Dietary patterns and depressive symptoms across different countries and ethnicities living in Europe

Depression is a common mental disorder that is associated with increased mortality and morbidity rates and reduced quality of life. Furthermore, it has a multi-causal pathogenesis with elevated inflammation levels and body mass index (BMI) being mostly investigated. Studies suggest a robust association between obesity and higher depression risk, with chronic inflammation being one of the most important underlying mechanisms. The overall aim of this thesis is to identify dietary patterns that may be related to depressive symptoms and test these associations in different populations, including ethnic minorities, living in Europe. Furthermore, this thesis explores some potential underlying mechanisms of depressive symptoms that may be influenced by diet. This thesis provides more insight into dietary patterns that are closely related to depressive symptoms in Italian older adults, in middle-aged UK residents and in a multi-ethnic population consisting of Dutch, South-Asian Surinamese, African Surinamese, Turkish and Moroccan ethnic groups. Due to the variety in the abovementioned characteristics, we were able to broadly examine and compare the diet-depressive symptoms relationship. From the studies described in this thesis we can draw the following conclusions: 1. We found evidence for the relationship between a ‘healthy’ dietary pattern that was high in vegetables, olive oil, grains, fruit, fish, legumes, dairy products and moderate in red meat and lower depressive symptoms for the whole population in Italian older adults and in a multi-ethnic population living in the Netherlands. 2. No consistent evidence was observed for the relationship between ‘unhealthy’ dietary patterns and depressive symptoms across countries and ethnic groups. 3. We found no evidence for BMI and inflammation to be underlying mechanisms explaining the diet-depressive symptoms relationship