The aim is to examine the role of life styles, social background and socioeconomic factors on the mood-nutrition reciprocal relationships using samples from countries with different diets and different levels of mental health problems. For example, Mediterranean, Scandinavian and UK or US samples have been investigated in isolation but no study has carried out a comparison of social and dietary influences on mental health in different countries. Other factors which can be examined are changes in diet-mental health relationships across different age groups, gender and socio-economic status.

The research methodology will be largely based on secondary analyses of existing databases. In some cases the diet-mental health relationships have already been examined and the novel part will be the inclusion of social influences into the analyses. However, there are also extensive new samples which can provide new information on these topics. For example, in the UK the Biobank initiative has led to the collection of relevant data from 350,000 individuals. This database is potentially available (for a small fee) to the present project.