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Provitamin A Carotenoid–Biofortified Maize Consumption Increases Pupillary Responsiveness among Zambian Children in a Randomized Controlled Trial

2016; Elsevier BV; Volume: 146; Issue: 12 Linguagem: Inglês

10.3945/jn.116.239202

1541-6100

Amanda Palmer, Katherine Healy, Maxwell A. Barffour, Ward Siamusantu, Justin Chileshe, Kerry Schulze, Keith P. West, Alain Labrique,

Retinal Development and Disorders

Impaired dark adaptation is an early functional indicator of vitamin A deficiency that may be prevented by regular dietary intake of foods containing provitamin A carotenoids.We tested the impact of provitamin A carotenoid-biofortified maize consumption (∼15 μg β-carotene/g) on dark adaptation in Zambian children.We used a cluster-randomized trial of children aged 4-8 y (n = 1024) in Mkushi District, Zambia, and compared the regular consumption (2 meals/d, 6 d/wk for 6 mo) of biofortified orange maize (OM) to white maize (WM). The primary outcome was the serum retinol response. In a random sample (n = 542), we used a digital pupillometer to test pre- and postintervention responses to graded light stimuli (-2.9 to 0.1 log cd/m2) in a dark-adapted state.At baseline, 11.7% of the children had serum retinol <0.7 μmol/L, 14.4% had impaired dark adaptation (pupillary threshold ≥ -1.11 log cd/m2), and 2.3% had night blindness. The mean ± SD pupillary responsiveness to light stimuli was poorer at baseline in the OM group (16.1% ± 6.6%) than the WM group (18.1% ± 6.4%) (P = 0.02) but did not differ at follow-up (OM: 17.6% ± 6.5%; WM: 18.3% ± 6.5%). Among children with serum retinol <1.05 μmol/L at baseline, there was greater improvement in pupillary responsiveness in the OM group (2.2%; 95% CI: 0.1%, 4.3%) than the WM group (0.2%; 95% CI: -1.1%, 1.5%; P = 0.01), but there were no differences in children with adequate baseline status. We found no effect of treatment on pupillary threshold or night blindness.The regular consumption of provitamin A carotenoid-biofortified maize increased pupillary responsiveness among children with marginal or deficient vitamin A status, providing evidence of a functional benefit to consuming this biofortified crop. This trial was registered at clinicaltrials.gov as NCT01695148.