The effect of iron therapy on the growth of iron-replete and iron-deplete children

Iron overload disorders: Growth and gonadal dysfunction in childhood and adolescence

Hemochromatosis (HC) is characterized by the progressive accumulation of iron in the body, resulting in organ damage. Endocrine complications are particularly common, especially when the condition manifests in childhood or adolescence, when HC can adversely affect linear growth or pubertal development, with significant repercussions on quality of life even into adulthood. Therefore, a timely and accurate diagnosis of these disorders is mandatory, but sometimes complex for hematologists without endocrinological support. This is a narrative review focused on puberty and growth disorders during infancy and adolescence aiming to offer guidance for diagnosis, treatment, and proper follow-up. Additionally, it aims to highlight gaps in the existing literature and emphasizes the importance of collaboration among specialists, which is essential in the era of precision medicine.

Scientific opinion on the tolerable upper intake level for iron

Following a request from the European Commission, the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) was asked to deliver a scientific opinion on the tolerable upper intake level (UL) for iron. Systematic reviews were conducted to identify evidence regarding high iron intakes and risk of chronic diseases, adverse gastrointestinal effects and adverse effects of iron supplementation in infancy, young childhood and pregnancy. It is established that systemic iron overload leads to organ toxicity, but no UL could be established. The only indicator for which a dose-response could be established was black stools, which reflect the presence of large amounts of unabsorbed iron in the gut. This is a conservative endpoint among the chain of events that may lead to systemic iron overload but is not adverse per se. Based on interventions in which black stools did not occur at supplemental iron intakes of 20-25 mg/day (added to a background intake of 15 mg/day), a safe level of intake for iron of 40 mg/day for adults (including pregnant and lactating women) was established. Using allometric scaling (body weight0.75), this value was scaled down to children and adolescents and safe levels of intakes between 10 mg/day (1-3 years) and 35 mg/day (15-17 years) were derived. For infants 7-11 months of age who have a higher iron requirement than young children, allometric scaling was applied to the supplemental iron intakes (i.e. 25 mg/day) and resulted in a safe level of supplemental iron intake of 5 mg/day. This value was extended to 4-6 month-old infants and refers to iron intakes from fortified foods and food supplements, not from infant and follow-on formulae. The application of the safe level of intake is more limited than a UL because the intake level at which the risk of adverse effects starts to increase is not defined.

Association Between Heavy Metals Exposure and Height in Chinese Preschoolers

OBJECTIVES

This study aimed to explore the association between multiple metals' exposure and children's height.

METHODS

We collected urine samples and physical measurement data of 1477 preschoolers in China. Children's actual height was measured, and whether reached target height was also assessed. Logistic regression analysis was performed to explore the association between heavy metals and height. The least absolute shrinkage and selection operator regression was used to select the urinary metals, which were highly correlated.

RESULTS

In the single-metal model after adjusting for potential confounders, urinary iron, aluminum, nickel, chrome, titanium, vanadium, selenium, rubidium, and thallium levels were negatively associated with actual height. Urinary iron, aluminum, nickel, and chrome concentrations were also negatively associated with target height.

CONCLUSIONS

The findings suggested that some urinary metal exposure might be associated with height in preschoolers.

Trace Element Interactions, Inflammatory Signaling, and Male Sex Implicated in Reduced Growth Following Excess Oral Iron Supplementation in Pre-Weanling Rats

Iron supplements are frequently provided to infants in high-income countries despite low incidence of iron deficiency. There is growing concern regarding adverse health and development outcomes of excess iron provision in early life. Excess iron may directly damage developing organs through the formation of reactive oxygen species, alter systemic inflammatory signaling, and/or dysregulate trace mineral metabolism. To better characterize the in vivo effects of excess iron on development, we utilized a pre-weanling rat pup model. Lewis rat litters were culled to eight pups (four males and four females) and randomly assigned to daily supplementation groups receiving either vehicle control (CON; 10% w/v sucrose solution) or ferrous sulfate (FS) iron at one of the following doses: 10, 30, or 90 mg iron/kg body weight—FS-10, FS-30, and FS-90, respectively—from postnatal day (PD) 2 through 9. FS-90 litters, but not FS-30 or FS-10, failed to thrive compared to CON litters and had smaller brains on PD 10. Among the groups, FS-90 liver iron levels were highest, as were white blood cell counts. Compared to CON, circulating MCP-1 and liver zinc were increased in FS-90 pups, whereas liver copper was decreased. Growth defects due to excess FS provision in pre-weanling rats may be related to liver injury, inflammation, and altered trace mineral metabolism.

Child linear growth trajectories during the first three years of life in relation to infant iron status: a prospective cohort study in rural Vietnam

Background

Early childhood growth patterns have long-term consequences for health and disease. Little is known about the interplay between growth and iron status during childhood. We explored the interplay between linear growth and iron status during early childhood, by assessing child growth trajectories between 6 and 36 months (m) of age in relation to infant iron status at 6 months of age.

Methods

A cohort study of infants born to women who had previously participated in a cluster randomized controlled trial of antenatal micronutrient supplementation, conducted in rural Vietnam. The relationship between child linear growth trajectories and infant iron status (ferritin concentration) was examined using latent growth curve modeling. Primary outcomes were height for age z scores (HAZ) and growth trajectory between 6 and 36 m of age.

Results

A total of 1112 infants were included in the study. Mean [SD] HAZ scores decreased over time from –0·58 [0·94] at 6 m, to –0·97 [0·99] at 18 m, to –1·14 [0·89] at 36 m of age. There was a steep linear decline in the HAZ scores between 6 and 18 m of age, followed by a slower linear decline from 18 to 36 m of age. Ferritin concentration at 6 m of age was inversely associated with HAZ score at 6 m of age (-0·145, 95% CI [-0.189, -0.101]). There was no association between infant ferritin at 6 m of age and child growth trajectory between 6 and 36 m of age.

Conclusions

Iron status at six months of age did not influence a child’s later linear growth trajectory in this cohort of rural Vietnamese children. Longitudinal studies with repeated ferritin and height measurements are required to better delineate this relationship and inform public health interventions.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40795-022-00505-y.

Gut Microbiome Alterations following Postnatal Iron Supplementation Depend on Iron Form and Persist into Adulthood

The gut microbiota is implicated in the adverse developmental outcomes of postnatal iron supplementation. To generate hypotheses on how changes to the gut microbiota by iron adversely affect development, and to determine whether the form of iron influences microbiota outcomes, we characterized gut microbiome and metabolome changes in Sprague-Dawley rat pups given oral supplements of ferrous sulfate (FS), ferrous bis-glycinate chelate (FC), or vehicle control (CON) on postnatal day (PD) 2−14. Iron supplementation reduced microbiome alpha-diversity (p < 0.0001) and altered short-chain fatty acids (SCFAs) and trimethylamine (TMA) in a form-dependent manner. To investigate the long-term effects of iron provision in early life, an additional cohort was supplemented with FS, FC, or CON until PD 21 and then weaned onto standard chow. At ~8 weeks of age, young adult (YA) rats that received FS exhibited more diverse microbiomes compared to CON (p < 0.05), whereas FC microbiomes were less diverse (p < 0.05). Iron provision resulted in 10,000-fold reduced abundance of Lactobacilli in pre-weanling and YA animals provided iron in early life (p < 0.0001). Our results suggest that in pre-weanling rats, supplemental iron form can generate differential effects on the gut microbiota and microbial metabolism that persist into adulthood.

