Lunch in children and adolescents : meal pattern and relevance for the short-term cognitive functioning

摘要

Lunch is a meal that is eaten at midday and differs considerably between countries regarding meal type (cold vs. hot meal) and meal size (multicourse vs. snack meal). Considering the large number of schoolchildren attending all-day schools, information on their lunch pattern and on the acute effects of lunch on their cognitive functioning are of high public health relevance. Therefore, the objectives of this thesis were to describe and evaluate potential differences in lunchtime energy and food intake of adolescents (13-17 years) at their usual lunch location (school, home or elsewhere) and to examine the impact of skipping lunch vs. having lunch on schoolchildren’s (12.6 ± 0.6 years) short-term cognitive functioning.To consider lunch pattern, the existing data of the HEalthy Lifestyle in Europe by Nutrition in Adolescence Cross-Sectional Study (HELENA-CSS) were used, in particular lunchtime food intake data obtained from two self-administered, computerized 24-hour recalls (24HR) and data on usual lunch location. Food intake was compared to lunch of the Optimized Mixed Diet (OMD), a meal-based dietary guideline for children and adolescents. Data on the acute effects of lunch on schoolchildren’s cognitive functioning were collected in a randomised crossover study. Setting was an all-day school in Gelsenkirchen, Germany. Group 1 skipped lunch on study day 1 and received lunch ad libitum one week later on study day 2, while group 2 was treated vice versa. On both study days tonic alertness, visuospatial memory, and selective attention were tested in the early afternoon using a computerized test battery of the Vienna Test System (VTS).Even though the adolescents’ energy intake was comparable with the OMD, their food intake was suboptimal compared to the recommendation regardless of usual lunch location. Adolescents had more potatoes and less sweets at school, and more unsweetened drinks (water, coffee and tea) and vegetables at home when each compared with the other locations. Food intake of adolescents getting their lunch elsewhere was characterised by the smallest amounts of potatoes and the highest amounts of sweets. Except for tonic alertness there were no statistically significant differences in cognitive functioning between the skipping and the having lunch day. However, the higher number of omission errors on the skipping lunch day lost significance when adjusting for multiple testing.In conclusion, lunch on school days is improvable regardless of usual lunch location. To deduce and implement any cognition-related nutritional recommendations for schoolchildren, more research on the short-term effects of lunch on cognitive functioning is fundamental.