title: Provitamin A Carotenoid-Biofortified Maize Consumption Increases Pupillary Responsiveness among Zambian Children in a Randomized Controlled Trial.
abstract: BACKGROUND
  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.
  
  
  OBJECTIVE
  We tested the impact of provitamin A carotenoid-biofortified maize consumption (∼15 μg β-carotene/g) on dark adaptation in Zambian children.
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors: Center for Human Nutrition, Department of International Health, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD; apalme17@jhu.edu.
authors: Amanda C
authors: http://orcid.org/0000-0002-3212-955X
authors: AC
authors: Palmer
authors: Center for Human Nutrition, Department of International Health, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD.
authors: Katherine
authors: K
authors: Healy
authors: Center for Human Nutrition, Department of International Health, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD.
authors: Maxwell A
authors: MA
authors: Barffour
authors: National Food and Nutrition Commission, Lusaka, Zambia; and.
authors: Ward
authors: W
authors: Siamusantu
authors: Tropical Diseases Research Centre, Ndola, Zambia.
authors: Justin
authors: J
authors: Chileshe
authors: Center for Human Nutrition, Department of International Health, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD.
authors: Kerry J
authors: KJ
authors: Schulze
authors: Center for Human Nutrition, Department of International Health, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD.
authors: Keith P
authors: http://orcid.org/0000-0001-9458-362X
authors: KP
authors: West
authors: Center for Human Nutrition, Department of International Health, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD.
authors: Alain B
authors: http://orcid.org/0000-0003-2502-7819
authors: AB
authors: Labrique
mesh_terms: D002648:Child; D002675:Child, Preschool; D004032:Diet; D005260:Female; D005527:Food, Fortified; D006801:Humans; D008297:Male; D062407:Meals; D009752:Nutritional Status; D000072664:Provitamins; D012025:Reflex, Pupillary; D014801:Vitamin A; D014802:Vitamin A Deficiency / Q000178:diet therapy* / Q000453:epidemiology; D015024:Zambia / Q000453:epidemiology; D003313:Zea mays; D019207:beta Carotene / Q000008:administration & dosage* / Q000494:pharmacology
chemical_list: D000072664:Provitamins; D019207:beta Carotene; D014801:Vitamin A
keywords: biofortification; dark adaptation; night blindness; pupillometry; vitamin A deficiency