Methods: Fieldwork team will contact teenagers and families in collaboration with 20 high schools. Families will receive a basic guide on following a healthy diet in order to ensure implementation and adherence. Brain development outcomes will be measured at baseline and after the intervention. The use of computerized neuropsychological tests will provide the precision required to detect even subtle changes in brain development resulting from the nutritional intervention. Behavioral (socio-emotional) development will be assessed in order to cover a wider picture of brain development. Blood samples will be collected to measure n-3 PUFA levels before and after the intervention in a randomized subsample from both groups (control/ intervention). Linear regression models adjusted for baseline neuropsychological scores will be used to analyze the intervention effect.