Iron and malaria: absorption, efficacy and safety

Subnational mapping for targeting anaemia prevention in women of reproductive age in Ethiopia: A coverage-equity paradox

Anaemia in women of reproductive age (WRA) can be effectively addressed if supported by a better understanding of the spatial variations, magnitude, severity and distribution of anaemia. This study aimed to map the subnational spatial distribution of anaemia (any, moderate and severe forms) among WRA in Ethiopia. We identified and mapped (any, moderate and severe) anaemia hotspots in WRA (n = 14,923) at the subnational level and identified risk factors using multilevel logistic regression. Kulldorff scan statistics were used to identify hotspot regions. Ordinary kringing was used to predict the anaemia prevalence in unmeasured areas. The overall anaemia prevalence increased from 16.6% in 2011 to 23.6% in 2016, a rise that was mostly related to the widening of existing hotspot areas. The primary clusters of (any) anaemia were in Somali and Afar regions. The horn of the Somali region represented a cluster of 330 km where 10% of WRA were severely anaemic. The Oromia-Somali border represented a significant cluster covering 247 km, with 9% severe anaemia. Population-dense areas with low anaemia prevalence had high absolute number of cases. Women education, taking iron-folic-acid tablets during pregnancy and birth-delivery in health facilities reduced the risk of any anaemia (P < 0.05). The local-level mapping of anaemia helped identify clusters that require attention but also highlighted the urgent need to study the aetiology of anaemia to improve the effectiveness and safety of interventions. Both relative and absolute anaemia estimates are critical to determine where additional attention is needed.

Biology of Anemia: A Public Health Perspective

Our goal is to present recent progress in understanding the biological mechanisms underlying anemia from a public health perspective. We describe important advances in understanding common causes of anemia and their interactions, including iron deficiency (ID), lack of other micronutrients, infection, inflammation, and genetic conditions. ID develops if the iron circulating in the blood cannot provide the amounts required for red blood cell production and tissue needs. ID anemia develops as iron-limited red blood cell production fails to maintain the hemoglobin concentration above the threshold used to define anemia. Globally, absolute ID (absent or reduced body iron stores that do not meet the need for iron of an individual but may respond to iron supplementation) contributes to only a limited proportion of anemia. Functional ID (adequate or increased iron stores that cannot meet the need for iron because of the effects of infection or inflammation and does not respond to iron supplementation) is frequently responsible for anemia in low- and middle-income countries. Absolute and functional ID may coexist. We highlight continued improvement in understanding the roles of infections and inflammation in causing a large proportion of anemia. Deficiencies of nutrients other than iron are less common but important in some settings. The importance of genetic conditions as causes of anemia depends upon the specific inherited red blood cell abnormalities and their prevalence in the settings examined. From a public health perspective, each setting has a distinctive composition of components underlying the common causes of anemia. We emphasize the coincidence between regions with a high prevalence of anemia attributed to ID (both absolute and functional), those with endemic infections, and those with widespread genetic conditions affecting red blood cells, especially in sub-Saharan Africa and regions in Asia and Oceania.

Approaches to Address the Anemia Challenge

Anemia is a multifactorial condition; approaches to address it must recognize that the causal factors represent an ecology consisting of internal (biology, genetics, and health) and external (social/behavioral/demographic and physical) environments. In this paper, we present an approach for selecting interventions, followed by a description of key issues related to the multiple available interventions for prevention and reduction of anemia. We address interventions for anemia using the following 2 main categories: 1) those that address nutrients alone, and, 2) those that address nonnutritional causes of anemia. The emphasis will be on interventions of public health relevance, but we also consider the clinical context. We also focus on interventions at different stages of the life course, with a particular focus on women of reproductive age and preschool-age children, and present evidence on various factors to consider when selecting an intervention-inflammation, genetic mutations, nutrient delivery, bioavailability, and safety. Each section on an intervention domain concludes with a brief discussion of key research areas.

