Effects of lunch on children's short-term cognitive functioning: a randomized crossover study.
Considering the large number of children worldwide attending all-day schools, information on the effects of lunch on short-term cognitive performance is of public health relevance. However, only adult studies investigated this issue yet. Therefore, this study examined the impact of skipping lunch vs having lunch on children's cognitive functioning in the early afternoon. Participants in this randomized crossover study with two groups were healthy 6th grade students of an all-day school in Gelsenkirchen, Germany. Group 1 skipped lunch on study day 1 and received an ad libitum lunch 1 week later on study day 2. The order for group 2 was vice versa. In the afternoon tonic alertness, visuospatial memory and selective attention were determined using a computerized test battery of the Vienna Test System. For continuous and discrete interval-scaled variables, treatment effect was estimated using the two sample t-test or the Wilcoxon rank-sum test, for discrete ordinal-scaled variables using generalized linear models. Data on 105 children (48% male; 12.6 ± 0.6 years) were analyzed. Except for tonic alertness there were no significant differences in cognitive functioning between the skipping lunch day and the having lunch day. The higher number of omission errors on the skipping lunch day lost significance when adjusting for multiple testing. In the first study on this topic lunch did not have relevant effects on children's cognitive functioning in the early afternoon. Future research needs to be done to figure out potential methodical and physiological explanations.