Galvanizing action: conclusions and next steps for mainstreaming zinc interventions in public health programs

Mechanistic Impact of Zinc Deficiency in Human Development

Zinc (Zn) deficiency in humans is an emerging global health issue affecting approximately two billion people across the globe. The situation prevails due to the intake of Zn deficient grains and vegetables worldwide. Clinical identification of Zn deficiency in humans remains problematic because the symptoms do not appear until impair the vital organs, such as the gastrointestinal track, central nervous system, immune system, skeletal, and nervous system. Lower Zn body levels are also responsible for multiple physiological disorders, such as apoptosis, organs destruction, DNA injuries, and oxidative damage to the cellular components through reactive oxygen species (ROS). The oxidative damage causes chronic inflammation lead toward several chronic diseases, such as heart diseases, cancers, alcohol-related malady, muscular contraction, and neuro-pathogenesis. The present review focused on the physiological and growth-related changes in humans under Zn deficient conditions, mechanisms adopted by the human body under Zn deficiency for the proper functioning of the body systems, and the importance of nutritional and nutraceutical approaches to overcome Zn deficiency in humans and concluded that the biofortified food is the best source of Zn as compared to the chemical supplementation to avoid their negative impacts on human.

Home fortification of foods with multiple micronutrient powders for health and nutrition in children under two years of age

BACKGROUND

Vitamin and mineral deficiencies, particularly those of iron, vitamin A, and zinc, affect more than two billion people worldwide. Young children are highly vulnerable because of rapid growth and inadequate dietary practices. Multiple micronutrient powders (MNPs) are single-dose packets containing multiple vitamins and minerals in powder form, which are mixed into any semi-solid food for children six months of age or older. The use of MNPs for home or point-of-use fortification of complementary foods has been proposed as an intervention for improving micronutrient intake in children under two years of age. In 2014, MNP interventions were implemented in 43 countries and reached over three million children. This review updates a previous Cochrane Review, which has become out-of-date.

OBJECTIVES

To assess the effects and safety of home (point-of-use) fortification of foods with MNPs on nutrition, health, and developmental outcomes in children under two years of age. For the purposes of this review, home fortification with MNP refers to the addition of powders containing vitamins and minerals to semi-solid foods immediately before consumption. This can be done at home or at any other place that meals are consumed (e.g. schools, refugee camps). For this reason, MNPs are also referred to as point-of-use fortification.

SEARCH METHODS

We searched the following databases up to July 2019: CENTRAL, MEDLINE, Embase, and eight other databases. We also searched four trials registers, contacted relevant organisations and authors of included studies to identify any ongoing or unpublished studies, and searched the reference lists of included studies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) and quasi-RCTs with individual randomisation or cluster-randomisation. Participants were infants and young children aged 6 to 23 months at the time of intervention, with no identified specific health problems. The intervention consisted of consumption of food fortified at the point of use with MNP formulated with at least iron, zinc, and vitamin A, compared with placebo, no intervention, or use of iron-containing supplements, which is standard practice.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed the eligibility of studies against the inclusion criteria, extracted data from included studies, and assessed the risk of bias of included studies. We reported categorical outcomes as risk ratios (RRs) or odds ratios (ORs), with 95% confidence intervals (CIs), and continuous outcomes as mean differences (MDs) and 95% CIs. We used the GRADE approach to assess the certainty of evidence.