Safe and effective delivery of supplemental iron to healthy adults: a two-phase, randomized, double-blind trial - the safe iron study

Introduction

The safety of novel forms of iron in healthy, iron-replete adults as might occur if used in population-based iron supplementation programs was examined. We tested the hypotheses that supplementation with nanoparticulate iron hydroxide adipate tartrate (IHAT), an iron-enriched Aspergillus oryzae product (ASP), or ferrous sulphate heptahydrate (FS) are safe as indicated by erythrocyte susceptibility to malarial infection, bacterial proliferation, and gut inflammation. Responses to FS administered daily or weekly, and with or without other micronutrients were compared.

Methods

Two phases of randomized, double-blinded trials were conducted in Boston, MA. Phase I randomized 160 volunteers to six treatments: placebo, IHAT, ASP, FS, and FS plus a micronutrient powder (MNP) administrated daily at 60 mg Fe/day; and FS administered as a single weekly dose of 420 mg Fe. Phase II randomized 86 volunteers to IHAT, ASP, or FS administered at 120 mg Fe/day. Completing these phases were 151 and 77 participants, respectively. The study was powered to detect effects on primary endpoints: susceptibility of participant erythrocytes to infection by Plasmodium falciparum, the proliferation potential of selected pathogenic bacteria in sera, and markers of gut inflammation. Secondary endpoints for which the study was not powered included indicators of iron status and gastrointestinal symptoms.

Results

Supplementation with any form of iron did not affect any primary endpoint. In Phase I, the frequency of gastrointestinal symptoms associated with FS was unaffected by dosing with MNP or weekly administration; but participants taking IHAT more frequently reported abdominal pain (27%, p < 0.008) and nausea (4%, p = 0.009) than those taking FS, while those taking ASP more frequently reported nausea (8%, p = 0.009). Surprisingly, only 9% of participants taking IHAT at 120 mg Fe/day (Phase II) reported abdominal pain and no other group reported that symptom.

Discussion

With respect to the primary endpoints, few differences were found when comparing these forms of iron, indicating that 28 days of 60 or 120 mg/day of IHAT, ASP, or FS may be safe for healthy, iron-replete adults. With respect to other endpoints, subjects receiving IHAT more frequently reported abdominal pain and nausea, suggesting the need for further study.

Clinical Trial Registration

ClinicalTrials.gov, NCT03212677; registered: 11 July 2017.

Safe and effective delivery of supplemental iron to healthy older adults: The double-blind, randomized, placebo-controlled trial protocol of the Safe Iron Study

The forms of iron currently available to correct iron deficiency have adverse effects, including infectious diarrhea, increased susceptibility to malaria, inflammation and detrimental changes to the gut microbiome. These adverse effects limit their use such that the growing burden of iron deficiency has not abated in recent decades. Here, we summarize the protocol of the "Safe Iron Study", the first clinical study examining the safety and efficacy of novel forms of iron in healthy, iron-replete adults. The Safe Iron Study is a double-blind, randomized, placebo-controlled trial conducted in Boston, MA, USA. This study compares ferrous sulfate heptahydrate (FeSO 4·H 2O) with two novel forms of iron supplements (iron hydroxide adipate tartrate (IHAT) and organic fungal iron metabolite (Aspiron™ Natural Koji Iron)). In Phase I, we will compare each source of iron administrated at a low dose (60 mg Fe/day). We will also determine the effect of FeSO 4 co-administrated with a multiple micronutrient powder and weekly administration of FeSO 4. The forms of iron found to produce no adverse effects, or adverse effects no greater than FeSO 4 in Phase I, Phase II will evaluate a higher, i.e., a therapeutic dose (120 mg Fe/day). The primary outcomes of this study include ex vivo malaria ( Plasmodium falciparum) infectivity of host erythrocytes, ex vivo bacterial proliferation (of selected species) in presence of host plasma and intestinal inflammation assessed by fecal calprotectin. This study will test the hypotheses that the novel forms of iron, administered at equivalent doses to FeSO 4, will produce similar increases in iron status in iron-replete subjects, yet lower increases in ex vivo malaria infectivity, ex vivo bacterial proliferation, gut inflammation. Ultimately, this study seeks to contribute to development of safe and effective forms of supplemental iron to address the global burden of iron deficiency and anemia. Registration: ClinicalTrials.gov identifier: NCT03212677; registered: 11 July 2017.