A novel ferritin L (FerL) in hybrid crucian carp could participate in host defense against Aeromonas hydrophila infection and diminish inflammatory signals

FerL, a multifunctional iron-storage polypeptide, not only exhibited a regulatory role in iron metabolism, but also participated in the regulation of fish immunity. In this study, ORF sequence of WR-FerL was 522 bp, encoding 173 amino acid residues. Tissue-specific analysis revealed that the highest expression of WR-FerL was detected in spleen. A. hydrophila challenge and LPS stimulation could sharply enhance WR-FerL mRNA expression in tissues and fish cells, respectively. Purified WR-FerL fusion peptide exhibited in vitro binding activity to A. hydrophila and endotoxin, limited bacterial dissemination to tissues as well as attenuated A. hydrophila-induced production of pro-inflammatory cytokines. Moreover, WR-FerL overexpression could abrogate NF-κB and TNFα promoter activity in fish cells. These results indicated that WR-FerL could play an important role in host defense against A. hydrophila infection.

Complementary Feeding and Iron Status: "The Unbearable Lightness of Being" Infants

The complementary feeding (CF) period that takes place between 6 and 24 months of age is of key importance for nutritional and developmental reasons during the transition from exclusively feeding on milk to family meals. In 2021, a multidisciplinary panel of experts from four Italian scientific pediatric societies elaborated a consensus document on CF, focusing in particular on healthy term infants. The aim was to provide healthcare providers with useful guidelines for clinical practice. Complementary feeding is also the time window when iron deficiency (ID) and iron deficiency anemia (IDA) are most prevalent. Thus, it is appropriate to address the problem of iron deficiency through nutritional interventions. Adequate iron intake during the first two years is critical since rapid growth in that period increases iron requirements per kilogram more than at any other developmental stage. Complementary foods should be introduced at around six months of age, taking into account infant iron status.

Plant-Based Dietary Practices and Socioeconomic Factors That Influence Anemia in India

While rates of malnutrition have declined over the last decade in India due to successful government interventions, the prevalence of anemia remains high. Staple foods provide almost 70% of the daily iron intake. As staple foods are a rich source of phytate, this ingested iron is poorly absorbed. Currently, 59% of children below 3 years of age, 50% of expectant mothers and 53% of women aged 15-19 years are anemic. The most common intervention strategy has been through the use of iron supplements. While the compliance has been low and supplies irregular, such high rates of anemia cannot be explained by iron deficiency alone. This review attempts to fit dietary and cooking practices, field-level diagnostics, cultural beliefs and constraints in implementation of management strategies into a larger picture scenario to offer insights as to why anemia continues to plague India. Since the rural Indian diet is predominantly vegetarian, we also review dietary factors that influence non-heme iron absorption. As a reference point, we also contrast anemia-related trends in India to the U.S.A. Thus, this review is an effort to convey a holistic evaluation while providing approaches to address this public health crisis.

The critical roles of iron during the journey from fetus to adolescent: Developmental aspects of iron homeostasis

Iron is indispensable for human life. However, it is also potentially toxic, since it catalyzes the formation of harmful oxidative radicals in unbound form and may facilitate pathogen growth. Therefore, iron homeostasis needs to be tightly regulated. Rapid growth and development require large amounts of iron, while (especially young) children are vulnerable to infections with iron-dependent pathogens due to an immature immune system. Moreover, unbalanced iron status early in life may have effects on the nervous system, immune system and gut microbiota that persist into adulthood. In this narrative review, we assess the critical roles of iron for growth and development and elaborate how the body adapts to physiologically high iron demands during the journey from fetus to adolescent. As a first step towards the development of clinical guidelines for the management of iron disorders in children, we summarize the unmet needs regarding the developmental aspects of iron homeostasis.

Postnatal Iron Supplementation with Ferrous Sulfate vs. Ferrous Bis-Glycinate Chelate: Effects on Iron Metabolism, Growth, and Central Nervous System Development in Sprague Dawley Rat Pups

Iron-fortified formulas and iron drops (both usually ferrous sulfate, FS) prevent early life iron deficiency, but may delay growth and adversely affect neurodevelopment by providing excess iron. We used a rat pup model to investigate iron status, growth, and development outcomes following daily iron supplementation (10 mg iron/kg body weight, representative of iron-fortified formula levels) with FS or an alternative, bioavailable form of iron, ferrous bis-glycinate chelate (FC). On postnatal day (PD) 2, sex-matched rat litters (n = 3 litters, 10 pups each) were randomly assigned to receive FS, FC, or vehicle control until PD 14. On PD 15, we evaluated systemic iron regulation and CNS mineral interactions and we interrogated iron loading outcomes in the hippocampus, in search of mechanisms by which iron may influence neurodevelopment. Body iron stores were elevated substantially in iron-supplemented pups. All pups gained weight normally, but brain size on PD 15 was dependent on iron source. This may have been associated with reduced hippocampal oxidative stress but was not associated with CNS mineral interactions, iron regulation, or myelination, as these were unchanged with iron supplementation. Additional studies are warranted to investigate iron form effects on neurodevelopment so that iron recommendations can be optimized for all infants.

Chimeric ferritin H in hybrid crucian carp exhibits a similar down-regulation in lipopolysaccharide-induced NF-κB inflammatory signal in comparison with Carassius cuvieri and Carassius auratus red var

Ferritin H can participate in the regulation of teleostean immunity. ORF sequences of RCC/WCC/WR-ferritin H were 609 bp, while WR-ferritin H gene possessed chimeric fragments or offspring-specific mutations. In order to elucidate regulation of immune-related signal transduction, three fibroblast-like cell lines derived from caudal fin of red crucian carp (RCC), white crucian carp (WCC) and their hybrid offspring (WR) were characterized and designated as RCCFCs, WCCFCs and WRFCs. A sharp increase of ferritin H mRNA was observed in RCCFCs, WCCFCs and WRFCs following lipopolysaccharide (LPS) challenge. Overexpression of RCC/WCC/WR-ferritin H can decrease MyD88-IRAK4 signal and antagonize NF-κB, TNFα promoter activity in RCCFCs, WCCFCs and WRFCs, respectively. These results indicated that ferritin H in hybrid offspring harbors highly-conserved domains with a close sequence similarity to those of its parents, playing a regulatory role in inflammatory signals.

Iron Deficiency and Iron Excess Differently Affect Dendritic Architecture of Pyramidal Neurons in the Hippocampus of Piglets

BACKGROUND

Both iron deficiency and overload may adversely affect neurodevelopment.

OBJECTIVES

The study assessed how changes in early-life iron status affect iron homeostasis and cytoarchitecture of hippocampal neurons in a piglet model.

METHODS

On postnatal day (PD) 1, 30 Hampshire × Yorkshire crossbreed piglets (n = 15/sex) were stratified by sex and litter and randomly assigned to experimental groups receiving low (L-Fe), adequate (A-Fe), or high (H-Fe) levels of iron supplement during the pre- (PD1-21) and postweaning periods (PD22-35). Pigs in the L-Fe, A-Fe, and H-Fe groups orally received 0, 1, and 30 mg Fe · kg weight-1 · d-1 preweaning and were fed a diet containing 30, 125, and 1000 mg Fe/kg postweaning, respectively. Heme indexes were analyzed weekly, and gene and protein expressions of iron regulatory proteins in duodenal mucosa, liver, and hippocampus were analyzed through qRT-PCR and western blot, respectively, on PD35. Hippocampal neurons stained using the Golgi-Cox method were traced and their dendritic arbors reconstructed in 3-D using Neurolucida. Dendritic complexity was quantified using Sholl and branch order analyses.

