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UBC Theses and Dissertations

The association between diet and mental health and wellbeing in young adults within a biopsychosocial framework and a planetary health rationale Rossa-Roccor, Verena


Background: Previous research has shown that predominantly plant-based diets can co-benefit human health and the health of the planet. However, studies on their association with mental health are scarce even though mental health disorders contribute substantially to the global burden of disease. This study utilized a biopsychosocial frame to assess this association among undergraduate students as this population is highly vulnerable to mental disorders and simultaneously most likely to adopt a plant-based diet. Methods: Cross-sectional survey data were collected that included assessments of depression (PHQ-9), anxiety (GAD-7), and quality of life. Diet was measured through a posteriori self-reported dietary patterns as well as through self-identification with a diet preference category (such as pescatarian, vegetarian, or vegan). Multiple regression analysis was used to test whether plant-based diet preferences or diet patterns were associated with mental health outcomes, controlling for age, gender, ethnicity, sleep, physical activity, body image, stress, stressful life events, and social support. Data were further explored to uncover trends among and characteristics of those following a plant-based diet. Findings: In this sample (n=339), the majority of students (87.4%, n=298) indicated that they had good to excellent quality of life, while 20.4% (n=69) screened positive for moderately severe or severe depression and 32.4% (n=110) screened positive for moderate or severe anxiety (generally indicating necessity of a clinical intervention). Three dominant dietary patterns were found (plant-based, animal-based, and processed foods); 28.1% (n=95) of participants self-identified as following a predominantly plant-based diet. After controlling for covariables, most notably social support, we found a significant association between the processed food diet pattern and depression (z-score β=.21, p≤.001; adj. R²=.39) and anxiety (z-score β=.14; p≤.001; adj. R²=.32) while no association emerged between diet preference categories and mental wellbeing. Conclusions: This study showed that diet intake rather than preference category should be considered when examining relationships with mental health outcomes. It further pointed at the importance of conceptualizing diet as a health behaviour that is embedded in a multidimensional biopsychosocial framework and an integrated model for future inquiry in this field was proposed.

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