Impact of Iron-Enriched Aspergillus oryzae on Iron Bioavailability, Safety, and Gut Microbiota in Rats

Iron deficiency is a leading global nutritional problem. Ferrous sulfate (FeSO₄) is the most common iron source used for supplementation. Because of many side effects associated with its consumption, it is important to identify new forms of iron. The objectives of this study were to assess the bioavailability of iron-enriched Aspergillus oryzae, Aspiron (ASP), evaluate the toxicity of high-dose iron supplementation with ASP, and determine the ASP impact on gut microbiota in rats. In this study, we investigated iron bioavailability using the hemoglobin repletion test. Aspartate aminotransferase, alanine aminotransferase, and blood urea nitrogen levels were determined to evaluate the effect on liver and kidney functions. Protein carbonyls were measured to assess oxidative damage to proteins. Fecal samples at the end of the 14 day repletion period were used for 16S rRNA sequencing for gut microbiota analysis. The slope ratio method using a common intercept linear regression model was used to compare the bioavailability of ASP to FeSO₄. Iron repletion increased hemoglobin concentrations with both ASP and FeSO₄ treatments compared to the control group, except in the lowest ASP group. The slope ratio indicated that relative iron bioavailability of ASP was 60% of that of FeSO₄ when hemoglobin change was compared to iron in the diet. Similar results were obtained when absolute iron intake was compared on the basis of food consumption. In comparison to the control, protein carbonyl concentrations were significantly ( p < 0.05) higher in the FeSO₄ group but not with the ASP group. Supplementation with both sources of iron reduced the Enterobacteriaceae population in the gut microbiota of the rats. A higher relative abundance of bacteria from the phylum Verrucomicrobia was also observed with the highest dose of ASP. Iron-enriched A. oryzae with 60% relative bioavailability of FeSO₄ did not show any signs of adverse effects after 14 days of iron supplementation. Future human studies are needed to understand the ASP detailed effect on gut microbiota.

Point-of-use fortification of foods with micronutrient powders containing iron in children of preschool and school-age

BACKGROUND

Approximately 600 million children of preschool and school age are anaemic worldwide. It is estimated that at least half of the cases are due to iron deficiency. Point-of-use fortification of foods with micronutrient powders (MNP) has been proposed as a feasible intervention to prevent and treat anaemia. It refers to the addition of iron alone or in combination with other vitamins and minerals in powder form, to energy-containing foods (excluding beverages) at home or in any other place where meals are to be consumed. MNPs can be added to foods either during or after cooking or immediately before consumption without the explicit purpose of improving the flavour or colour.

OBJECTIVES

To assess the effects of point-of-use fortification of foods with iron-containing MNP alone, or in combination with other vitamins and minerals on nutrition, health and development among children at preschool (24 to 59 months) and school (five to 12 years) age, compared with no intervention, a placebo or iron-containing supplements.

SEARCH METHODS

In December 2016, we searched the following databases: CENTRAL, MEDLINE, Embase, BIOSIS, Science Citation Index, Social Science Citation Index, CINAHL, LILACS, IBECS, Popline and SciELO. We also searched two trials registers in April 2017, and contacted relevant organisations to identify ongoing and unpublished trials.