RESULTS

Pigs in the L-Fe group developed iron deficiency anemia (hemoglobin = 8.2 g/dL, hematocrit = 20.1%) on PD35 and became stunted during week 5 with lower final body weight than H-Fe group pigs (6.6 compared with 9.6 kg, P < 0.05). In comparison with A-Fe, H-Fe increased hippocampal ferritin expression by 38% and L-Fe decreased its expression by 52% (P < 0.05), suggesting altered hippocampal iron stores. Pigs in the H-Fe group had greater dendritic complexity in CA1/3 pyramidal neurons than L-Fe group pigs as shown by more dendritic intersections with Sholl rings (P ≤ 0.04) and a greater number of dendrites (P ≤ 0.016).

CONCLUSIONS

In piglets, the developing hippocampus is susceptible to perturbations by dietary iron, with deficiency and overload differentially affecting dendritic arborization.

Iron status and inherited haemoglobin disorders modify the effects of micronutrient powders on linear growth and morbidity among young Lao children in a double-blind randomised trial

Some studies found that providing micronutrient powder (MNP) causes adverse health outcomes, but modifying factors are unknown. We aimed to investigate whether Fe status and inherited Hb disorders (IHbD) modify the impact of MNP on growth and diarrhoea among young Lao children. In a double-blind controlled trial, 1704 children of age 6–23 months were randomised to daily MNP (with 6 mg Fe plus fourteen micronutrients) or placebo for about 36 weeks. IHbD, and baseline and final Hb, Fe status and anthropometrics were assessed. Caregivers provided weekly morbidity reports. At enrolment, 55·6 % were anaemic; only 39·3 % had no sign of clinically significant IHbD. MNP had no overall impact on growth and longitudinal diarrhoea prevalence. Baseline Hb modified the effect of MNP on length-for-age (LAZ) (P for interaction = 0·082). Among children who were initially non-anaemic, the final mean LAZ in the MNP group was slightly lower (–1·93 (95 % CI –1·88, –1·97)) v. placebo (–1·88 (95 % CI –1·83, –1·92)), and the opposite occurred among initially anaemic children (final mean LAZ –1·90 (95 % CI –1·86, –1·94) in MNP v. –1·92 (95 % CI –1·88, –1·96) in placebo). IHbD modified the effect on diarrhoea prevalence (P = 0·095). Among children with IHbD, the MNP group had higher diarrhoea prevalence (1·37 (95 % CI 1·17, 1·59) v. 1·21 (95 % CI 1·04, 1·41)), while it was lower among children without IHbD who received MNP (1·15 (95 % CI 0·95, 1·39) v. 1·37 (95 % CI 1·13, 1·64)). In conclusion, there was a small adverse effect of MNP on growth among non-anaemic children and on diarrhoea prevalence among children with IHbD.

Excess Iron Enhances Purine Catabolism Through Activation of Xanthine Oxidase and Impairs Myelination in the Hippocampus of Nursing Piglets

BACKGROUND

Few studies have addressed the risk of nutritional iron overexposure in infancy. We previously found that excess dietary iron in nursing piglets resulted in iron overload in the liver and hippocampus and diminished socialization with novel conspecifics in a test for social novelty preference.

OBJECTIVES

This experiment aimed to identify metabolites and metabolic pathways affected by iron overload in the liver and hippocampus of nursing piglets.

METHODS

Liver and hippocampal tissues collected from 22-d-old piglets (Hampshire × Yorkshire crossbreed; 5.28 ± 0.53 kg body weight; 50% male) that received orally 0 (NI group) or 50 mg iron/(d · kg body weight) (HI group) from postnatal day (PD) 2 to PD21 were analyzed for mRNA and protein expression and enzyme activity of xanthine oxidase (XO). Untargeted metabolomics was performed using GC-MS. Expression of myelin basic protein (MBP) in the hippocampus was determined using western blot.

RESULTS

There were 108 and 126 metabolites identified in the hippocampus and liver, respectively. Compared with NI, HI altered 15 metabolites (P < 0.05, q < 0.2) in the hippocampus, including a reduction in myo-inositol (0.86-fold) and N-acetylaspartic acid (0.84-fold), 2 metabolites important for neuronal function and myelination. Seven metabolites involved in purine and pyrimidine metabolism (e.g., hypoxanthine, xanthine, and β-alanine) were coordinately changed in the hippocampus (P < 0.05, q < 0.2), suggesting that iron excess enhanced purine catabolism. The mRNA expression (2.3-fold) (P < 0.05) and activity of XO, a rate-limiting enzyme in purine degradation, was increased. Excess iron increased hippocampal lipid peroxidation by 74% (P < 0.05) and decreased MBP by 44% (P = 0.053). The hepatic metabolome was unaffected.

CONCLUSIONS

In nursing piglets, excess iron enhances hippocampal purine degradation through activation of XO, which may induce oxidative stress and alter energy metabolism in the developing brain.

Iron Deficiency and Iron Homeostasis in Low Birth Weight Preterm Infants: A Systematic Review

Iron is an essential micronutrient that is involved in many functions in humans, as it plays a critical role in the growth and development of the central nervous system, among others. Premature and low birth weight infants have higher iron requirements due to increased postnatal growth compared to that of term infants and are, therefore, susceptible to a higher risk of developing iron deficiency or iron deficiency anemia. Notwithstanding, excess iron could affect organ development during the postnatal period, particularly in premature infants that have an immature and undeveloped antioxidant system. It is important, therefore, to perform a review and analyze the effects of iron status on the growth of premature infants. This is a transversal descriptive study of retrieved reports in the scientific literature by a systematic technique. PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines were adapted for the review strategy. The inclusion criteria for the studies were made using the PICO (population, intervention, comparison, outcome) model. Consequently, the systematic reviews that included studies published between 2008–2018 were evaluated based on the impact of iron status on parameters of growth and development in preterm infants.

The Benefits and Risks of Iron Supplementation in Pregnancy and Childhood

Iron deficiency is the most common micronutrient deficiency in the world and disproportionately affects pregnant women and young children. Iron deficiency has negative effects on pregnancy outcomes in women and on immune function and neurodevelopment in children. Iron supplementation programs have been successful in reducing this health burden. However, iron supplementation of iron-sufficient individuals is likely not necessary and may carry health risks for iron-sufficient and potentially some iron-deficient populations. This review considers the physiology of iron as a nutrient and how this physiology informs decision-making about weighing the benefits and risks of iron supplementation in iron-deficient, iron-sufficient, and iron-overloaded pregnant women and children.

