In May this year, we published a fascinating Paper of the Month blog post on Nordic school meals' influence on children’s school performance. The following Q&A is with the lead author of that paper, Louise Bergmann Sørensen, from the Department of Nutrition and Exercise, University of Copenhagen.
Q. Your study chose to focus on the impact of diet in well-nourished children. Would you expect a different outcome if the study was carried out in under-nourished children?
Yes, we would expect a greater effect in under-nourished children, since the intervention meals would constitute a greater part of their diet and there would be a larger difference between dietary intake in the control and intervention period.
Q. There has been much research into the benefits of children eating a nutritious breakfast. Would you expect different results in the attention, processing speed and maths tests if the study included breakfast?
School breakfast programmes and observational studies indicate that breakfast frequency and quality positive effects on school performance. If the study had included a nutritious breakfast, it is plausible that the impact on dietary intake would have been larger and thereby we could expect greater cognitive effects.
It is also possible that we would see different effects if the study had included breakfast. It is difficult to predict the effects on specific tests, but school breakfast programmes seem to have effects classroom behaviour, school grades and academic performance, especially in mathematics. Moreover, studies investigating breakfast vs. no breakfast indicate acute beneficial effects on memory and attention in particular. Finally, evidence suggests that carbohydrate quality of the breakfast meal might influence memory, vigilance and processing speed.
Q. The Nordic diet is often considered to be generally healthy and has recently been publicised as the diet pattern to follow for good health (in the UK at least). Were the children’s diets accessed prior to the study therefore determining that your intervention provided an improved diet?
Yes, prior to the study we performed a dietary survey focusing on intake during school hours in Danish 8- to 12-year-old children. On average the survey showed that the midmorning, lunch and afternoon meals contributed with 40-44 % of daily energy intake and that there was room for improvements in these meals. In particular, the meals contained too much sugar, fat and salt, and too little fish, vegetables, fruit and fibre. Additionally, the survey showed socioeconomic inequality in dietary intake and that about 12% of children did not eat any lunch. Thus, we expected the intervention meals to contribute toward a healthier dietary intake.
Q. As you state in your introduction, it is widely agreed that a healthy, balanced diet should improve cognitive performance. Do you have any proposed explanations for your results?
In whole meal intervention studies you cannot to determine exactly which dietary aspects that explain the results. However, the increased fish intake during the intervention could point toward that long chained n-3 fatty acids might explain some of the effect. This aspect will be explored in a separate paper.
Q. Are you planning to investigate the effects of healthy, balanced meals on cognitive performance further?
The lack of evidence in this area means that there is a long way to go before we can conclude on the cognitive significance of healthy meals in school and in general. Currently, we are applying for funding to study the effects of fatty fish on cognition.