Plasma ferritin and soluble transferrin receptor concentrations and body iron stores identify similar risk factors for iron deficiency but result in different estimates of the national prevalence of iron deficiency and iron-deficiency anemia among women and children in Cameroon

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

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

Malian children with moderate acute malnutrition who are treated with lipid-based dietary supplements have greater weight gains and recovery rates than those treated with locally produced cereal-legume products: a community-based, cluster-randomized trial

BACKGROUND

Moderate acute malnutrition (MAM), defined as weight-for-length z score between -3 and -2 or midupper arm circumference between 11.5 and 12.5 cm, affects ∼33 million children aged <5 y worldwide.

OBJECTIVE

The objective was to compare the effects of 4 dietary supplements for the treatment of MAM.

DESIGN

Twelve community health centers in rural Mali were randomly assigned to provide to 1264 MAM children aged 6-35 mo one of 4 dietary supplements containing ∼500 kcal/d for 12 wk: 1) ready-to-use, lipid-based supplementary food (RUSF); 2) special corn-soy blend (CSB++); 3) locally processed, fortified flour (Misola); or 4) locally milled flours plus oil, sugar, and micronutrient powder (LMF).

RESULTS

In total, 1178 children (93.2%) completed the study. The adjusted mean (95% CI) change in weight (kg) from baseline was greater with RUSF than with the locally processed blends and was intermediate with CSB++ [1.16 (1.08, 1.24) for RUSF, 1.04 (0.96, 1.13) for CSB++, 0.91 (0.82, 0.99) for Misola, and 0.83 (0.74, 0.92) for LMF; P < 0.001]. For length change, RUSF and CSB++ differed significantly from LMF. Sustained recovery rates were higher with RUSF (73%) than with Misola (61%) and LMF (58%), P < 0.0001; CSB++ recovery rates (68%) did not differ from any of the other groups.

CONCLUSIONS

RUSF was more effective, but more costly, than other dietary supplements for the treatment of MAM; CSB++ yielded intermediate results. The benefits of treatment should be considered in relation to product costs and availability.

Asymptomatic malaria infection affects the interpretation of biomarkers of iron and vitamin A status, even after adjusting for systemic inflammation, but does not affect plasma zinc concentrations among young children in Burkina Faso

BACKGROUND

Biomarkers of iron [plasma ferritin (pF)], vitamin A [retinol binding protein (RBP)], and zinc status [plasma zinc (pZn)] are affected by the acute phase response, independent of micronutrient status.

OBJECTIVE

The objective of these analyses was to assess how asymptomatic malaria infection affects the interpretation of these biomarkers after adjustment for elevated acute phase proteins (APPs).

METHODS

Soluble transferrin receptor (sTfR), pF, RBP, and pZn concentrations were measured among 451 asymptomatic children aged 6-23 mo in Burkina Faso and adjusted for elevated APP (C-reactive protein ≥5 mg/L and/or α-1-acid-glycoprotein ≥1 g/L) based on a 4-group categorical model. Plasma histidine-rich protein II (HRP2) concentrations ≥0.75 μg/L were considered indicative of current or recent malaria parasitemia.

RESULTS

Of the children in the study, 57.4% had at least 1 elevated APP, and 48.5% had elevated HRP2. After adjusting for APP, children with elevated HRP2 had higher pF (23.5 ± 1.5 μg/L vs. 11.1 ± 0.8 μg/L; P < 0.001) and lower RBP (0.79 ± 0.01 μmol/L vs. 0.92 ± 0.01 μmol/L; P < 0.001) than those without, but there were no differences in pZn among those with and without elevated HRP2 (64.9 ± 12.7 μg/dL vs. 64.9 ± 11.1 μg/dL; P = 0.98). Children with elevated HRP2 had higher sTfR than those without (17.6 ± 0.5 mg/L vs. 12.3 ± 0.4 mg/L; P < 0.0001). After adjusting for HRP2, along with APP, the estimated prevalence of iron deficiency (pF < 12 μg/L) increased from 38.7% to 50.6% and vitamin A deficiency (RBP < 0.84 μmol/L) decreased from 33.4% to 27.7%.

CONCLUSIONS

Asymptomatic malaria is associated with indicators of micronutrient status, even after adjusting for APP. Adjusting indicators of iron and vitamin A status based only on APP may inaccurately estimate the prevalence of micronutrient deficiencies in settings with a high prevalence of malaria and inflammation. This trial was registered at clinicaltrials.gov as NCT00944853.