The Importance of Iron Status for Young Children in Low- and Middle-Income Countries: A Narrative Review

Early childhood is characterised by high physiological iron demand to support processes including blood volume expansion, brain development and tissue growth. Iron is also required for other essential functions including the generation of effective immune responses. Adequate iron status is therefore a prerequisite for optimal child development, yet nutritional iron deficiency and inflammation-related iron restriction are widespread amongst young children in low- and middle-income countries (LMICs), meaning iron demands are frequently not met. Consequently, therapeutic iron interventions are commonly recommended. However, iron also influences infection pathogenesis: iron deficiency reduces the risk of malaria, while therapeutic iron may increase susceptibility to malaria, respiratory and gastrointestinal infections, besides reshaping the intestinal microbiome. This means caution should be employed in administering iron interventions to young children in LMIC settings with high infection burdens. In this narrative review, we first examine demand and supply of iron during early childhood, in relation to the molecular understanding of systemic iron control. We then evaluate the importance of iron for distinct aspects of physiology and development, particularly focusing on young LMIC children. We finally discuss the implications and potential for interventions aimed at improving iron status whilst minimising infection-related risks in such settings. Optimal iron intervention strategies will likely need to be individually or setting-specifically adapted according to iron deficiency, inflammation status and infection risk, while maximising iron bioavailability and considering the trade-offs between benefits and risks for different aspects of physiology. The effectiveness of alternative approaches not centred around nutritional iron interventions for children should also be thoroughly evaluated: these include direct targeting of common causes of infection/inflammation, and maternal iron administration during pregnancy.

Integrating themes, evidence gaps, and research needs identified by workshop on iron screening and supplementation in iron-replete pregnant women and young children

This report addresses the evidence and the uncertainties, knowledge gaps, and research needs identified by participants at the NIH workshop related to iron screening and routine iron supplementation of largely iron-replete pregnant women and young children (6-24 mo) in developed countries. The workshop presentations and panel discussions focused on current understanding and knowledge gaps related to iron homeostasis, measurement of and evidence for iron status, and emerging concerns about supplementing iron-replete members of these vulnerable populations. Four integrating themes emerged across workshop presentations and discussion and centered on 1) physiologic or developmental adaptations of iron homeostasis to pregnancy and early infancy, respectively, and their implications, 2) improvement of the assessment of iron status across the full continuum from iron deficiency anemia to iron deficiency to iron replete to iron excess, 3) the linkage of iron status with health outcomes beyond hematologic outcomes, and 4) the balance of benefit and harm of iron supplementation of iron-replete pregnant women and young children. Research that addresses these themes in the context of the full continuum of iron status is needed to inform approaches to the balancing of benefits and harms of screening and routine supplementation.

Excess iron intake as a factor in growth, infections, and development of infants and young children

The provision of iron via supplementation or the fortification of foods has been shown to be effective in preventing and treating iron deficiency and iron deficiency anemia in infants and young children. However, iron is a pro-oxidative element and can have negative effects on biological systems even at moderate amounts. An increasing number of studies have reported adverse effects of iron that was given to infants and young-children populations who initially were iron replete. These effects include decreased growth (both linear growth and weight), increased illness (usually diarrhea), interactions with other trace elements such as copper and zinc, altered gut microbiota to more pathogenic bacteria, increased inflammatory markers, and impaired cognitive and motor development. If these results can be confirmed by larger and well-controlled studies, it may have considerable programmatic implications (e.g., the necessity to screen for iron status before interventions to exclude iron-replete individuals). A lack of understanding of the mechanisms underlying these adverse outcomes limits our ability to modify present supplementation and fortification strategies. This review summarizes studies on the adverse effects of iron on various outcomes; suggests possible mechanisms that may explain these observations, which are usually made in clinical studies and intervention trials; and gives examples from animal models and in vitro studies. With a better understanding of these mechanisms, it may be possible to find novel ways of providing iron in a form that causes fewer or no adverse effects even when subjects are iron replete. However, it is apparent that our understanding is limited, and research in this area is urgently needed.

Iron status of young children in Europe

Iron deficiency (ID) is common in young children aged 6-36 mo. Although the hazards associated with iron deficiency anemia (IDA) are well known, concerns about risks associated with excess iron intake in young children are emerging. To characterize iron status in Europe, we describe the prevalence of ID, IDA, iron repletion, and excess stores with the use of published data from a systematic review on iron intake and deficiency rates, combined with other selected iron status data in young European children. Various definitions for ID and IDA were applied across studies. ID prevalence varied depending on socioeconomic status and type of milk fed (i.e., human or cow milk or formula). Without regard to these factors, ID was reported in 3-48% of children aged ≥12 mo across the countries. For 6- to 12-mo-old infants, based on studies that did not differentiate these factors, ID prevalence was 4-18%. IDA was <5% in most studies in Northern and Western Europe but was considerably higher in Eastern Europe (9-50%). According to current iron status data from a sample of healthy Western European children aged 12-36 mo, 69% were iron replete, and the 97.5th percentile for serum ferritin (SF) was 64.3 μg/L. In another sample, 79% of 24-mo-old children were iron replete, and the 97.5th percentile for SF was 57.3 μg/L. Average iron intake in most countries studied was close to or below the UK's Recommended Dietary Allowance. In conclusion, even in healthy European children aged 6-36 mo, ID is still common. In Western European populations for whom data were available, approximately three-quarters of children were found to be iron replete, and excess iron stores (SF >100 μg/L) did not appear to be a concern. Consensus on the definitions of iron repletion and excess stores, as well as on ID and IDA, is needed.

Introduction to workshop on iron screening and supplementation in iron-replete pregnant women and young children

The NIH Office of Dietary Supplements convened a public workshop on iron screening and supplementation in iron-replete pregnant women and young children in 2016 in Bethesda, Maryland. The starting point for the workshop was the recent reports from the US Preventive Services Task Force concluding that there was insufficient evidence to evaluate the benefits and harms associated with iron screening and routine supplementation among asymptomatic pregnant women and young children (6-24 mo old) in the United States. The goal of the workshop was to explore and refine understanding about the existing knowledge gaps and research needs associated with these preventive services for these groups. Given the focus on the United States, planning for the workshop took into account the higher iron status in the United States compared with developing countries and, in turn, included a focus on iron-replete individuals consistent with the U-shaped risk curve for nutrient-health relations. Topic areas included adaptations in iron homeostasis associated with pregnancy and young childhood, the impact of inflammation, measurement of iron status, current estimates of iron status for pregnant women and young children in the United States and in Europe, and emerging evidence suggesting adverse effects associated with iron supplementation of iron-replete individuals. A crosscutting dialogue conducted at the close of the workshop formed the basis for a workshop summary that specified evidence gaps and research needs in a range of areas centered on the relation of these adaptations of iron homeostasis with the response to and risk from iron supplementation as well as the need for indicators informative of the full continuum of iron status and based on health outcomes, not just erythropoiesis.

Effects of iron supplementation on growth, gut microbiota, metabolomics and cognitive development of rat pups

BACKGROUND

Iron deficiency is common during infancy and therefore iron supplementation is recommended. Recent reports suggest that iron supplementation in already iron replete infants may adversely affect growth, cognitive development, and morbidity.

METHODS

Normal and growth restricted rat pups were given iron daily (30 or 150 μg/d) from birth to postnatal day (PD) 20, and followed to PD56. At PD20, hematology, tissue iron, and the hepatic metabolome were measured. The plasma metabolome and colonic microbial ecology were assessed at PD20 and PD56. T-maze (PD35) and passive avoidance (PD40) tests were used to evaluate cognitive development.

RESULTS

Iron supplementation increased iron status in a dose-dependent manner in both groups, but no significant effect of iron on growth was observed. Passive avoidance was significantly lower only in normal rats given high iron compared with controls. In plasma and liver of normal and growth-restricted rats, excess iron increased 3-hydroxybutyrate and decreased several amino acids, urea and myo-inositol. While a profound difference in gut microbiota of normal and growth-restricted rats was observed, with iron supplementation differences in the abundance of strict anaerobes were observed.

CONCLUSION

Excess iron adversely affects cognitive development, which may be a consequence of altered metabolism and/or shifts in gut microbiota.