MAIN RESULTS

We included 29 studies (33,147 children) conducted in low- and middle-income countries in Asia, Africa, Latin America, and the Caribbean, where anaemia is a public health problem. Twenty-six studies with 27,051 children contributed data. The interventions lasted between 2 and 44 months, and the powder formulations contained between 5 and 22 nutrients. Among the 26 studies contributing data, 24 studies (26,486 children) compared the use of MNP versus no intervention or placebo; the two remaining studies compared the use of MNP versus an iron-only supplement (iron drops) given daily. The main outcomes of interest were related to anaemia and iron status. We assessed most of the included studies at low risk of selection and attrition bias. We considered some studies to be at high risk of performance and detection bias due to lack of blinding. Most studies were funded by government programmes or foundations; only two were funded by industry. Home fortification with MNP, compared with no intervention or placebo, reduced the risk of anaemia in infants and young children by 18% (RR 0.82, 95% CI 0.76 to 0.90; 16 studies; 9927 children; moderate-certainty evidence) and iron deficiency by 53% (RR 0.47, 95% CI 0.39 to 0.56; 7 studies; 1634 children; high-certainty evidence). Children receiving MNP had higher haemoglobin concentrations (MD 2.74 g/L, 95% CI 1.95 to 3.53; 20 studies; 10,509 children; low-certainty evidence) and higher iron status (MD 12.93 μg/L, 95% CI 7.41 to 18.45; 7 studies; 2612 children; moderate-certainty evidence) at follow-up compared with children receiving the control intervention. We did not find an effect on weight-for-age (MD 0.02, 95% CI -0.03 to 0.07; 10 studies; 9287 children; moderate-certainty evidence). Few studies reported morbidity outcomes (three to five studies each outcome) and definitions varied, but MNP did not increase diarrhoea, upper respiratory infection, malaria, or all-cause morbidity. In comparison with daily iron supplementation, the use of MNP produced similar results for anaemia (RR 0.89, 95% CI 0.58 to 1.39; 1 study; 145 children; low-certainty evidence) and haemoglobin concentrations (MD -2.81 g/L, 95% CI -10.84 to 5.22; 2 studies; 278 children; very low-certainty evidence) but less diarrhoea (RR 0.52, 95% CI 0.38 to 0.72; 1 study; 262 children; low-certainty of evidence). However, given the limited quantity of data, these results should be interpreted cautiously. Reporting of death was infrequent, although no trials reported deaths attributable to the intervention. Information on side effects and morbidity, including malaria and diarrhoea, was scarce. It appears that use of MNP is efficacious among infants and young children aged 6 to 23 months who are living in settings with different prevalences of anaemia and malaria endemicity, regardless of intervention duration. MNP intake adherence was variable and in some cases comparable to that achieved in infants and young children receiving standard iron supplements as drops or syrups.

AUTHORS' CONCLUSIONS

Home fortification of foods with MNP is an effective intervention for reducing anaemia and iron deficiency in children younger than two years of age. Providing MNP is better than providing no intervention or placebo and may be comparable to using daily iron supplementation. The benefits of this intervention as a child survival strategy or for developmental outcomes are unclear. Further investigation of morbidity outcomes, including malaria and diarrhoea, is needed. MNP intake adherence was variable and in some cases comparable to that achieved in infants and young children receiving standard iron supplements as drops or syrups.

Comparison of two forms of daily preventive zinc supplementation versus therapeutic zinc supplementation for diarrhea on young children's physical growth and risk of infection: study design and rationale for a randomized controlled trial

Background

Zinc is an essential nutrient that is required for children’s normal growth and resistance to infections, including diarrhea and pneumonia, two major causes of child mortality. Daily or weekly preventive zinc supplementation has been shown to improve growth and reduce the risk of infection, while therapeutic zinc supplementation for 10–14 days is recommended for the treatment of diarrhea. The overall objective of the present study is to compare several regimens for delivering zinc to young children, both for the prevention of zinc deficiency and the treatment of diarrhea.

Methods

The present study is a community-based, randomized controlled trial in the Lao People’s Democratic Republic (PDR). Three thousand, four hundred children 6–23 months of age will be randomized to one of four intervention groups (daily preventive zinc dispersible tablet, daily preventive multiple micronutrient powder, therapeutic zinc dispersible tablet for diarrhea, or placebo control); interventions will be delivered for 9 months and outcomes measured at pre-determined intervals. Primary outcomes include physical growth (length and weight), diarrhea incidence, hemoglobin and micronutrient status, and innate and adaptive immune function. Secondary outcomes include mid-upper-arm circumference, neuro-behavioral development, hair cortisol concentrations, markers of intestinal inflammation and parasite burden. Incidence of adverse events and the modifying effects of inherited hemoglobin disorders and iron status on the response to the intervention will also be examined. We will estimate unadjusted effects and effects adjusted for selected baseline covariates using ANCOVA.

Discussion

Many countries are now rolling out large-scale programs to include therapeutic zinc supplementation in the treatment of childhood diarrhea, but few have established programs demonstrated to be effective in the prevention of zinc deficiency. This study will address how best to deliver supplemental zinc to prevent zinc deficiency and reduce the severity of diarrhea-related health complications.

Trial registration

Trial registration identifier (NCT02428647) ; Date of registration: April 29, 2015.

