A systematic review approach
The knowledge synthesis is based on a systematic review of relevant scientific literature in three life phases: 1) early life (prenatal and childhood), 2) adolescence (12 -25 years) and 3) adulthood (> 25 years). In childhood the focus was on dietary patterns and nutrients (fatty acids, vitamins and minerals) in relation to ADHD, autism spectrum disorders and depressive disorders. In adolescence and adulthood the focus was on dietary patterns and nutrients in relation to depressive disorders, anxiety disorders and psychotic disorders. Studies that examined the role of dietary patterns/nutrients in the prevention as well as in the treatment of the selected mental disorders were included. In addition to the review of the scientific literature, Dutch guidelines and treatment protocols for the selected mental disorders were reviewed to identify whether these contain suggestions for dietary advice. Furthermore, application of dietary advice in mental health practice was explored.
Healthy dietary patterns and omega-3 fatty acids
The results of the systematic literature review showed that healthy dietary patterns are associated with a lower risk for depressive symptoms and depression among adults. Among children and adolescents there is a lack of good quality studies on these associations. Omega-3 fatty acid supplements can have a beneficial effect in the treatment of depressive disorders among adults as an adjunct to treatment with anti-depressants. Omega-3 supplementation can also be effective in reducing ADHD-symptoms in children with ADHD.
The knowledge synthesis also showed that there are many gaps in the scientific knowledge for all three life phases. This indicates that further research on the role of dietary patterns/nutrients in the prevention and treatment of mental disorders is urgently needed. Recommendations for further research are provided in the report.