Simulated effects of home fortification of complementary foods with micronutrient powders on risk of inadequate and excessive intakes in West Gojjam, Ethiopia

Home fortification of complementary foods (CFs) with multiple micronutrient powders (MNPs) is being scaled up in various countries, but little is known about the prevailing complementary feeding practices and the type and nutrient gaps to be filled with MNPs. The present study evaluated the complementary feeding practices of young children and simulated the risk of inadequate and excessive intakes associated with home fortification with MNPs. We have assessed the sociodemographic status, anthropometry, and complementary feeding practices of young children (N = 122) in Mecha district, rural Ethiopia. Using a 2-day, quantitative 24-hr recall, usual intakes of energy, protein, iron, zinc, and calcium were estimated. The risks of inadequate and excessive iron and zinc intakes with or without home fortification scenarios were assessed. The simulations considered intakes from CFs assuming average breast milk contributions and additional nutrients provided by the MNPs. Stunting was highly prevalent (50%) and was associated with a lower dietary diversity (P = .009) and nutrient intakes from the CFs. Median energy, zinc, and calcium intakes were below the estimated needs from CFs; protein needs were met. Median dietary iron intake appeared adequate, but 76%, 95% CI [68%, 84%], of children had inadequate intake (assuming low bioavailability), whereas another 8%, 95% CI: [3%, 13%], had excessive intakes. Simulation of daily and alternative day's fortification with MNP decreased the prevalence of inadequate iron and zinc intake but significantly increased the risk of excessive intakes that remained unacceptably high for iron (>2.5%). Untargeted MNP interventions may lead to excessive intakes, even in settings where poor complementary feeding practices are prevalent.

Iron Stores in Term and Late Preterm Small for Gestational Age and Appropriate for Gestational Age Neonates at Birth and in Early Infancy

OBJECTIVE

To compare body iron stores in late preterm and term small for gestational age (SGA) infants with gestation matched appropriate-for-gestational age (AGA) infants at birth and at 2 mo of age.

METHODS

In this prospective observational study, live births of 34-42 wk gestation and SGA (<10th centile for GA) were enrolled along with gestation matched AGA (10th-90th centile for GA) infants. Infants' blood samples were taken within 2 h of delivery, and repeated at 60 ± 7 d of life. Primary outcome was serum ferritin at birth and 60 d of age. Secondary outcomes were hematocrit at birth and 60 d and need for transfusion until 60 d of life.

RESULTS

A total of 37 SGA (gestation 37.2 ± 1.9 wk, birth weight 1861 ± 401 g) and 30 AGA infants (gestation 37.3 ± 1.9 wk, birth weight 2607 ± 405 g) were enrolled in the study. There was no difference in the serum ferritin between AGA and SGA infants at birth {median [IQR]: 254.0 [214.3-293.8] vs. 259.7 [217.8-301.5] μg/L; p = 0.85} or 60 d of life {147.2 [101.4-193.0] vs. 155.0 [106.6-203.6] μg/L; p = 0.81}. Mean hematocrit was 55.5 ± 9.6 vs. 52.4 ± 5.0 at birth (p = 0.10) and 32.1 ± 4.9 vs. 31.6 ± 3.8 at 60 d (p = 0.77) in SGA and AGA infants respectively. No infant required blood transfusion during the study period.

CONCLUSIONS

Iron stores of late preterm and term SGA infants are comparable to term AGA infants at birth and 2 mo of age. Recommendations on iron supplementation to these infants need to be formulated through appropriately designed randomized trials.

Ethiopian pre-school children consuming a predominantly unrefined plant-based diet have low prevalence of iron-deficiency anaemia

Objective

Children from low-income countries consuming predominantly plant-based diets but little animal products are considered to be at risk of Fe deficiency. The present study determined the Fe status of children from resource-limited rural households.

Design

A cross-sectional study.

Setting

Twenty six kebeles (the smallest administrative unit) from six zones of the Amhara region, Ethiopia.

Subjects

Children aged 54–60 months (n 628).

Results

Grain, roots or tubers were the main dietary components consumed by 100 % of the study participants, followed by pulses, legumes or nuts (66·6 %). Consumption of fruit and vegetables (19·3 %) and meat, poultry and fish (2·2 %) was low. Children had a mean dietary diversity score of 2·1 (sd 0·8). Most children (74·8 %, n 470) were in the lowest dietary diversity group (1–2 food groups). Rate of any morbidity in the preceding 14 d was 22·9 % (n 114). Infection or inflammation (α1-acid glycoprotein >1·2 g/l) was present in 30·2 % (n 184) of children. Children had a high rate of stunting (43·2 %). Of the total sample, 13·6 % (n 82) of children were anaemic, 9·1 % (n 57) were Fe deficient and 5·3 % (n 32) had Fe-deficiency anaemia. Fe-deficiency erythropoiesis was present in 14·2 % (n 60) of children.

Conclusions

Despite consuming a predominantly plant-based diet and little animal-source foods, there was a low prevalence of Fe-deficiency anaemia. This illustrates that dietary patterns can be inharmonious with Fe biochemical status; thus, Fe-related interventions require biochemical screening.

An Opinion on "Staging" of Infant Formula: A Developmental Perspective on Infant Feeding

Breast milk is a dynamic fluid with compositional changes occurring throughout the period of lactation. Some of these changes in nutrient concentrations reflect the successively slowing growth rate and developmental changes in metabolic requirements that infants undergo during the first year of life. Infant formula, in contrast, has a static composition, intended to meet the nutritional requirements of infants from birth to 6 or 12 months of age. To better fit the metabolic needs of infants and to avoid nutrient limitations or excesses, we suggest that infant formulas should change in composition with the age of the infant, that is, different formulas are created/used for different ages during the first year of life. We propose that specific formulas for 0 to 3 months (stage 1), 3 to 6 months (stage 2), and 6 to 12 months (stage 3) of age may be nutritionally and physiologically advantageous to infants. Although this initially may impose some difficult practical/conceptual issues, we believe that this staging concept would improve nutrition of formula-fed infants and, ultimately, improve outcomes and make their performance more similar to that of breast-fed infants.

Screening and routine supplementation for iron deficiency anemia: a systematic review

BACKGROUND AND OBJECTIVES

Supplementation and screening for iron-deficiency anemia (IDA) in young children may improve growth and development outcomes. The goal of this study was to review the evidence regarding the benefits and harms of screening and routine supplementation for IDA for the US Preventive Services Task Force.

METHODS

We searched Medline and Cochrane databases (1996-August 2014), as well as reference lists of relevant systematic reviews. We included trials and controlled observational studies regarding the effectiveness and harms of routine iron supplementation and screening in children ages 6 to 24 months conducted in developed countries. One author extracted data, which were checked for accuracy by a second author. Dual quality assessment was performed.

RESULTS

No studies of iron supplementation in young children reported on the diagnosis of neurodevelopmental delay. Five of 6 trials sparsely reporting various growth outcomes found no clear benefit of supplementation. After 3 to 12 months, Bayley Scales of Infant Development scores were not significantly different in 2 trials. Ten trials assessing iron supplementation in children reported inconsistent findings for hematologic measures. Evidence regarding the harms of supplementation was limited but did not indicate significant differences. No studies assessed the benefits or harms of screening or the association between improvement in impaired iron status and clinical outcomes. Studies may have been underpowered, and control factors varied and could have confounded results.