Education and micronutrient deficiencies: an ecological study exploring interactions between women's schooling and children's micronutrient status

Background

Formal education can be a nutrition-sensitive intervention that supports the scale-up and impact of nutrition-specific actions. Maternal education has long been linked to child survival, growth, and development while adult earnings and nutrition are tied to years in school as a child. However, less is known about the relationship between maternal education and the micronutrient status of children, women and the general population.

Methods

Using country-level data and an ecological study design, we explored the global associations between women’s educational attainment and: a) anemia and vitamin A deficiency (VAD) in children aged 6–59 months; b) anemia in non-pregnant women; and c) zinc deficiency, urinary iodine excretion (UIE), and the proportion of infants protected against iodine deficiency in the general population Cross-sectional relationships (2005–2013) were assessed using linear regression models.

Results

Percentage of women without schooling was negatively associated with all outcomes. Number of years of schooling among women was positively associated with all outcomes except for UIE and the proportion of infants protected against iodine deficiency. Income level was a significant effect modifier of the effect of years of women’s schooling on child anemia as well as of the proportion of women without formal education on zinc deficiency in the population. The relationship was strongest in low-income countries for child anemia, and was not significant in upper middle-income countries. For zinc deficiency, the relationship was not significant in low or lower middle income countries, which may suggest that a minimum threshold of resources needs to be reached before education can influence zinc status.

Conclusions

While relationships between maternal schooling and micronutrient outcomes vary around the globe, more schooling is generally linked to lower rates of deficiency. These findings draw policy-relevant connections between formal education and anemia and micronutrient status globally. It is necessary to examine the mechanisms through which this relationship may be working at both household and country level.

Electronic supplementary material

The online version of this article (10.1186/s12889-018-5312-1) contains supplementary material, which is available to authorized users.

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.

Brazilian studies on zinc deficiency and supplementation: emphasis on children

Abstract Objectives: to review the literature of studies developed in Brazil on zinc deficiency and the effects of supplementation. Methods: a literature review based on bibliographic research was carried out in SciELO, LILACS and MEDLINE/PUBMED databases. A total of 133 studies on zinc deficiency and 116 on the effects of supplementation were identified. Thirty-two articles, 16 of which were observational and 16 interventional, were analyzed. Results: the studies focused mainly on children (75.0% of the observational and 81.25% of the experimental studies). Biochemical deficiency of zinc in children presented great variability, from 0.0% to 74.3%, with expressive prevalence in most studies. Dietary inadequacy among children presented variability from 16.6% to 46.0%. Five from seven studies showed a positive effect of zinc supplementation on micronutrient nutritional status. Conclusions: there is evidence of zinc deficiency in children as a public health problem, preventable through micronutrient supplementation.

National Risk of Zinc Deficiency as Estimated by National Surveys

BACKGROUND

Information is needed on the national prevalence of zinc deficiency to guide program development and evaluation.

OBJECTIVE

To summarize results of national surveys that assessed plasma or serum zinc concentrations (PZC) and compare the prevalence of low PZC with other methods used to estimate countries' risk of zinc deficiency.

METHODS

National surveys that included PZC were identified through Internet searches and personal contacts. A survey was eligible if a nationally representative sampling scheme was used, PZC was analyzed, and the survey was implemented in a low- or middle-income country. Twenty surveys were eligible; 19 countries assessed PZC in young children and 14 in women of reproductive age.

RESULTS

In 13 of the 19 surveys, the prevalence of low PZC in children was >20%. Only Afghanistan, Azerbaijan, Nigeria, the Republic of Maldives, Sri Lanka, and China found a low prevalence of inadequate PZC among children. Some of these conclusions may be due to the lower than recommended cutoff that was used. Similarly, in 13 of 14 surveys, the prevalence of low PZC in women was >20%. Estimates of percentage population with inadequate dietary zinc intake based on food balance sheets underestimate the risk of zinc deficiency. The national stunting prevalence seems to be a useful proxy, as both indicators categorized countries similarly into high versus low risk of zinc deficiency, with some exceptions.

CONCLUSIONS

Results from 20 countries suggest that zinc deficiency is a public health concern in the majority of these countries and zinc intervention strategies should be considered.

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.