SELECTION CRITERIA

Randomised controlled trials (RCTs) and quasi-RCTs trials with either individual or cluster randomisation. Participants were children aged between 24 months and 12 years at the time of intervention. For trials with children outside this age range, we included studies where we were able to disaggregate the data for children aged 24 months to 12 years, or when more than half of the participants were within the requisite age range. We included trials with apparently healthy children; however, we included studies carried out in settings where anaemia and iron deficiency are prevalent, and thus participants may have had these conditions at baseline.

DATA COLLECTION AND ANALYSIS

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

MAIN RESULTS

We included 13 studies involving 5810 participants from Latin America, Africa and Asia. We excluded 38 studies and identified six ongoing/unpublished trials. All trials compared the provision of MNP for point-of-use fortification with no intervention or placebo. No trials compared the effects of MNP versus iron-containing supplements (as drops, tablets or syrup).The sample sizes in the included trials ranged from 90 to 2193 participants. Six trials included participants younger than 59 months of age only, four included only children aged 60 months or older, and three trials included children both younger and older than 59 months of age.MNPs contained from two to 18 vitamins and minerals. The iron doses varied from 2.5 mg to 30 mg of elemental iron. Four trials reported giving 10 mg of elemental iron as sodium iron ethylenediaminetetraacetic acid (NaFeEDTA), chelated ferrous sulphate or microencapsulated ferrous fumarate. Three trials gave 12.5 mg of elemental iron as microencapsulated ferrous fumarate. Three trials gave 2.5 mg or 2.86 mg of elemental iron as NaFeEDTA. One trial gave 30 mg and one trial provided 14 mg of elemental iron as microencapsulated ferrous fumarate, while one trial gave 28 mg of iron as ferrous glycine phosphate.In comparison with receiving no intervention or a placebo, children receiving iron-containing MNP for point-of-use fortification of foods had lower risk of anaemia prevalence ratio (PR) 0.66, 95% confidence interval (CI) 0.49 to 0.88, 10 trials, 2448 children; moderate-quality evidence) and iron deficiency (PR 0.35, 95% CI 0.27 to 0.47, 5 trials, 1364 children; moderate-quality evidence) and had higher haemoglobin (mean difference (MD) 3.37 g/L, 95% CI 0.94 to 5.80, 11 trials, 2746 children; low-quality evidence).Only one trial with 115 children reported on all-cause mortality (zero cases; low-quality evidence). There was no effect on diarrhoea (risk ratio (RR) 0.97, 95% CI 0.53 to 1.78, 2 trials, 366 children; low-quality evidence).

AUTHORS' CONCLUSIONS

Point-of-use fortification of foods with MNPs containing iron reduces anaemia and iron deficiency in preschool- and school-age children. However, information on mortality, morbidity, developmental outcomes and adverse effects is still scarce.

Hair Mercury Level is Associated with Anemia and Micronutrient Status in Children Living Near Artisanal and Small-Scale Gold Mining in the Peruvian Amazon

Anemia has been widely studied in global health contexts because of severe nutritional deficiency, and more recently, inflammatory status, but chemical exposures are rarely considered. Until recently, "anemia" was used synonymously with "iron deficiency anemia (IDA)" in global health settings. However, only 50% of anemia cases worldwide are IDA. Environmental toxicology studies of anemia risk have generally focused on populations in developed countries, albeit with high exposure to environmental toxicants, such as lead or cadmium. In the developing world, toxicant exposures commonly coexist with other risk factors for anemia. In particular, artisanal and small-scale gold mining (ASGM) communities are at risk for dietary methylmercury exposure through contaminated fish consumption, and for anemia due to food insecurity and infectious and chronic diseases. Here, we report analysis of total hair mercury content, hemoglobin, and serum micronutrient levels in children < 12 years of age (N = 83) near ASGM in the Peruvian Amazon. Forty-nine percent (N = 29/59) of those aged < 5 years were anemic (< 11 g/dL) and 52% (N = 12/23) of those aged 5-11 years (< 11.5 g/dL). Few children were stunted, wasted, or micronutrient deficient. Median total hair mercury was 1.18 μg/g (range: 0.06-9.70 μg/g). We found an inverse association between total mercury and hemoglobin (β = -0.12 g/dL, P = 0.06) that persisted (β = -0.14 g/dL, P = 0.04) after adjusting for age, sex, anthropometrics, and vitamin B₁₂ in multivariate regression. This study provides preliminary evidence that methylmercury exposure is associated with anemia, which is especially relevant to children living near ASGM.

