Currently, there is considerable interest in the possibility that dietary supplementation with fatty acids, mostly omega-3 fatty acids, will have potential benefits for brain development. Epidemiological and clinical studies support the idea that relative disappearance of omega-3 diet from the diet in developed countries has been linked with increases in both physical and mental disorders. Omega-3 deficiency may lead to cognitive impairment, motor dysfunction and visual acuity problems. It is further known that families with lower socioeconomic status may have poorer diet and, consequently, may not realize their full potential regarding their cognitive abilities. The aim of this project is to evaluate effectiveness of a diet intervention rich in omega-3 acid in healthy children 9-to-12 years old from less well-off families.