Home fortification of foods with multiple micronutrient powders for health and nutrition in children under two years of age (Review)

BACKGROUND

Vitamin and mineral deficiencies, particularly those of iron, vitamin A and zinc, affect more than two billion people worldwide. Young children are highly vulnerable because of rapid growth and inadequate dietary practices. Micronutrient powders (MNP) are single-dose packets containing multiple vitamins and minerals in powder form that can be sprinkled onto any semi-solid food.The use of MNP for home or point-of-use fortification of complementary foods has been proposed as an intervention for improving micronutrient intake in children under two years of age.

OBJECTIVES

To assess the effects and safety of home (point-of-use) fortification of foods with multiple micronutrient powders on nutritional, health and developmental outcomes in children under two years of age.

SEARCH METHODS

We searched the following databases in February 2011: Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library), MEDLINE (1948 to week 2 February 2011), EMBASE (1980 to Week 6 2011), CINAHL (1937 to current), CPCI-S (1990 to 19 February 2011), Science Citation Index (1970 to 19 February 2011), African Index Medicus (searched 23 February 2011), POPLINE (searched 21 February 2011), ClinicalTrials.gov (searched 23 February 2011), mRCT (searched 23 February 2011), and World Health Organization International Clinical Trials Registry Platform (ICTRP) (searched 23 February 2011). We also contacted relevant organisations (25 January 2011) for the identification of ongoing and unpublished studies.

SELECTION CRITERIA

We included randomised and quasi-randomised trials with either individual or cluster randomisation. Participants were children under the age of two years at the time of intervention, with no specific health problems. The intervention was consumption of food fortified at the point of use with multiple micronutrient powders formulated with at least iron, zinc and vitamin A compared with placebo, no intervention or the use of iron containing supplements, which is the standard practice.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed the eligibility of studies against the inclusion criteria, extracted data from included studies and assessed the risk of bias of the included studies.

MAIN RESULTS

We included eight trials (3748 participants) conducted in low income countries in Asia, Africa and the Caribbean, where anaemia is a public health problem. The interventions lasted between two and 12 months and the powder formulations contained between five and 15 nutrients. Six trials compared the use of MNP versus no intervention or a placebo and the other two compared the use of MNP versus daily iron drops. Most of the included trials were assessed as at low risk of bias. Home fortification with MNP reduced anaemia by 31% (six trials, RR 0.69; 95% CI 0.60 to 0.78) and iron deficiency by 51% (four trials, RR 0.49; 95% CI 0.35 to 0.67) in infants and young children when compared with no intervention or placebo, but we did not find an effect on growth. In comparison with daily iron supplementation, the use of MNP produced similar results on anaemia (one trial, RR 0.89; 95% CI 0.58 to 1.39) and haemoglobin concentrations (two trials, MD -2.36 g/L; 95% CI -10.30 to 5.58); however, given the limited amount of data these results should be interpreted cautiously. No deaths were reported in the trials and information on side effects and morbidity, including malaria, was scarce. It seems that the use of MNP is efficacious among infants and young children six to 23 months of age living in settings with different prevalences of anaemia and malaria endemicity, regardless of whether the intervention lasts two, six or 12 months or whether recipients are male or female.

AUTHORS' CONCLUSIONS

Home fortification of foods with multiple micronutrient powders is an effective intervention to reduce anaemia and iron deficiency in children six months to 23 months of age. The provision of MNP is better than no intervention or placebo and possibly comparable to commonly used daily iron supplementation. The benefits of this intervention as a child survival strategy or on developmental outcomes are unclear. Data on effects on malaria outcomes are lacking and further investigation of morbidity outcomes is needed. The micronutrient powders containing multiple nutrients are well accepted but adherence is variable and in some cases comparable to that achieved in infants and young children receiving standard iron supplements as drops or syrups.

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.

Comparison of the estimated cost-effectiveness of preventive and therapeutic zinc supplementation strategies for reducing child morbidity and mortality in sub-Saharan Africa

BACKGROUND

Zinc supplementation of young children in lower-income countries reduces morbidity from diarrhea and pneumonia and all-cause mortality, but the most cost-effective approach for distributing zinc supplements is unknown.

OBJECTIVE

To examine the potential impact of four possible strategies for delivering zinc supplements on disease prevention and deaths averted among children 6 to 59 months of age in sub-Saharan Africa.

METHODS

We analyzed different zinc supplementation strategies to assess their likely impact on morbidity and mortality of preschool children in sub-Saharan Africa and to estimate their possible costs.