Food insecurity and nutritional biomarkers in relation to stature in Inuit children from Nunavik

OBJECTIVES

Inuit in Canada experience alarming levels of food insecurity, but nutritional and physiological consequences are poorly documented, especially in school-age children. The objective of this study was to assess the relation of food insecurity to iron deficiency and stature in school-aged Inuit children from Nunavik (Northern Quebec).

METHODS

Food insecurity, iron deficiency, and stature were assessed in a cohort of children. Food insecurity was determined by interviewing the children's mothers. Multiple logistic regression was used to evaluate the association of food insecurity to iron deficiency and short stature. We defined short stature as a height in the lowest tertile for age and sex, based on Canadian growth charts. The relation of food insecurity to height (cm) was analyzed with a general linear model. Statistical models controlled for age, sex, normal/overweight/obese status, prenatal lead exposure and postnatal polychlorinated biphenyls exposure.

RESULTS

Half of the children (49.7%, n=145) were food insecure, while one third were iron depleted, 12.6% had anaemia, and 8.7% had iron-deficiency anaemia. The multivariate odds ratio of anaemia was 1.82 (95% CI: 0.97, 3.42, p=0.06) for food-insecure children. Prevalence of short stature was 18.7%. Food-insecure children were an average of 2 cm shorter (95% CI: -0.48, -3.17) than food-secure children (p<0.01).

CONCLUSION

In this population, food-insecure children have greater burdens of nutritional deficiencies and slower linear growth. Considering the high prevalence of food insecurity among Inuit children in Nunavik, nutritional deficiencies and adverse effects on development should be carefully monitored.

Physiology of iron metabolism

A revolution occurred during the last decade in the comprehension of the physiology as well as in the physiopathology of iron metabolism. The purpose of this review is to summarize the recent knowledge that has accumulated, allowing a better comprehension of the mechanisms implicated in iron homeostasis. Iron metabolism is very fine tuned. The free molecule is very toxic; therefore, complex regulatory mechanisms have been developed in mammalian to insure adequate intestinal absorption, transportation, utilization, and elimination. 'Ironomics' certainly will be the future of the understanding of genes as well as of the protein-protein interactions involved in iron metabolism.

The value of Ret-Hb and sTfR in the diagnosis of iron depletion in healthy, young children

OBJECTIVES

Reticulocyte hemoglobin (Ret-Hb) content and soluble transferrin receptor (sTfR) are described as promising biomarkers in the analysis of iron status. However, the value of Ret-Hb and sTfR in the early detection of iron depletion, as frequently observed in children in high-income countries, is unclear. We hypothesized that young children to iron depletion, using the WHO cutoff of ferritin <12 μg/l, would have lower Ret-Hb and higher sTfR concentrations compared to children with a ferritin ⩾level 12 μg/l.

SUBJECTS/METHODS

In this cross-sectional study, we analyzed mean concentrations of Ret-Hb and sTfR in 351 healthy children aged 0.5-3 years in a high-income country. The Student's t-test was used to compare Ret-Hb and sTfR concentrations between groups.

RESULTS

We showed that concentrations of Ret-Hb and sTfR are similar in children with and without iron depletion. A decrease in Ret-Hb concentration was present only when ferritin concentrations were <8 μg/l. sTfR concentrations were similar in children with ferritin concentrations <6 μg/l and ⩾12 μg/l.

CONCLUSIONS

Our results showed that the discriminative value of Ret-Hb and sTfR for the detection of iron depletion is limited. Our findings suggest that ferritin is the most useful biomarker in the screening of iron depletion in healthy children in high-income countries. However, ideally, reference ranges of iron status biomarkers should be based on studies showing that children with concentrations outside reference ranges have poor neurodevelopmental outcomes.

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

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

Iron in child obesity. Relationships with inflammation and metabolic risk factors

Iron (Fe) sequestration is described in overweight and in its associated metabolic complications, i.e., metabolic syndrome (MetS) and non-alcoholic liver fatty disease (NAFLD); however, the interactions between Fe, obesity and inflammation make it difficult to recognize the specific role of each of them in the risk of obesity-induced metabolic diseases. Even the usual surrogate marker of Fe stores, ferritin, is influenced by inflammation; therefore, in obese subjects inflammation parameters must be measured together with those of Fe metabolism. This cross-sectional study in obese youth (502 patients; 57% girls): 11.4 ± 3.0 years old (x ± SD); BMI z score 5.5 ± 2.3), multivariate regression analysis showed associations between Fe storage assessed by serum ferritin with risk factors for MetS and NAFLD, assessed by transaminase levels, which were independent of overweight and the acute phase protein fibrinogen. Further studies incorporating the measurement of complementary parameters of Fe metabolism could improve the comprehension of mechanisms involved.