Increased Iron Status during a Feeding Trial of Iron-Biofortified Beans Increases Physical Work Efficiency in Rwandan Women

Sarah V Luna,Laura M Pompano,Mercy Lung'Aho,Jean Bosco Gahutu,Jere D Haas

doi:10.1093/jn/nxaa016

Abstract

ABSTRACTBackgroundIron-biofortified staple foods can improve iron status and resolve iron deficiency. However, whether improved iron status from iron biofortification can improve physical performance remains unclear.ObjectiveThis study aimed to examine whether changes in iron status from an iron-biofortified bean intervention affect work efficiency.MethodsA total of 125 iron-depleted (ferritin <20 μg/L) female Rwandan university students (18–26 y) were selected from a larger sample randomly assigned to consume iron-biofortified beans (Fe-Bean; 86.1 mg Fe/kg) or conventional beans (control: 50.6 mg Fe/kg) twice daily for 18 wk (average of 314 g beans consumed/d). Blood biomarkers of iron status (primary outcome) and physical work efficiency (secondary outcome) were measured before and after the intervention. Work performed was assessed during 5-min steady-state periods at 0-, 25-, and 40-W workloads using a mechanically braked cycle ergometer. Work efficiency was calculated at 25 W and 40 W as the work accomplished divided by the energy expended at that workload above that expended at 0 W. General linear models were used to evaluate the relation between changes in iron status biomarkers and work efficiency.ResultsThe Fe-Bean intervention had significant positive effects on hemoglobin, serum ferritin, and body iron stores but did not affect work efficiency. However, 18-wk change in hemoglobin was positively related to work efficiency at 40 W in the full sample (n = 119; estimate: 0.24 g/L; 95% CI: 0.01, 0.48 g/L; P = 0.044) and among women who were anemic (hemoglobin <120 g/L) at baseline (n = 43; estimate: 0.64 g/L; 95% CI: 0.05, 1.23 g/L; P = 0.036). Among women who were nonanemic at baseline, change in serum ferritin was positively related to change in work efficiency at 40 W (n = 60; estimate: 0.50 μg/L; 95% CI: 0.06, 0.95 μg/L; P = 0.027).ConclusionsIncreasing iron status during an iron-biofortified bean feeding trial improves work efficiency in iron-depleted, sedentary women. This trial was registered at clinicaltrials.gov as NCT01594359.

Highlights

Iron deficiency is one of the most common micronutrient deficiencies worldwide, affecting women, children, and infants most severely
A subsample of 125 Rwandan women were selected from the larger study sample to complete the physical performance tests (Figure 1)
This study suggests that the consumption of iron-biofortified beans produces significant improvements in iron status and that these changes in iron status affected physical performance when exercising at moderate intensities

Summary

Introduction

Iron deficiency is one of the most common micronutrient deficiencies worldwide, affecting women, children, and infants most severely. Strategies to reduce the burden of nutritional iron deficiency include dietary diversification, supplementation, commercial food fortification, and biofortification Of these 4 strategies, biofortification has the potential to become a sustainable, inexpensive, and effective solution at the population level, in the rural poor who have little or no access to commercial fortification and supplementation interventions [4]. Objective: This study aimed to examine whether changes in iron status from an iron-biofortified bean intervention affect work efficiency. Results: The Fe-Bean intervention had significant positive effects on hemoglobin, serum ferritin, and body iron stores but did not affect work efficiency. Conclusions: Increasing iron status during an iron-biofortified bean feeding trial improves work efficiency in irondepleted, sedentary women. This trial was registered at clinicaltrials.gov as NCT01594359.

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