RESULTS

Preventive zinc supplementation reduces diarrhea incidence by 27% among children 12 to 59 months of age, pneumonia incidence by 21% among children 6 to 59 months of age, and all-cause mortality by 18% among children 12 to 59 months of age. The likely average total program costs of zinc supplementation programs were estimated from the outlays of existing service delivery platforms, such as child health days, community-based nutrition programs, and clinic-based treatment of diarrhea, assuming different levels of coverage and target age ranges of children.

CONCLUSIONS

We found that the average total costs per life saved ranged from approximately US$462 to US$3,111, and the most cost-effective interventions were weekly or intermittent preventive zinc supplementation, because of the possibility of high coverage and fewer supplements required. Empirical data from zinc supplementation programs will be needed to confirm these estimates.

Position of the academy of nutrition and dietetics: nutrition security in developing nations: sustainable food, water, and health

It is the position of the Academy of Nutrition and Dietetics that all people should have consistent access to an appropriately nutritious diet of food and water, coupled with a sanitary environment, adequate health services, and care that ensure a healthy and active life for all household members. The Academy supports policies, systems, programs, and practices that work with developing nations to achieve nutrition security and self-sufficiency while being environmentally and economically sustainable. For nations to achieve nutrition security, all people must have access to a variety of nutritious foods and potable drinking water; knowledge, resources, and skills for healthy living; prevention, treatment, and care for diseases affecting nutrition status; and safety-net systems during crisis situations, such as natural disasters or deleterious social and political systems. More than 2 billion people are micronutrient deficient; 1.5 billion people are overweight or obese; 870 million people have inadequate food energy intake; and 783 million people lack potable drinking water. Adequate nutrient intake is a concern, independent of weight status. Although this article focuses on nutritional deficiencies in developing nations, global solutions for excesses and deficiencies need to be addressed. In an effort to achieve nutrition security, lifestyles, policies, and systems (eg, food, water, health, energy, education/knowledge, and economic) contributing to sustainable resource use, environmental management, health promotion, economic stability, and positive social environments are required. Food and nutrition practitioners can get involved in promoting and implementing effective and sustainable policies, systems, programs, and practices that support individual, community, and national efforts.

Effect of preventive supplementation with zinc and other micronutrients on non-malarial morbidity in Tanzanian pre-school children: a randomized trial

BACKGROUND

The efficacy of preventive zinc supplementation against diarrhea and respiratory illness may depend on simultaneous supplementation with other micronutrients. We aimed to assess the effect of supplementation with zinc and multiple micronutrients on diarrhea and other causes of non-malarial morbidity.

METHODS AND FINDINGS

Rural Tanzanian children (n = 612) aged 6-60 months and with height-for-age z-score < -1.5 SD were randomized to daily supplementation with zinc (10 mg) alone, multi-nutrients without zinc, multi-nutrients with zinc, or placebo. Children were followed for an average of 45 weeks. During follow-up, we recorded morbidity episodes. We found no evidence that concurrent supplementation with multi-nutrients influenced the magnitude of the effect of zinc on rates of diarrhea, respiratory illness, fever without localizing signs, or other illness (guardian-reported illness with symptoms involving skin, ears, eyes and abscesses, but excluding trauma or burns). Zinc supplementation reduced the hazard rate of diarrhea by 24% (4%-40%). By contrast, multi-nutrients seemed to increase this rate (HR; 95% CI: 1.19; 0.94-1.50), particularly in children with asymptomatic Giardia infection at baseline (2.03; 1.24-3.32). Zinc also protected against episodes of fever without localizing signs (0.75; 0.57-0.96), but we found no evidence that it reduced the overall number of clinic visits.

CONCLUSIONS

We found no evidence that the efficacy of zinc supplements in reducing diarrhea rates is enhanced by concurrent supplementation with other micronutrients. By reducing rates of fever without localizing signs, supplementation with zinc may reduce inappropriate drug use with anti-malarial medications and antibiotics.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00623857.

Effect of preventive supplementation with zinc and other micronutrients on non-malarial morbidity in Tanzanian pre-school children: a randomized trial

Background

The efficacy of preventive zinc supplementation against diarrhea and respiratory illness may depend on simultaneous supplementation with other micronutrients. We aimed to assess the effect of supplementation with zinc and multiple micronutrients on diarrhea and other causes of non-malarial morbidity.