CONCLUSIONS

Although some evidence on supplementation for IDA in young children indicates improvements in hematologic values, evidence on clinical outcomes is lacking. No randomized controlled screening studies are available.

Iron supplementation until 6 months protects marginally low-birth-weight infants from iron deficiency during their first year of life

OBJECTIVES

Low-birth-weight (LBW) infants (<2500 g) have an increased risk of iron deficiency (ID) during their first 6 months of life. The optimal dose and duration of iron supplementation to LBW infants are, however, unknown. The objective of the present study was to investigate the long-term effect on iron status and growth in marginally LBW (2000-2500 g) infants, of iron supplements given until 6 months of life.

METHODS

In a randomized controlled trial, 285 healthy marginally LBW infants received 0, 1, or 2 mg · kg(-1) · day(-1) of iron supplements from 6 weeks to 6 months of age. At 12 months and 3.5 years of life we measured length, weight, head circumference, and indicators of iron status (hemoglobin, ferritin, mean corpuscular volume, and transferrin saturation) and assessed the prevalence of iron depletion, functional ID, and ID anemia.

RESULTS

At 12 months of age, there was a significant difference in ferritin between the groups (P = 0.006). Furthermore, there was a significant difference in the prevalence of iron depletion (23.7%, 10.6%, and 6.8%, respectively, in the placebo, 1-mg, and 2-mg groups, P = 0.009) and similar nonsignificant trends for functional ID and ID anemia. At 3.5 years of life there were no significant differences in iron status and the mean prevalence of iron depletion was 3.2%. Anthropometric data were not affected by the intervention.

CONCLUSIONS

Iron supplements with 2 mg · kg(-1) · day(-1) until 6 months of life effectively reduces the risk of ID during the first 12 months of life and is an effective intervention for preventing early ID in marginally LBW infants.

The effect of folic acid supplementation with ferrous sulfate on the linear and ponderal growth of children aged 6-24 months: a randomized controlled trial

BACKGROUND/OBJECTIVES

Studies evaluating the effect of folic acid supplementation, either alone or in combination with iron, on the linear and ponderal growth of children are practically nonexistent. The aim of this study was to assess the effect of folic acid supplementation with ferrous sulfate on both linear growth and weight gain in anemic and nonanemic children attending Municipal Daycare Centers in Goiania, State of Goias, Brazil.

SUBJECTS/METHODS

A double-blind, randomized, controlled trial was conducted on 188 children aged 6-24 months. The effects of ferrous sulfate and folic acid supplementation were evaluated using the analysis of variance procedure, based on a double factorial model with two factors of fixed effects (folic acid supplementation and ferrous sulfate supplementation), adjusted for initial weight. The level of significance was 0.05.

RESULTS

The children who received folic acid supplementation showed greater weight gain than the monthly average weight gain of those not given the supplement (P=0.026). This effect was independent of the dose of ferrous sulfate (P for interaction=0.693). Folic acid supplementation increased the gain of weight-for-age Z-score when compared with the placebo group (P=0.018), independent of the dose of ferrous sulfate.

CONCLUSION

Folic acid had no effect on linear growth. The use of folic acid supplementation increased the monthly average weight gain and the gain in weight-for-age Z-score compared with the placebo group. This effect was independent of the dose of ferrous sulfate.

Adverse effect after cessation of rats' unjustified iron or iron and zinc supplementation on hematological parameters but not ferritin concentration

BACKGROUND & AIMS

Studies on the impact of supplementation cessation are lacking. We investigated the effect of iron and iron/zinc supplementation and cessation of this intervention on iron status parameters.

METHODS

The study was conducted on 6-week male Wistar rats, in 3 stages: 4-week adaptation to the diets: C--control (AIN-93M) and D--iron deficient (mineral mix without iron); 4-week supplementation: 10-times more iron (CSFe, DSFe) or iron/zinc (CSFeZn, DSFeZn) compared to C; 2-week post-supplementation period (the same diets as in the first stage). Red blood cell count, hemoglobin, hematocrit, transferrin saturation (TSAT) and ferritin concentration were determined.

RESULTS

After stage II D rats had statistically significantly (p-value ≤ 0.05) lower hemoglobin and TSAT in comparison to DSFe rats, but not DSFeZn, and significantly lower ferritin concentration in comparison to DSFe and DSFeZn rats. After stage III, CSFe and CSFeZn rats had a significantly lower level of all analyzed hematology parameters compared to C, in contrast rats fed DSFe and DSFeZn diets had higher hemoglobin concentration and hematocrit in comparison to D group. Moreover, in comparison to D rats those fed DSFe diet had higher TSAT and those fed DSFe and DSFeZn diets had significantly higher ferritin concentration.

CONCLUSIONS

After cessation of unjustified both iron and iron/zinc supplementation resulted in an adverse effect on hematological but not other iron status parameters. In the situation of iron deficiency in the diet, iron supplementation alone had a prolonged beneficial effect and was more effective than simultaneous iron/zinc supplementation in the improvement of the iron status.

Iron requirements of infants and toddlers

Iron deficiency (ID) is the most common micronutrient deficiency worldwide and young children are a special risk group because their rapid growth leads to high iron requirements. Risk factors associated with a higher prevalence of ID anemia (IDA) include low birth weight, high cow's-milk intake, low intake of iron-rich complementary foods, low socioeconomic status, and immigrant status. The aim of this position paper was to review the field and provide recommendations regarding iron requirements in infants and toddlers, including those of moderately or marginally low birth weight. There is no evidence that iron supplementation of pregnant women improves iron status in their offspring in a European setting. Delayed cord clamping reduces the risk of ID. There is insufficient evidence to support general iron supplementation of healthy European infants and toddlers of normal birth weight. Formula-fed infants up to 6 months of age should receive iron-fortified infant formula, with an iron content of 4 to 8 mg/L (0.6-1.2 mg(-1) · kg(-1) · day(-1)). Marginally low-birth-weight infants (2000-2500 g) should receive iron supplements of 1-2 mg(-1) · kg(-1) · day(-1). Follow-on formulas should be iron-fortified; however, there is not enough evidence to determine the optimal iron concentration in follow-on formula. From the age of 6 months, all infants and toddlers should receive iron-rich (complementary) foods, including meat products and/or iron-fortified foods. Unmodified cow's milk should not be fed as the main milk drink to infants before the age of 12 months and intake should be limited to <500 mL/day in toddlers. It is important to ensure that this dietary advice reaches high-risk groups such as socioeconomically disadvantaged families and immigrant families.

Effect of daily iron supplementation on health in children aged 4-23 months: a systematic review and meta-analysis of randomised controlled trials

BACKGROUND

About 47% of preschool children worldwide are anaemic. Daily oral iron supplementation is a commonly recommended intervention for treatment and prevention of anaemia, but the efficacy and safety of iron supplementation programmes is debated. Thus, we systematically reviewed the evidence for benefit and safety of daily iron supplementation in children aged 4-23 months.

METHODS

We searched Scopus and Medline, from inception to Feb 5, 2013, WHO databases, theses repositories, grey literature, and references. Randomised controlled trials that assigned children 4-23 months of age to daily oral iron supplementation versus control were eligible. We calculated mean difference (MD) or standard MD (SMD) for continuous variables, risk ratios for dichotomous data, and rate ratios for rates. We quantified heterogeneity with the I(2) test and synthesised all data with a random-effects model. This review is registered with the International Prospective Register of Systematic Reviews, number CRD42011001208.

