Overweight impairs efficacy of iron supplementation in iron-deficient South African children: a randomized controlled intervention
Date
2013Author
Baumgartner, J.
Smuts, C.M.
Aeberli, I.
Malan, L.
Tjalsma, H.
Zimmermann, M.B.
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BACKGROUND: Many countries in the nutrition transition have high rates of iron deficiency (ID) and overweight (OW). ID is more
common in OW children; this may be due to adiposity-related inflammation reducing iron absorption.
OBJECTIVE: We investigated whether weight status predicts response to oral iron supplementation in ID South African children.
DESIGN: A placebo-controlled trial of oral iron supplementation (50 mg, 4 weeks for 8.5 months) was done in ID 6- to 11-year-old
children (n¼321); 28% were OW or obese. BMI-for-age z-scores (BAZ), hepcidin (in a sub-sample), hemoglobin, serum ferritin (SF),
transferrin receptor (TfR), zinc protoporphyrin (ZnPP) and C-reactive protein (CRP) were measured; body iron was calculated from
the SF to TfR ratio.
RESULTS: At baseline, BAZ correlated with CRP (r¼0.201, Po0.001) and CRP correlated with hepcidin (r¼0.384, Po0.001).
Normal weight children supplemented with iron had significantly lower TfR concentrations at endpoint than the OW children
supplemented with iron and the children receiving placebo. Higher BAZ predicted higher TfR (b¼0.232, Po0.001) and lower body
iron (b¼ 0.090, P¼0.016) at endpoint, and increased the odds ratio (OR) for remaining ID at endpoint in both the iron and
placebo groups (iron: OR 2.31, 95% CI: 1.13, 4.73; placebo: OR 1.78, 95% CI: 1.09, 2.91). In the children supplemented with iron,
baseline hepcidin and BAZ were significant predictors of endpoint TfR, with a trend towards a hepcidin BAZ interaction
(P¼0.058).
CONCLUSION: South African children with high BAZ have a two-fold higher risk of remaining ID after iron supplementation. This
may be due to their higher hepcidin concentrations reducing iron absorption. Thus, the current surge in OW in rapidly developing
countries may undercut efforts to control anemia in vulnerable groups. The trial is registered at clinicaltrials.gov as NCT01092377.
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