High Iron Levels Are Associated with Increased Malaria Risk in Infants during the First Year of Life in Benin

The World Health Organization (WHO) estimates that 40% of children in low-income countries are anemic. Therefore, iron supplements are recommended by WHO in areas with high anemia rates. However, some studies have set into question the benefits of iron supplementation in malaria-endemic regions. In Benin, a west African country with high prevalence of anemia and malaria, no iron supplements are given systematically to infants so far despite the WHO recommendations. In this context, we wanted to investigate the effect of iron levels during the first year of life on malarial risk in Benin considering complementary risk factors. We followed 400 women and their offspring between January 2010 and June 2012 in Allada (Benin). Environmental, obstetric, and numerous clinical, maternal, and infant risk factors were considered. In multilevel models, high iron levels were significantly associated with the risk of a positive blood smear (adjusted odds ratio = 2.90, P < 0.001) and Plasmodium falciparum parasitemia (beta estimate = 0.38, P < 0.001). Infants with iron levels in the lowest quartile were less likely to have a positive blood smear (P < 0.001), and the risk increased with higher iron levels. Our results appeal for additional evaluation of the effect of different doses of iron supplements on the infant health status, including malaria incidence. Thus, the health status of infants should be compared between cohorts where iron is given either for prevention or anemia treatment, to better understand the effect of iron supplements on infant health.

The iron chaperone poly(rC)-binding protein 2 forms a metabolon with the heme oxygenase 1/cytochrome P450 reductase complex for heme catabolism and iron transfer

Mammals incorporate a major proportion of absorbed iron as heme, which is catabolized by the heme oxygenase 1 (HO1)-NADPH-cytochrome P450 reductase (CPR) complex into biliverdin, carbon monoxide, and ferrous iron. Moreover, intestinal iron is incorporated as ferrous iron, which is transported via the iron importer, divalent metal transporter 1 (DMT1). Recently, we demonstrated that the iron chaperone poly(rC)-binding protein 2 (PCBP2) can directly receive ferrous iron from DMT1 or transfer iron to the iron exporter, ferroportin 1. To promote intracellular iron flux, an iron chaperone may be essential for receiving iron generated by heme catabolism, but this hypothesis is untested so far. Herein, we demonstrate that HO1 binds to PCBP2, but not to other PCBP family members, namely PCBP1, PCBP3, or PCBP4. Interestingly, HO1 formed a complex with either CPR or PCBP2, and it was demonstrated that PCBP2 competes with CPR for HO1 binding. Using PCBP2-deletion mutants, we demonstrated that the PCBP2 K homology 3 domain is important for the HO1/PCBP2 interaction. In heme-loaded cells, heme prompted HO1-CPR complex formation and decreased the HO1/PCBP2 interaction. Furthermore, in vitro reconstitution experiments with purified recombinant proteins indicated that HO1 could bind to PCBP2 in the presence of heme, whereas loading of PCBP2 with ferrous iron caused PCBP2 to lose its affinity for HO1. These results indicate that ferrous iron released from heme can be bound by PCBP2 and suggest a model for an integrated heme catabolism and iron transport metabolon.

Iron and malaria: a dangerous liaison?

