Abstract
BackgroundIntervention 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.MethodsA 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.ResultsThe 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.ConclusionNo 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.
Highlights
These authors contributed : Kathrin Jansen, Jana TempesThese authors jointly supervised this work: Thomas Lücke, Mathilde Kersting Bochum, GermanyChildren attending all-day schools are challenged to maintain cognitive performance until the afternoon
Statistical analyses revealed no significant differences between lunch based on medium or high glycemic index (GI) rice for most parameters of the selected cognitive outcomes (Table 2)
Eating lunch with high GI (hGI) rice resulted in shorter reaction time (RT) compared with lunch with medium GI (mGI) rice
Summary
These authors contributed : Kathrin Jansen, Jana TempesThese authors jointly supervised this work: Thomas Lücke, Mathilde Kersting Bochum, GermanyChildren attending all-day schools are challenged to maintain cognitive performance until the afternoon. Term positive effects on cognitive performance [2, 3], high consumption of carbohydrates leading to fast and high increases in postprandial blood glucose might restrain cognitive potentials [4]. The glycemic index (GI) ranks available carbohydrates provided by carbohydrate-rich foods by their effects on postprandial blood glucose concentrations. A repeated-measures study did not report effects on cognition by breakfasts differing in their dietary GI [11]. To the best of our knowledge, studies on lunch dietary GI and short-term cognitive effects in children are not available up to now. 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. Treatment effects were estimated using the t test for normally distributed data or the Wilcoxon rank-sum test for nonnormally distributed data
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