infant deaths from diarrhoea in rural Bangladesh. Information was compiled for births over two calendar years with follow-up for deaths within one year of birth. The study included 29,744 live births and 934 deaths in some 600 villages under the care of Gonoshasthaya Kendra (GK), grouped into 15 health centre regions within 12 upazillas. Individual matching of death to birth data was not possible, but information on exposures through well water and on potential confounders was available for each upazilla. Average concentration of zinc in well water, reported by the British Geological Survey, was grouped into high (>0.07 mg/L), moderate (0.020–0.070 mg/L) and low (<0.020 mg/L) concentrations. Odds ratios (OR) were calculated for zinc by age and cause of death. Zinc concentration was unrelated to all-cause mortality but a decrease in deaths from diarrhoea (N = 50) was seen in areas with high zinc (OR = 0.30; 95% CI 0.13–0.69). No relation to diarrhoeal deaths was found with other well contaminants (arsenic, manganese) having accounted for zinc. Upazillas with a high proportion of women without education had higher rates of death from diarrhea, but the decrease in risk with high zinc remained (OR adjusted = 0.41; 95% CI 0.20–0.84). It is concluded that exposure to zinc through drinking water may reduce risk of diarrhoeal deaths.