Methods and Findings

Rural Tanzanian children (n = 612) aged 6–60 months and with height-for-age z-score < –1.5 SD were randomized to daily supplementation with zinc (10 mg) alone, multi-nutrients without zinc, multi-nutrients with zinc, or placebo. Children were followed for an average of 45 weeks. During follow-up, we recorded morbidity episodes. We found no evidence that concurrent supplementation with multi-nutrients influenced the magnitude of the effect of zinc on rates of diarrhea, respiratory illness, fever without localizing signs, or other illness (guardian-reported illness with symptoms involving skin, ears, eyes and abscesses, but excluding trauma or burns). Zinc supplementation reduced the hazard rate of diarrhea by 24% (4%–40%). By contrast, multi-nutrients seemed to increase this rate (HR; 95% CI: 1.19; 0.94–1.50), particularly in children with asymptomatic Giardia infection at baseline (2.03; 1.24–3.32). Zinc also protected against episodes of fever without localizing signs (0.75; 0.57–0.96), but we found no evidence that it reduced the overall number of clinic visits.

Conclusions

We found no evidence that the efficacy of zinc supplements in reducing diarrhea rates is enhanced by concurrent supplementation with other micronutrients. By reducing rates of fever without localizing signs, supplementation with zinc may reduce inappropriate drug use with anti-malarial medications and antibiotics.

Trial Registration

ClinicalTrials.gov NCT00623857

Home fortification of foods with multiple micronutrient powders for health and nutrition in children under two years of age

BACKGROUND

Vitamin and mineral deficiencies, particularly those of iron, vitamin A and zinc, affect more than two billion people worldwide. Young children are highly vulnerable because of rapid growth and inadequate dietary practices. Micronutrient powders (MNP) are single-dose packets containing multiple vitamins and minerals in powder form that can be sprinkled onto any semi-solid food.The use of MNP for home or point-of-use fortification of complementary foods has been proposed as an intervention for improving micronutrient intake in children under two years of age.

OBJECTIVES

To assess the effects and safety of home (point-of-use) fortification of foods with multiple micronutrient powders on nutritional, health and developmental outcomes in children under two years of age.

SEARCH STRATEGY

We searched the following databases in February 2011: Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library), MEDLINE (1948 to week 2 February 2011), EMBASE (1980 to Week 6 2011), CINAHL (1937 to current), CPCI-S (1990 to 19 February 2011), Science Citation Index (1970 to 19 February 2011), African Index Medicus (searched 23 February 2011), POPLINE (searched 21 February 2011), ClinicalTrials.gov (searched 23 February 2011), mRCT (searched 23 February 2011), and World Health Organization International Clinical Trials Registry Platform (ICTRP) (searched 23 February 2011). We also contacted relevant organisations (25 January 2011) for the identification of ongoing and unpublished studies.

SELECTION CRITERIA

We included randomised and quasi-randomised trials with either individual or cluster randomisation. Participants were children under the age of two years at the time of intervention, with no specific health problems. The intervention was consumption of food fortified at the point of use with multiple micronutrient powders formulated with at least iron, zinc and vitamin A compared with placebo, no intervention or the use of iron containing supplements, which is the standard practice.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed the eligibility of studies against the inclusion criteria, extracted data from included studies and assessed the risk of bias of the included studies.

MAIN RESULTS

We included eight trials (3748 participants) conducted in low income countries in Asia, Africa and the Caribbean, where anaemia is a public health problem. The interventions lasted between two and 12 months and the powder formulations contained between five and 15 nutrients. Six trials compared the use of MNP versus no intervention or a placebo and the other two compared the use of MNP versus daily iron drops. Most of the included trials were assessed as at low risk of bias.Home fortification with MNP reduced anaemia by 31% (six trials, RR 0.69; 95% CI 0.60 to 0.78) and iron deficiency by 51% (four trials, RR 0.49; 95% CI 0.35 to 0.67) in infants and young children when compared with no intervention or placebo, but we did not find an effect on growth.In comparison with daily iron supplementation, the use of MNP produced similar results on anaemia (one trial, RR 0.89; 95% CI 0.58 to 1.39) and haemoglobin concentrations (two trials, MD -2.36 g/L; 95% CI -10.30 to 5.58); however, given the limited amount of data these results should be interpreted cautiously.No deaths were reported in the trials and information on side effects and morbidity, including malaria, was scarce.It seems that the use of MNP is efficacious among infants and young children six to 23 months of age living in settings with different prevalences of anaemia and malaria endemicity, regardless of whether the intervention lasts two, six or 12 months or whether recipients are male or female.