FINDINGS

Of 9533 citations identified by the search strategy, 49 articles from 35 studies were eligible; these trials included 42,306 children. Only nine studies were judged to be at low risk of bias. In children receiving iron supplements, the risk ratio for anaemia was 0·61 (95% CI 0·50-0·74; 17 studies, n=4825), for iron deficiency was 0·30 (0·15-0·60; nine studies, n=2464), and for iron deficiency anaemia was 0·14 (0·10-0·22; six studies, n=2145). We identified no evidence of difference in mental (MD 1·65, 95% CI -0·63 to 3·94; six studies, n=1093) or psychomotor development (1·05, -1·36 to 3·46; six studies, n=1086). We noted no significant differences in final length or length-for-age, or final weight or weight-for-age. Children randomised to iron had slightly lesser length (SMD -0·83, -1·53 to -0·12; eight studies, n=868) and weight gain (-1·12, -1·19 to -0·33) over the course of the studies. Vomiting (risk ratio 1·38, 95% CI 1·10-1·73) and fever (1·16, 1·02-1·31) were more prevalent in children receiving iron.

INTERPRETATION

In children aged 4-23 months, daily iron supplementation effectively reduces anaemia. However, the adverse effect profile of iron supplements and effects on development and growth are uncertain. Adequately powered trials are needed to establish the non-haematological benefits and risks from iron supplementation in this group.

FUNDING

Victoria Fellowship (Government of Victoria, Australia); CRB Blackburn Scholarship (Royal Australasian College of Physicans); Overseas Research Experience Scholarship, University of Melbourne.

An evidence-based systematic review of vitamin A by the natural standard research collaboration

An evidence-based systematic review of vitamin A by the Natural Standard Research Collaboration consolidates the safety and efficacy data available in the scientific literature using a validated and reproducible grading rationale. This paper includes written and statistical analysis of clinical trials, plus a compilation of expert opinion, folkloric precedent, history, pharmacology, kinetics/dynamics, interactions, adverse effects, toxicology, and dosing.

Iron supplementation is positively associated with increased serum ferritin levels in 9-month-old Danish infants

Fe deficiency is still common in infancy, even in affluent societies, and has prompted Fe fortification of food products and use of Fe supplements in many populations. In the present study, we tested the hypothesis that Fe status among 9-month-old infants following the Danish Fe supplementation recommendation (>400 ml Fe-fortified formula or 8 mg Fe/d) is associated with more favourable levels of Fe status indicators compared to those not following the recommendation. A random sample of 9-month-old infants living in Copenhagen was established and 312 healthy term infants were examined at 9·1 (sd0·3) months of age. Blood samples were available from 278 infants. Overall, twenty infants (7·8 %) had Fe deficiency (serum ferritin < 12 μg/l) and < 1 % had Fe deficiency anaemia (serum ferritin < 12 μg/l and Hb < 100 g/l). Serum ferritin was positively associated with birth weight (P < 0·001), intake of fortified formula and follow-on formula (P = 0·001), and female sex (P < 0·001). Cow's milk intake and length of exclusive breast-feeding were negatively associated with Hb levels (P = 0·013 andP < 0·001). Serum ferritin levels were significantly higher (P < 0·0001) and transferrin receptor (TfR) was significantly lower (P = 0·003) among infants (n188) meeting the Fe supplementation recommendation compared to those (n67) not meeting the recommendation. No significant difference between these two groups was found for Hb. In conclusion, this study confirmed that Fe status of infants following the Danish Fe supplementation recommendation was significantly associated with increased serum ferritin and decreased levels of TfR indicating more favourable Fe status, compared to infants not following the recommendation.

Equivalent effects on fecal reactive oxygen species generation with oral supplementation of three iron compounds: ferrous sulfate, sodium iron EDTA and iron polymaltose

BACKGROUND

In any context of iron supplementation in the prenatal prophylaxis or therapeutic dosage range, a large amount will remain unabsorbed and pass through the intestinal tract into the colonic digesta possibly causing increased oxidation.

AIM

To compare the generation of fecal reactive oxygen species (ROS) in situ after daily consumption of 100 mg of elemental iron in three frequently used forms of iron supplements.

METHODS

Ten healthy, iron-repleted adult males were investigated before and during supplementation with three oral iron compounds: 100 mg of oral iron were given as ferrous sulfate, Na Fe-EDTA and iron polymaltose for 6 days to each subject in an individually stratified sequence. Stool samples were collected and analyzed for iron content and the in situ generation of fecal ROS.

RESULTS

Significant increases in fecal ROS generation were observed during oral iron supplementation. No statistical differences were seen in either residual concentrations of non-heme iron in stool or the level of fecal ROS generation between the three Fe compounds. There was, however, a significant association between the iron concentration in the stool and ROS generation.

CONCLUSION

In spite of the differences in their chemical characteristics, none of the three distinct iron complexes reduced oxidative stress in the intestinal lumen.

Oral iron supplements for children in malaria-endemic areas

BACKGROUND

Iron-deficiency anaemia is common during childhood. Iron supplementation has been claimed to increase the risk of malaria.

OBJECTIVES

To assess the effect of iron on malaria and deaths.

SEARCH STRATEGY

We searched The Cochrane Library, PUBMED, MEDLINE, LILACS; and trial registry databases, all up to June 2011. We scanned references of included trials.

SELECTION CRITERIA

Individually and cluster randomized controlled trials conducted in hypoendemic to holoendemic malaria regions and including children below 18 years of age. We included trials comparing orally administered iron, iron with antimalarial treatment, or iron with folic acid versus placebo or no treatment. Iron fortification was excluded. Antihelminthics could be administered to either group. Additional micronutrients had to be administered equally to both groups.

DATA COLLECTION AND ANALYSIS

The primary outcomes were clinical (symptomatic) malaria, severe malaria, and death. Two authors independently selected the studies and extracted the data. We assessed heterogeneity and conducted subgroup analyses by the presence of anaemia at baseline, age, and malaria endemicity. We assessed risk of bias using domain-based evaluation. We performed a fixed-effect meta-analysis for all outcomes and random-effects meta-analysis for hematological outcomes. We adjusted analyses for cluster randomized trials.

MAIN RESULTS

Seventy-one trials (45,353 children) were included. For clinical malaria, no significant difference between iron alone and placebo was detected, (risk ratio (RR) 0.99, 95% confidence intervals (CI) 0.90 to 1.09, 13 trials). The results were similar in the subgroups of non-anaemic children and children below 2 years of age. There was no significant difference in deaths in hyper- and holoendemic areas, risk difference +1.93 per 1000 children (95% CI -1.78 to 5.64, 13 trials, 17,898 children). Iron administered for treatment of anaemia resulted in a larger increase in haemoglobin than iron given for prevention, and the benefit was similar in hyper- or holoendemic and lower endemicity settings. Iron and folic acid supplementation resulted in mixed results for severe malaria. Overall, the risk for clinical malaria was higher with iron or with iron plus folic acid in trials where services did not provide for malaria surveillance and treatment. Iron with antimalarial treatment significantly reduced malaria. Iron supplementation during an acute attack of malaria did not increase the risk for parasitological failure, (RR 0.96, 95% CI 0.74 to 1.24, three trials) or deaths.

AUTHORS' CONCLUSIONS

Iron alone or with antimalaria treatment does not increase the risk of clinical malaria or death when regular malaria surveillance and treatment services are provided. There is no need to screen for anaemia prior to iron supplementation.

