Research Article: Subclinical inflammation influences the association between vitamin A- and iron status among schoolchildren in Ghana

Date Published: February 2, 2017

Publisher: Public Library of Science

Author(s): Abdul-Razak Abizari, Fusta Azupogo, Inge D. Brouwer, Frank Wieringa.

http://doi.org/10.1371/journal.pone.0170747

Abstract

In resource-poor settings, micronutrient deficiencies such as vitamin A deficiency may co-exist with iron-deficiency. In this study we assessed the iron and vitamin A status of schoolchildren and the association between vitamin A and iron status.

A cross-sectional design using the baseline data of a dietary intervention trial conducted among randomly selected 5–12 years old schoolchildren (n = 224) from 2 rural schools in northern Ghana. Hemoglobin (Hb), serum ferritin (SF) and serum transferrin receptor (sTfR) concentrations were used as measures of iron status. Retinol binding protein (RBP) was used as a measure of vitamin A status. Subclinical inflammation (SCI) was measured using C-reactive protein (CRP) and α1-acid glycoprotein (AGP) concentrations. We examined the cross-sectional association between vitamin A and iron status biomarkers with multiple linear regressions.

The proportions of schoolchildren with anemia (WHO criteria), iron-deficiency (ID, SF <15μg/l and/or sTfR >8.5mg/l) and iron-deficiency anemia (IDA, concurrent anemia and ID) were 63.8%, 68.3% and 46.4% respectively. Low or marginal vitamin A status (0.70 μmol/l ≤ RBP < 1.05μmol/l) was present in 48.2% while 37.5% of the schoolchildren had vitamin A deficiency (VAD, RBP <0.70 μmol/l). The prevalence of SCI as well as concurrent VAD and ID were 48.7% and 25% respectively. RBP was associated with Hb (β = 7.2, P = 0.05) but not SF (β = 20.7, P = 0.33) and sTfR concentration (β = 12.0, P = 0.63). In the presence of SCI, RBP was not associated with hemoglobin status but a significant positive association was observed among children without SCI. The study shows that RBP is significantly associated with Hb concentration but not with SF and sTfR. The observed relationship between RBP and Hb is only significant in the absence of SCI.

Partial Text

Multiple micronutrient deficiencies are common in resource poor settings [1–3]. These micronutrient deficiencies are a result of inadequate consumption of nutrient-rich foods, presence of diseases and inefficient utilization of available micronutrients[4,5]. One of the important vulnerable groups, but often neglected by public health interventions, is school-aged children. Recent studies have emphasized the importance of micronutrient deficiencies among school-aged children as they are particularly vulnerable [3,6]. Iron deficiency (ID) co-exists with vitamin A deficiency (VAD) [6–8]. Concurrent deficiencies of vitamin A and iron have been found among school-aged children in Africa [9,10].

From Table 1, the mean Hb was 109.3 ± 13.4 g/l whilst the median (IQR) for SF and sTfR were 44.8 (29.7 to 93.9) μg/l and 10.1(8.1 to 13.2) mg/l respectively. Overall, 63.8% of the schoolchildren were anemic. Using a cut-off value of <15μg/l for SF concentration, 7.1% of the children had ID and this proportion increased to 8.9% after correction with factors proposed by Thurnham. ID differed widely if based on SF or sTfR (7.1% vs. 68.3%). The overall prevalence of ID defined as SF <15μg/l and/or sTfR > 8.5 g/l was 68.3%.

The study shows that RBP is significantly associated with Hb concentration but not with SF and sTfR. The observed relationship between RBP and Hb is only significant in the absence of SCI.

 

Source:

http://doi.org/10.1371/journal.pone.0170747

 

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