Abstract:
Background The diet quality of young people has deteriorated significantly over recent decades. Poor diet quality has previously been implicated in poor physical health outcomes, including obesity, heart disease, and diabetes. However, more recently, there has been an interest in the relationship between diet quality and mental health, especially depression. The alarmingly high prevalence of depression in adolescent populations presents a threat to the emotional, physical, and social wellbeing of young people. Therefore, examining the relationship between diet, a modifiable lifestyle factor, and depression may have implications for improving the mental health of young people. Aims and Objectives This study explored the relationship between diet quality and self-reported mental health in an ethnically diverse adolescent population. Specifically, two objectives were examined: - Cross-sectional analyses to determine if diet quality is associated with mental health; and - Prospective analyses to determine if diet quality predicts mental health over time. Method Data for the study was derived from baseline and follow-up measurements of the New Zealand arm of the Pacific Obesity Prevention in Communities (OPIC) study. Six high schools in the South Auckland region of New Zealand participated in the OPIC study. All students enrolled in years 9-13 of participating schools were eligible to take part. Data was available for 4249 students at baseline; 679 students also had one-year follow-up data. Responses from self-report dietary questionnaires were used to assess diet quality; healthy eating and unhealthy eating were assessed as two separate scales measuring various eating behaviours. Mental health was assessed by the emotional subscale of the PedsQL instrument. Results A significant cross-sectional relationship was identified between diet quality and mental health. Eating a healthy diet was associated with fewer depressive symptoms; eating an unhealthy diet was associated with more depressive symptoms. These relationships remained significant after controlling for age, ethnicity and gender. No significant relationships were observed between diet quality at baseline and mental health scores at one-year follow-up. Conclusions These findings suggest that diet quality is associated with mental health in adolescents; however, the relationship between the variables over time is ambiguous and requires further exploration.