Iron, meat and health

This article is a summary of the publication "Iron and Health" by the Scientific Advisory Committee on Nutrition (SACN) to the U.K. Government (2010), which reviews the dietary intake of iron and the impact of different dietary patterns on the nutritional and health status of the U.K. population. It concludes that several uncertainties make it difficult to determine dose-response relationships or to confidently characterize the risks associated with iron deficiency or excess. The publication makes several recommendations concerning iron intakes from food, including meat, and from supplements, as well as recommendations for further research.

Iron supplements reduce the risk of iron deficiency anemia in marginally low birth weight infants

OBJECTIVE

Low birth weight infants are at risk for iron deficiency (ID). Most LBW infants have marginally low birth weight (MLBW, 2000-2500 g) and it is not known whether they benefit from iron supplements. The objective of this trial was to study the effects of iron supplementation in MLBW infants.

METHOD

In a randomized controlled trial, we assigned 285 healthy, MLBW infants to receive iron supplements at a dose of 0 (placebo), 1, or 2 mg/kg per day between 6 weeks and 6 months of age. Hemoglobin levels, ferritin levels, transferrin saturation, mean cell volume, and transferrin receptor levels were analyzed at 6 months. Growth and morbidity were monitored.

RESULTS

Iron supplementation resulted in significant dose-dependent effects on hemoglobin and all iron status indicators at 6 months. The prevalence of ID at 6 months was 36% in the placebo group, 8.2% in the 1 mg/kg per day group, and 3.8% in the 2 mg/kg per day group (P<.001). The prevalence rates of ID anemia (IDA) were 9.9%, 2.7%, and 0%, respectively (P=.004). Among infants who were exclusively breastfed at 6 weeks, the prevalence of IDA was 18% in the placebo group. There were no significant differences between groups in growth or morbidity.

CONCLUSIONS

MLBW infants have relatively high risks of ID and IDA, especially if they are breastfed. Iron supplementation at 2 mg/kg per day from 6 weeks to 6 months reduces this risk effectively, with no short-term adverse effects on morbidity or growth.

Linear and ponderal growth trajectories in well-nourished, iron-sufficient infants are unimpaired by iron supplementation

Iron deficiency remains the most common nutritional deficiency worldwide and supplementation is recommended during periods of high risk, including infancy. However, questions have been raised about possible adverse effects of iron on growth in iron-sufficient (IS) infants and the advisability of across-the-board iron supplementation. This study examined whether short- or long-term growth was impaired in IS infants who received iron supplementation. From a longitudinal study of healthy, breast-fed, low- to middle-income Chilean infants randomly assigned to iron supplementation or usual nutrition at 6 or 12 mo, we retrospectively identified infants meeting criteria for iron sufficiency at the time of random assignment (n = 273). Using multilevel analysis, ponderal and linear growth were modeled before, during, and after iron supplementation up to 10 y in 3 comparisons: 1) iron supplementation compared with usual nutrition from 6 to 12 mo; 2) iron supplementation compared with usual nutrition from 12 to 18 mo; and 3) 15 mg/d of iron as drops compared with iron-fortified formula (12 mg/L). Growth trajectories did not differ during or after supplementation indicating no adverse effect of iron in any comparison. These results suggest that, at least in some environments, iron does not impair growth in IS infants.

Oral iron supplementation for preventing or treating anaemia among children in malaria-endemic areas

BACKGROUND

Iron-deficiency anaemia is common during childhood. Iron supplementation has been claimed to increase the risk of malaria.

OBJECTIVES

To assess the effect of iron on malaria and deaths.

SEARCH STRATEGY

We searched The Cochrane Library (2009, issue 1); MEDLINE; EMBASE; LILACS and metaRegister of Controlled Trials, all up to March 2009. We scanned references of included trials.

SELECTION CRITERIA

Individually and cluster-randomized controlled trials conducted in hypoendemic to holoendemic malaria regions and including children < 18 years. We included trials comparing orally administered iron with or without folic acid vs. placebo or no treatment. Iron fortification was excluded. Antimalarials and/or antiparasitics could be administered to either group. Additional micronutrients could only be administered equally to both groups.

DATA COLLECTION AND ANALYSIS

The primary outcomes were malaria-related events and deaths. Secondary outcomes included haemoglobin, anaemia, other infections, growth, hospitalizations, and clinic visits. We assessed risk of bias using domain-based evaluation. Two authors independently selected studies and extracted data. We contacted authors for missing data. We assessed heterogeneity. We performed fixed-effect meta-analysis and presented random-effects results when heterogeneity was present. We present pooled risk ratios (RR) with 95% confidence intervals (CIs). We used adjusted analyses for cluster-randomized trials.

MAIN RESULTS

Sixty-eight trials (42,981 children) fulfilled the inclusion criteria. Iron supplementation did not increase the risk of clinical malaria (RR 1.00, 95% CI 0.88 to 1.13; 22,724 children, 14 trials, random-effects model). The risk was similar among children who were non-anaemic at baseline (RR 0.96, 95% CI 0.85 to 1.09). An increased risk of malaria with iron was observed in trials that did not provide malaria surveillance and treatment. The risk of malaria parasitaemia was higher with iron (RR 1.13, 95% CI 1.01 to 1.26), but there was no difference in adequately concealed trials. Iron + antimalarial was protective for malaria (four trials). Iron did not increase the risk of parasitological failure when given during malaria (three trials). There was no increased risk of death across all trials comparing iron versus placebo (RR 1.11, 95% CI 0.91 to 1.36; 21,272 children, 12 trials). Iron supplementation increased haemoglobin, with significant heterogeneity, and malaria endemicity did not affect this effect. Growth and other infections were mostly not affected by iron supplementation.

AUTHORS' CONCLUSIONS

Iron does not increase the risk of clinical malaria or death, when regular malaria surveillance and treatment services are provided. There is no need to screen for anaemia prior to iron supplementation.

Iron status of breastfed infants is improved equally by medicinal iron and iron-fortified cereal

BACKGROUND

Although uncommon, iron deficiency (ID) occurs in breastfed infants. The regular provision of iron may prevent ID.

OBJECTIVE

The objective was to test the feasibility and effectiveness of 2 modalities of providing iron (medicinal iron or iron-fortified cereal) to breastfed infants. The study tested the hypothesis that regular provision of iron improves iron status of breastfed infants without adverse effects.

DESIGN

In this prospective, randomized, open-label trial, breastfed infants received on a regular basis either medicinal iron (n = 48) or an iron-fortified fruit-cereal combination (n = 45) from 4 to 9 mo or no intervention (control group; n = 59). The interventions provided 7.0-7.5 mg ferrous sulfate/d. Infants were enrolled at 1 mo and were followed to 2 y. Iron-status indicators were determined periodically, stool characteristics were recorded, and growth was monitored.

RESULTS

The regular provision of iron led to improved iron status during and for some months after the intervention. Both sources of iron were about equally effective. Iron affected stool color but had no effect on feeding-related behavior. However, medicinal iron was associated with a small but significant reduction in length gain and a trend toward reduced weight gain. ID anemia was observed in 4 infants (2.3%), most of whom had a low birth iron endowment. Mild ID was common in the second year of life.

CONCLUSIONS

Regular provision of medicinal iron or iron-fortified cereal improves the iron status of breastfed infants and may prevent ID. Both modalities are equally effective, but medicinal iron leads to somewhat reduced growth. This trial was registered at ClinicalTrials.gov as NCT00760890.