Malaria increases the burden of anemia in low-income countries, where, according to 2012 data from the World Health Organization, 40% of children are anemic. Moreover, iron is a cofactor for Plasmodium falciparum development, raising fears that iron supplementation might be harmful in patients with P. falciparum infection. The primary objective of this narrative review is to describe current knowledge on the iron-malaria association, including recent findings and substantive qualitative results. Between 2012 and 2016 the MEDLINE database was searched for literature published about malaria and iron levels. Observational studies reported some protection of iron supplementation against malaria among iron-deficient children, while older clinical trials reported increased susceptibility to malaria among iron-supplemented children. However, iron supplements were not significantly associated with increased malaria risk in recent clinical trials or in a 2016 Cochrane review. Evidence of an iron-malaria association is limited by the following factors: the protective effect of control interventions, the limited follow-up of children, and the lack of homogenous iron indicators. The effects of previous health status and possible thresholds in iron levels should be investigated using a gold-standard combination of iron markers. Moreover, the benefits of iron supplementation require further evaluation.

Anemia, Micronutrient Deficiencies, and Malaria in Children and Women in Sierra Leone Prior to the Ebola Outbreak - Findings of a Cross-Sectional Study

To identify the factors associated with anemia and to document the severity of micronutrient deficiencies, malaria and inflammation, a nationally representative cross-sectional survey was conducted. A three-stage sampling procedure was used to randomly select children <5 years of age and adult women from households in two strata (urban and rural). Household and individual data were collected, and blood samples from children and women were used to measure the prevalence of malaria, inflammation, and deficiencies of iron, vitamin A, folate, and vitamin B12. 839 children and 945 non-pregnant women were included in the survey. In children, the prevalence rates of anemia (76.3%; 95% CI: 71.8, 80.4), malaria (52.6%; 95% CI: 46.0, 59.0), and acute and chronic inflammation (72.6%; 95% CI: 67.5, 77.1) were high. However, the prevalence of vitamin A deficiency (17.4%; 95% CI: 13.9, 21.6) was moderate, and the prevalence of iron deficiency (5.2%; 95% CI: 3.3, 8.1) and iron-deficiency anemia (3.8%; 95% CI: 2.5, 5.8) were low. Malaria and inflammation were associated with anemia, yet they explained only 25% of the population-attributable risk. In women, 44.8% (95% CI: 40.1, 49.5), 35.1% (95% CI: 30.1, 40.4), and 23.6% (95% CI: 20.4, 27.3) were affected by anemia, malaria, or inflammation, respectively. The prevalence rates of iron deficiency (8.3%; 95% CI: 6.2, 11.1), iron-deficiency anemia (6.1%; 95% CI: 4.4, 8.6), vitamin A deficiency (2.1%; 95% CI: 1.1, 3.1) and vitamin B12 deficiency (0.5%; 95% CI: 0.2, 1.4) were low, while folate deficiency was high (79.2%; 95% CI: 74.1, 83.5). Iron deficiency, malaria, and inflammation were significantly associated with anemia, but explained only 25% of cases of anemia. Anemia in children and women is a severe public health problem in Sierra Leone. Since malaria and inflammation only contributed to 25% of anemia, other causes of anemia, such as hemoglobinopathies, should also be explored.

Does Iron Increase the Risk of Malaria in Pregnancy?

Background.  Pregnancy-associated malaria (PAM) remains a significant health concern in sub-Saharan Africa. Cross-sectional studies report that iron might be associated with increased malaria morbidity, raising fears that current iron supplementation policies will cause harm in the present context of increasing resistance against intermittent preventive treatment in pregnancy (IPTp). Therefore, it is necessary to assess the relation of iron levels with malaria risk during the entire pregnancy. Methods.  To investigate the association of maternal iron levels on malaria risk in the context of an IPTp clinical trial, 1005 human immunodeficiency virus-negative, pregnant Beninese women were monitored throughout their pregnancy between January 2010 and May 2011. Multilevel models with random intercept at the individual levels and random slope for gestational age were used to analyze the factors associated with increased risk of a positive blood smear and increased Plasmodium falciparum density. Results.  During the follow-up, 29% of the women had at least 1 episode of malaria. On average, women had 0.52 positive smears (95% confidence interval [CI], 0.44-0.60). High iron levels (measured by the log10 of ferritin corrected on inflammation) were significantly associated with increased risk of a positive blood smear (adjusted odds ratio = 1.75; 95% CI, 1.46-2.11; P < .001) and high P falciparum density (beta estimate = 0.22; 95% CI, 0.18-0.27; P < .001) during the follow-up period adjusted on pregnancy parameters, comorbidities, environmental and socioeconomic indicators, and IPTp regime. Furthermore, iron-deficient women were significantly less likely to have a positive blood smear and high P falciparum density (P < .001 in both cases). Conclusions.  Iron levels were positively associated with increased PAM during pregnancy in the context of IPTp. Supplementary interventional studies are needed to determine the benefits and risks of differently dosed iron and folate supplements in malaria-endemic regions.