AUTHORS' CONCLUSIONS

Home fortification of foods with multiple micronutrient powders is an effective intervention to reduce anaemia and iron deficiency in children six months to 23 months of age. The provision of MNP is better than no intervention or placebo and possibly comparable to commonly used daily iron supplementation. The benefits of this intervention as a child survival strategy or on developmental outcomes are unclear. Data on effects on malaria outcomes are lacking and further investigation of morbidity outcomes is needed. The micronutrient powders containing multiple nutrients are well accepted but adherence is variable and in some cases comparable to that achieved in infants and young children receiving standard iron supplements as drops or syrups.

Accelerating improvements in nutritional and health status of young children in the Sahel region of Sub-Saharan Africa: review of international guidelines on infant and young child feeding and nutrition

The United Nations Convention on the Rights of the Child holds governments responsible to ensure children's right to the highest attainable standard of health by providing breastfeeding support, and access to nutritious foods, appropriate health care, and clean drinking water. International experts have identified key child care practices and programmatic activities that are proven to be effective at reducing infant and young child undernutrition, morbidity, and mortality. Nevertheless, progress towards reducing the prevalence of undernutrition has been sporadic across countries of the Sahel sub-region of Sub-Saharan Africa. In view of this uneven progress, a working group of international agencies was convened to 'Reposition children's right to adequate nutrition in the Sahel.' The first step towards this goal was to organize a situational analysis of the legislative, research, and programmatic activities related to infant and young child nutrition (IYCN) in six countries of the sub-region: Burkina Faso, Chad, Mali, Mauritania, Niger, and Senegal. The purposes of this introductory paper are to review current information concerning the nutritional and health status of infants and young children in the Sahel and to summarize international guidelines on optimal IYCN practices. These guidelines were used in completing the above-mentioned situational analyses and encompass specific recommendations on: (i) breastfeeding (introduction within the first hour after birth, exclusivity to 6 months, continuation to at least 24 months); (ii) complementary feeding (introduction at 6 months, use of nutrient dense foods, adequate frequency and consistency, and responsive feeding); (iii) prevention and/or treatment of micronutrient deficiencies (vitamin A, zinc, iron and anaemia, and iodine); (iv) prevention and/or treatment of acute malnutrition; (v) feeding practices adapted to the maternal situation to reduce mother-to-child transmission of HIV; (vi) activities to ensure food security; and (vii) the promotion of hygienic practices concerning food preparation and storage and environmental sanitation. The following papers in this issue will present results of the situational analyses for the individual countries.

Essential role of vitamin C and zinc in child immunity and health

With the progressive elimination of dietary protein-energy deficits, deficiencies of micronutrients are emerging as the limiting factors in ensuring children's optimal health. Data from several countries in Asia and Latin America indicate that deficiencies of vitamin C and zinc continue to be at alarming levels. This article reviews the roles of vitamin C and zinc in supporting children's growth and development, with a particular focus on the complementary roles they play in supporting immune functions and combating infections. The contemporary relevance of vitamin C and zinc deficiency in the Asian and Latin American regions, both undergoing a rapid nutritional transition, are also discussed. Overall, there is increasing evidence that deficiency of vitamin C and zinc adversely affects the physical and mental growth of children and can impair their immune defences. Nutrition should be the main vehicle for providing these essential nutrients; however, supplementation can represent a valid support method, especially in developing regions.

Therapeutic value of zinc supplementation in acute and persistent diarrhea: a systematic review

BACKGROUND

For over a decade, the importance of zinc in the treatment of acute and persistent diarrhea has been recognized. In spite of recently published reviews, there remain several unanswered questions about the role of zinc supplementation in childhood diarrhea in the developing countries. Our study aimed to assess the therapeutic benefits of zinc supplementation in the treatment of acute or persistent diarrhea in children, and to examine the causes of any heterogeneity of response to zinc supplementation.

