Herring and mackerel are good sources of fatty acids EPA and DHA, proteins as well as vitamin D and iodine. Marine omega-3 fatty acids and iodine is associated with positive effects on cognitive functions. In observational studies, positive correlation between seafood intake and cognitive function has been observed, but results from randomized intervention trials with single components such as omega-3 capsules show divergent results. Seafood contains several nutrients that may explain a positive effect, but so far not implemented intervention studies with seafood on children and youth has been conducted. In this study we tested in an unblinded, randomized intervention study if consumption of herring and mackerel improved cognitive function in children aged 4-6 years old. In the study 232 children were randomly divided into two groups where one group receives meals three times a week containing oily fish, while the other group receiving meals containing meat. Eating experiment took place over a period of four months. At the start and end of the study, participants underwent cognitive tests and took biological samples. They also answered a questionnaire on diet, physical activity, sleep and mental health.
The main objective of this study was to investigate whether regular consumption of herring / mackerel or meat improves learning ability of kindergarten children.
The secondary objectives of this study was to investigate whether regular consumption of herring / mackerel or meat improves nutritional status of fatty acids EPA and DHA, vitamin D and iodine.