The effect of timing of iron supplementation on iron absorption and haemoglobin in post-malaria anaemia: a longitudinal stable isotope study in Malawian toddlers

Background

In sub-Saharan Africa, children with Plasmodium falciparum malaria and anaemia are often given iron supplementation at the time of malaria treatment. Inflammation during and after malaria may decrease iron absorption, thus, absorption might be improved if the start of supplementation is delayed. The study objective was to measure iron absorption from iron supplements started immediately or delayed by two weeks after completion of therapy against uncomplicated P. falciparum malaria.

Methods

Malawian toddlers (n = 48; age 12–24 months) were alternatively assigned to two groups according to their appearance at the health centre: group A was provided iron supplements (30 mg Fe daily) as a FeSO₄-containing syrup for eight weeks starting immediately after malarial treatment; group B was given the iron after a two-week delay. Iron absorption from the syrup was measured on the first day of iron supplementation, and after two and eight weeks in both groups. Haemoglobin (Hb), iron status and inflammation were assessed every two weeks. Fractional iron absorption at each time point and cumulative absorption was quantified by measuring erythrocyte incorporation of ⁵⁷Fe and compared using mixed models.

Results

Comparing group A and B, geometric mean iron absorption did not differ on the first day of supplementation (9.0% vs. 11.4%, P = 0.213) and cumulative iron absorption from the three time points did not differ (6.0% vs. 7.2%, P = 0.124). Hb concentration increased in both groups two weeks after malaria treatment (P < 0.001) and did not differ after eight weeks of supplementation (P = 0.542).

Conclusions

In anaemic toddlers after uncomplicated malaria, a two-week delay in starting iron supplementation did not significantly increase iron absorption or Hb concentration. Iron absorption is sufficiently high in the immediate post-malaria period to warrant supplementation. These findings suggest there is no need to change the current practice of immediate iron supplementation in this setting.

Trial registration

This trial was registered at Pan African Clinical Trials Registry (pactr.org) as PACTR2010050002141682.

Iron deficiency and anemia control for infants and young children in malaria-endemic areas: a call to action and consensus among the research community

WHO recommendations on iron supplementation for infants and young children in malaria-endemic areas changed dramatically from universal to targeted supplementation for iron-deficient children only, after a trial in a high malaria transmission area showed an increased risk of hospital admission and mortality among iron-replete children following iron and folic acid supplementation. Since this time, there has been much debate and little agreement among the nutrition research community on how to move forward, and country policy and program decision makers have been left with incomplete guidance on how to address young child iron deficiency and anemia in their countries. The focus of a recent symposium during the American Society for Nutrition annual meeting, held in Washington, DC, in April 2011, was on exploring options for addressing iron deficiency and anemia among infants and young children in malaria-endemic areas, now, with safe, effective, and feasible interventions that provide iron. Papers based on the invited presentations are included in this supplement. The first paper is a review of the relationship between iron and malaria. The second is an analysis of theoretical and practical considerations regarding the targeted approach of providing iron and includes results from field testing noninvasive screening devices. This is followed by a review of the safety of universal provision of iron through home-fortification products in malaria-endemic areas. The final papers provide a call to action by highlighting pending research issues (fourth paper) and feasible strategies to move programs forward (fifth paper).

