Palmer Amanda C, Healy Katherine, Barffour Maxwell A, Siamusantu Ward, Chileshe Justin, Schulze Kerry J, West Keith P, Labrique Alain B
Center for Human Nutrition, Department of International Health, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD;
Center for Human Nutrition, Department of International Health, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD.
J Nutr. 2016 Dec;146(12):2551-2558. doi: 10.3945/jn.116.239202. Epub 2016 Oct 19.
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/m) 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/m), 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.
暗适应受损是维生素A缺乏的早期功能指标，定期摄入富含维生素A原类胡萝卜素的食物可能预防这种情况。
我们测试了食用富含维生素A原类胡萝卜素的生物强化玉米（约15μgβ-胡萝卜素/克）对赞比亚儿童暗适应的影响。
我们在赞比亚姆库希区对1024名4至8岁儿童进行了整群随机试验，比较了生物强化橙色玉米（OM）与白色玉米（WM）的常规食用情况（每日2餐，每周6天，共6个月）。主要结果是血清视黄醇反应。在一个随机样本（n = 542）中，我们使用数字瞳孔计测试了在暗适应状态下干预前后对分级光刺激（-2.9至0.1 log cd/m²）的反应。
在基线时，11.7%的儿童血清视黄醇<0.7μmol/L，14.4%的儿童暗适应受损（瞳孔阈值≥ -1.11 log cd/m²），2.3%的儿童患有夜盲症。OM组在基线时对光刺激的平均±标准差瞳孔反应性（16.1%±6.6%）比WM组（18.1%±6.4%）差（P = 0.02），但在随访时无差异（OM：17.6%±6.5%；WM：18.3%±6.5%）。在基线时血清视黄醇<1.05μmol/L的儿童中，OM组的瞳孔反应性改善程度（2.2%；95%CI：0.1%，4.3%）大于WM组（0.2%；95%CI：-1.1%，1.5%；P = 0.01），但基线状态充足的儿童之间无差异。我们发现治疗对瞳孔阈值或夜盲症没有影响。
定期食用富含维生素A原类胡萝卜素的生物强化玉米可提高维生素A边缘或缺乏状态儿童的瞳孔反应性，为食用这种生物强化作物的功能益处提供了证据。该试验在clinicaltrials.gov上注册为NCT01695148。
