BACKGROUND Intervention studies suggest an influence of breakfast dietary glycemic index (GI) on children's cognition. The Cognition Intervention Study Dortmund-GI-I study examined whether lunch dietary GI might have short-term effects on selected cognitive parameters. METHODS A randomized crossover study was performed at a comprehensive school on 2 test days. One hundred and eighty-nine participants (5th and 6th grade) were randomly assigned to one of the two sequences, medium-high GI (m-hGI) or high-medium GI (h-mGI), following block randomization. In the first period, one group received a dish containing hGI rice (GI: 86) ad libitum, the other mGI rice (GI: 62)-1 week later, in the second period, vice versa. Tonic alertness, task switching, and working memory updating were tested with a computerized test battery 45 min after beginning of lunch break. Treatment effects were estimated using the t test for normally distributed data or the Wilcoxon rank-sum test for non-normally distributed data. RESULTS The crossover approach revealed no effects of lunch dietary GI on the tested cognitive parameters in the early afternoon. However, we determined carryover effects for two parameters, and therefore analyzed only data of the first period. The reaction time of the two-back task (working memory updating) was faster (p = 0.001) and the count of commission errors in the alertness task was lower (p = 0.04) in the hGI group. CONCLUSION No evidence of short-term effects of lunch dietary GI on cognition of schoolchildren was found. Potential positive effects on single parameters of working memory updating and tonic alertness favoring hGI rice need to be verified.

中文翻译：

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在一项随机交叉研究中，午餐时摄入的不同血糖指数 (GI) 的碳水化合物对儿童认知功能的短期影响。

背景 干预研究表明早餐膳食血糖指数 (GI) 对儿童认知有影响。认知干预研究 Dortmund-GI-I 研究检查了午餐饮食 GI 是否可能对选定的认知参数产生短期影响。方法 在一所综合性学校进行为期 2 天的随机交叉研究。189 名参与者（5 年级和 6 年级）在分组随机化后被随机分配到两个序列之一，中高 GI (m-hGI) 或高中 GI (h-mGI)。在第一阶段，一组随意接受含有 hGI 大米（GI：86）的菜，另一组 mGI 大米（GI：62）-1 周后，在第二阶段，反之亦然。滋补警觉，任务切换，午休开始后 45 分钟，使用计算机测试电池测试工作记忆更新。使用正态分布数据的 t 检验或非正态分布数据的 Wilcoxon 秩和检验估计治疗效果。结果 交叉方法显示午餐饮食 GI 对下午早些时候测试的认知参数没有影响。然而，我们确定了两个参数的结转效应，因此只分析了第一阶段的数据。在 hGI 组中，两回任务（工作记忆更新）的反应时间更快（p = 0.001）并且警觉任务中的委托错误计数较低（p = 0.04）。结论 没有发现午餐膳食 GI 对学童认知的短期影响的证据。