METHODS AND FINDINGS

EMBASE, MEDLINE and CINAHL databases were searched for published reviews and meta-analyses on the use of zinc supplementation for the prevention and treatment of childhood diarrhea. Additional RCTs published following the meta-analyses were also sought. The reviews and published RCTs were qualitatively mapped followed by updated random-effects meta-analyses, subgroup meta-analyses and meta-regression to quantify and characterize the role of zinc supplementation with diarrhea-related outcomes. We found that although there was evidence to support the use of zinc to treat diarrhea in children, there was significant unexplained heterogeneity across the studies for the effect of zinc supplementation in reducing important diarrhea outcomes. Zinc supplementation reduced the mean duration of diarrhea by 19.7% but had no effect on stool frequency or stool output, and increased the risk of vomiting. Our subgroup meta-analyses and meta-regression showed that age, stunting, breast-feeding and baseline zinc levels could not explain the heterogeneity associated with differential reduction in the mean diarrheal duration. However, the baseline zinc levels may not be representative of the existing zinc deficiency state.

CONCLUSIONS

Understanding the predictors of zinc efficacy including the role of diarrheal disease etiology on the response to zinc would help to identify the populations most likely to benefit from supplementation. To improve the programmatic use of zinc, further evaluations of the zinc salts used, the dose, the frequency and duration of supplementation, and its acceptability are required. The significant heterogeneity of responses to zinc suggests the need to revisit the strategy of universal zinc supplementation in the treatment children with acute diarrhea in developing countries.

The impact of common micronutrient deficiencies on iodine and thyroid metabolism: the evidence from human studies

Deficiencies of micronutrients are highly prevalent in low-income countries. Inadequate intake of iodine impairs thyroid function and results in a spectrum of disorders. Other common deficiencies of micronutrients such as iron, selenium, vitamin A, and possibly zinc may interact with iodine nutrition and thyroid function. Randomised controlled intervention trials in iodine- and iron-deficient populations have shown that providing iron along with iodine results in greater improvements in thyroid function and volume than providing iodine alone. Vitamin A supplementation given alone or in combination with iodised salt can have a beneficial impact on thyroid function and thyroid size. Despite numerous studies of the effect of selenium on iodine and thyroid metabolism in animals, most published randomised controlled intervention trials in human populations failed to confirm an impact of selenium supplementation on thyroid metabolism. Little evidence is available on interactions between iodine and zinc metabolism.

Zinc and micronutrient combinations to combat gastrointestinal inflammation

PURPOSE OF REVIEW

To examine current evidence for dietary supplementation with zinc and other micronutrients for primary prevention of multiple micronutrient deficiencies that are known to result from therapies used in the treatment of gastrointestinal inflammatory disorders.

RECENT FINDINGS

Epidemiological observations and clinical findings have strengthened the concept that both nutritional deficiencies and nutritional excesses impair the gastrointestinal response(s) and alter susceptibility to inflammation and other diseases. The interaction of micronutrient intake, biochemical indicators of nutritional status, and four specific gastrointestinal inflammation states are reviewed. These conditions include celiac disease and concomitant micronutrient deficiencies resulting from the sustained adherence to a gluten-free diet; micronutrient nutrition as an important determinant of immunity for two major types of inflammatory bowel disease: ulcerative colitis and Crohn's disease; and HIV/AIDS-related diarrhea and concomitant micronutrient deficiencies which may be exacerbated by the initiation of highly active antiretroviral therapy.

SUMMARY

For each inflammation 'state', enhancement of micronutrient status can improve immunocompetance and minimize therapeutic side-effects. The impact of single-micronutrient deficiencies on immune responses, and the possible impact of uncorrected micronutrient status are discussed.

Recent advances in knowledge of zinc nutrition and human health

Zinc deficiency increases the risk and severity of a variety of infections, restricts physical growth, and affects specific outcomes of pregnancy. Global recognition of the importance of zinc nutrition in public health has expanded dramatically in recent years, and more experience has accumulated on the design and implementation of zinc intervention programs. Therefore, the Steering Committee of the International Zinc Nutrition Consultative Group (IZiNCG) completed a second IZiNCG technical document that reexamines the latest information on the intervention strategies that have been developed to enhance zinc nutrition and control zinc deficiency. In particular, the document reviews the current evidence regarding preventive zinc supplementation and the role of zinc as adjunctive therapy for selected infections, zinc fortification, and dietary diversification or modification strategies, including the promotion and protection of breastfeeding and biofortification. The purposes of this introductory paper are to summarize new guidelines on the assessment of population zinc status, as recommended by the World Health Organization (WHO), the United Nations Children's Fund (UNICEF), the International Atomic Energy Agency (IAEA), and IZiNCG, and to provide an overview on several new advances in zinc metabolism. The following papers will then review the intervention strategies individually.