Iron and malaria interactions: research needs from basic science to global policy

The resurgence in interest and concern regarding the potentially malign interactions between iron administration and malaria infections, especially in young children and pregnant women, has generated a research agenda that is both broad and deep. This paper highlights some of the key questions under 5 headings: basic science; clinical science and epidemiology; technological developments; country level planning; and global policy. At a time of unparalleled progress in basic science, which is illuminating the mechanisms by which iron interacts with infectious organisms, it is concluded that there are good medium-term prospects for achieving policy breakthroughs based on a secure foundation of disease-nutrient interactions. However, it is also stressed that there is much that can be done in the interim, especially in relation to health systems and implementation research that can empower systems to integrate iron interventions with programs for malaria prevention, surveillance, and treatment.

Safety of universal provision of iron through home fortification of complementary foods in malaria-endemic areas

Home fortification of complementary foods with iron and other micronutrients is a low-cost strategy for filling nutrient gaps in the diets of infants and young children, but there has been uncertainty about the safety of universal provision of iron via home fortification in malaria-endemic areas. Based on the current understanding of the potential mechanisms of adverse effects of iron, the risk can probably be minimized by using the lowest possible efficacious dose of iron, preferably delivered in small amounts throughout the day with food, to minimize spikes in plasma nontransferrin-bound iron and large amounts of unabsorbed iron in the gastrointestinal tract. Results from 6 home fortification studies in malaria-endemic areas showed no increased risk of morbidity (including malaria), but these studies were not powered to rule out a modest increase in the risk of severe adverse events. At present, the safest option is to implement home fortification in the context of comprehensive malaria control strategies, as recommended in recent WHO guidelines.

Safety and efficacy of iron supplements in malaria-endemic areas

Where malaria surveillance and health care is inadequate, iron supplements given without food can increase the severity of malarial infections. The likely explanation is that the rate of iron influx into the plasma from high-dose oral supplements exceeds the rate of iron binding to transferrin and a quantity of non-transferrin-bound iron (NTBI) is formed. It is proposed that NTBI increases the intensity of malarial infections by increasing the sequestration of malaria-infected red cells in the capillaries of the brain and intestine, causing more cerebral malaria and further increasing the permeability of the intestinal barrier to the passage of pathogens. Bacteremia is frequently reported in children with severe malaria. At the same time, high iron doses stimulate the growth of pathogenic bacteria in the stool, further increasing the potential for bacteremia. The normal immune response to malaria, as well as other infections and inflammatory disorders, is to prevent further microbial growth by stimulating hepcidin synthesis and preventing the passage of iron into the plasma. Iron absorption is decreased and the efficacy of the iron interventions would be expected to be lower in the presence of infections.

Early child growth: how do nutrition and infection interact?

It is well known that the relationship between child nutrition and infection is bidirectional, i.e. frequent illness can impair nutritional status and poor nutrition can increase the risk of infection. What is less clear is whether infection reduces the effectiveness of nutrition interventions or, vice versa, whether malnutrition lessens the impact of infection control strategies. The objective of this paper is to review the evidence regarding this interaction between nutrition and infection with respect to child growth in low-income populations. Even when there are no obvious symptoms, physiological conditions associated with infections can impair growth by suppressing appetite, impairing absorption of nutrients, increasing nutrient losses and diverting nutrients away from growth. However, there is little direct evidence that nutrition interventions are less effective when infection is common; more research is needed on this question. On the other hand, evidence from four intervention trials suggests that the adverse effects of certain infections (e.g. diarrhoea) on growth can be reduced or eliminated by improving nutrition. Interventions that combine improved nutrition with prevention and control of infections are likely to be most effective for enhancing child growth and development.