Impact of Provitamin a Biofortified Maize Flour Consumption on Dark Adaptation in Zambian Children.

Objectives: Approximately one third of children in developing countries are deficient in vitamin A (VA). Of these, 5.2 million are affected by night blindness—a severe impairment in dark adaptation. ProVA biofortified “orange” maize has been introduced in Africa as a potential intervention to address VA deficiency. We tested the impact of regular orange maize flour consumption on dark adaptation in preschool-aged children. Methods: This was a cluster-randomized trial of children aged 4-8 years (n=1,024; 50 clusters) in Mkushi, Zambia comparing orange maize to conventional white maize. A random subsample (n=542) was assessed pre- and post-intervention using a portable field dark adaptometer to record pupillary response to varying light stimuli (-2.9 to 0.1 c/m2). We measured pre- and post-stimuli pupil diameter using Tracker video analysis software and calculated the % change (i.e., “responsiveness”). Pupillary threshold was defined as the lowest stimulus causing a ≥20% reduction in pupil diameter. Results: At baseline, children assigned to orange maize were less responsive than those in the white group to all light stimuli. After the six-month intervention, pupillary responsiveness in the orange group improved across all stimuli. No consistent changes in responsiveness were observed in the white group. Pupillary threshold scores improved in 47% of orange group children versus 35% in the control arm. Improvements were more pronounced among children who consumed >75% of the maize meal provided, compared to those with lower compliance. Conclusions: Regular consumption of proVA biofortified maize flour improved dark adaptation in a marginally VA deficient population.

Malaria Exacerbates Inflammation-induced Bias in Ferritin and Soluble Transferrin Receptor Values.

Objectives: In the context of malaria and inflammation, the utility of ferritin and soluble transferring receptor (sTfR), as indicators of iron status may be compromised. In this study, we evaluated the effects of correcting for malaria and inflammation on the prevalence of iron deficiency (ID) as estimated by a) ferritin and b) sTfR. Methods: The analyses used baseline data from 1085 children, 4-8 y, who participated in a carotenoid biofortified maize flour trial in rural Zambia. For each biomarker, we compared the prevalence of ID with the prevalence corrected for a) CRP and AGP only; and b) CRP, AGP and concurrent malaria. Inflammation was defined as CRP>5mg/L and/or AGP>1g/L. Malaria was defined by microscopy. Children were first stratified into groups defined by inflammation and malaria status. Correction factors were then generated by dividing the group geometric means by that of the reference group (those free of both malaria and inflammation). Correction factors were applied to each individual concentration to generated corrected concentrations. Results: For ferritin, the unadjusted prevalence of ID (WHO age-specific cut-offs) increased from 7.3% to 9.5% (p<0.01) and 10.3 %( p<0.01), respectively, after correcting for CRP/AGP only, and CRP, AGP and concurrent malaria combined. For sTfR, the unadjusted ID prevalence (cutoff >8.3 mg/l) decreased from 28% to 21% (p<0.01) after correcting CRP/AGP only, and 19% (p<0.01) after correcting for CRP, AGP and concurrent malaria. Conclusions: Our findings highlight the need to account for both malaria and inflammation when interpreting ferritin and sTfr concentrations in malaria endemic regions.