School of Public Health, College of Medicine and Health Sciences, Arba Minch University, Arba Minch, Ethiopia; Department of Public Health and Primary Care, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium.
Department of Translational Physiology, Infectiology and Public Health, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium.
Am J Clin Nutr. 2024 Feb;119(2):470-484. doi: 10.1016/j.ajcnut.2023.11.005. Epub 2023 Nov 11.
Iron is an essential mineral whose deficiency results in cognitive alteration, impaired emotional behaviors, and altered myelination and neurotransmission. In animal models, it has been shown that vitamin A (VA) could affect cognition.
The study aimed to evaluate the effectiveness of intermittent iron and VA supplementation on cognitive development of schoolchildren, and to assess the interaction between these supplementations.
Considering a 2 × 2 factorial design, 504 children were randomly assigned to 1 of the 4 arms: placebo VA and placebo iron supplement; high-dose vitamin VA and placebo iron supplement; iron supplement and placebo VA; and iron and high-dose vitamin VA supplements. Cognitive development was assessed using Raven's Coloured Progressive Matrices, digit span, Tower of London, and visual search tasks.
The mean [± standard deviation (SD)] age of the enrolled children was 9.6 (±1.6) y. One-fifth of the children had iron deficiency or anemia, whereas 2.9%, 3.9%, and 12.1% of children had low iron stores, iron deficiency anemia, and VA deficiency, respectively. Intermittent iron supplementation did not result in any significant improvement of children's cognitive development and had a negative effect on the performance index of the visual search task compared with placebo (-0.17 SD, 95% confidence interval: -0.32, -0.02). Effects were evident among children with stunting, thinness, or children coming from understimulating home environments. High-dose VA supplementation resulted in a significant improvement of digit span z-score with a mean difference of 0.30 SD (95% confidence interval: 0.14, 0.46) compared with placebo VA. VA had a more beneficial impact for girls, children infected with helminths, and those from food secure households.
In a population where the prevalence of iron deficiency is low, intermittent iron supplementation did not have any or negative effect on the child's cognitive development outcomes. Conversely, VA supplementation improved the child's working memory.
The study is registered at clinicaltrials.gov as NCT04137354 (https://clinicaltrials.gov/study/NCT04137354).
铁是一种必需的矿物质，其缺乏会导致认知改变、情绪行为受损以及髓鞘形成和神经传递改变。在动物模型中，已经表明维生素 A（VA）会影响认知。
本研究旨在评估间歇性铁和 VA 补充对学龄儿童认知发育的有效性，并评估这些补充剂之间的相互作用。
考虑到 2×2 析因设计，将 504 名儿童随机分配到 4 个组中的 1 个：安慰剂 VA 和安慰剂铁补充剂；高剂量维生素 VA 和安慰剂铁补充剂；铁补充剂和安慰剂 VA；铁和高剂量维生素 VA 补充剂。使用 Raven 彩色渐进矩阵、数字跨度、伦敦塔和视觉搜索任务评估认知发育。
入组儿童的平均（±标准偏差（SD））年龄为 9.6（±1.6）岁。五分之一的儿童有铁缺乏或贫血，而 2.9%、3.9%和 12.1%的儿童分别有铁储存不足、缺铁性贫血和 VA 缺乏。间歇性铁补充对儿童的认知发育没有任何显著改善，与安慰剂相比，对视觉搜索任务的表现指数有负面影响（-0.17 SD，95%置信区间：-0.32，-0.02）。这种影响在发育迟缓、消瘦或来自刺激不足家庭环境的儿童中更为明显。高剂量 VA 补充可显著提高数字跨度 z 分数，平均差异为 0.30 SD（95%置信区间：0.14，0.46），与安慰剂 VA 相比。VA 对女孩、感染寄生虫的儿童和来自粮食安全家庭的儿童有更有益的影响。
在铁缺乏症患病率较低的人群中，间歇性铁补充对儿童的认知发育结果没有任何影响或产生负面影响。相反，VA 补充改善了儿童的工作记忆。
该研究在 clinicaltrials.gov 上注册为 NCT04137354（https://clinicaltrials.gov/study/NCT04137354）。
