The brain is primarily developed in the third trimester of pregnancy, but continues maturing through the late twenties, especially the prefrontal cortex. Omega-3 long-chain polyunsaturated fatty acids (LCPUFA) are important structural components of neural cell membranes, influence membrane fluidity and signal transduction, and thus learning, cognition and behaviour. Levels of omega-3 LCPUFA have been found to be low in individuals with limitations in these complex brain functions. Previous studies suggested that such functions could be improved by increasing LCPUFA. The adolescent brain, however, has been largely neglected. This study investigates the effect of one-year daily omega-3 LCPUFA supplementation, in particular krill oil, in healthy 14-15 year old adolescents in lower general secondary education (MAVO/VMBO) on learning, cognition, and behaviour. The majority of the omega-3 PUFA in krill oil is incorporated into phospholipids, favouring tissue uptake of its omega-3 PUFA. In a double blind, randomised controlled trial, 300 adolescents preselected from a population of 700 adolescents with low omega-3 index (<5%) will receive daily omega-3 LCPUFA supplementation or matching placebo. The omega-3 LCPUFA dose will be adjusted individually to reach a target level of 8-11%. The effects on learning (academic achievement, objective cognitive performance), behaviour (mood, self-esteem, motivation, goal-orientation, absenteeism), and in a subsample cognitive processes, in particular perceptual processes measured by eye-tracking will be evaluated after 6, 12, and 24 months. This study will yield important insights in the effects of omega-3 LCPUFA supplementation, a safe intervention, on a large variety of complex brain functions.

Inclusion Criteria:

• Healthy adolescents aged 14-15 years.
• In lower general secondary education (MAVO/VMBO).

Exclusion Criteria:

• Suffering from hemophilia (blood clotting disorder).
• Allergic to (shell)fish.