Background: Observational studies suggest that dietary patterns may impact mental health outcomes, however biologically plausible pathways are yet to be tested. In this study we aimed to elucidate pathways between dietary patterns, adiposity, inflammation and mental health including depression longitudinally in a population-based cohort of adolescents.
Methods: Data were provided from 843 adolescents participating in the Western Australian Pregnancy Cohort (Raine) Study at 14 and 17 years of age. Structural equation modelling was conducted to test hypothesised models relating dietary patterns, energy intake and adiposity (body mass index) at 14 years to adiposity and the pro-inflammatory adipokine (leptin), inflammation (high sensitivity C-reactive protein – hs-CRP) at 17 years, depressive symptoms (Beck Depression Inventory) and internalising and externalising problem behaviours (Child Behaviour Check List Youth Self- Report) at 17 years.
Results: The tested models provided a good fit to the data. A ‘Western’ dietary pattern (high intake of red meat, takeaway, refined foods and confectionary) at 14 years was independently associated with higher energy intake and BMI at 14 years and BMI and inflammation at 17 years. A ‘Healthy’ dietary pattern (high in fruit, vegetables, fish, whole-grains) was inversely correlated with BMI and inflammation at 17 years. Higher BMI at 14 was correlated with higher BMI, higher leptin and hs-CRP, depressive symptoms and mental health problems at 17 years.
Conclusions: A ‘Western’ dietary pattern appears to increase the risk of mental health problems including depression in adolescents through biologically plausible pathways of adiposity and inflammation. A ‘Healthy’ dietary pattern is protective in these pathways. Further longitudinal modelling into young adulthood is indicated to confirm these complex associations.