Purpose: In this study, we aimed to examine the relationship between diet quality and depression in a prospective study of adolescents from varied ethnic and cultural backgrounds.
Design: In this prospective cohort study, data were collected at two time points (2001 and 2003) from nearly 3,000 adolescents, aged either 11-12 years or 13-14 years, participating in RELACHS, a study of ethnically diverse and socially deprived young people from East London in the UK. Diet quality was measured from dietary questionnaires, and mental health assessed using the Strengths and Difficulties Questionnaire (SDQ) and the Short Mood and Feelings Questionnaire (SMFQ).
Results: In cross-sectional analyses, we found evidence for an association between an unhealthy diet and mental health problems. Compared to those in the lowest quintile of Unhealthy diet score, those in the highest quintile were more than twice as likely to be symptomatic on the SDQ (OR 2.10, 95 %CI 1.38-3.20) after taking all identified confounders into account. There was also some evidence for a cross-sectional inverse association between a measure of healthy diet and mental health problems. A prospective relationship between the highest quintiles of both Healthy (OR 0.63, 95 %CI 0.38-1.05) and Unhealthy (OR 1.75, 95 %CI 1.00-3.06) diet scores and SDQ scores at follow-up was also evident, but was attenuated by final adjustments for confounders.
Conclusion: This study is concordant with previous observational studies in describing relationships between measures of diet quality and mental health problems in adolescents.