Omnivore, vegan and vegetarian diet quality associations with depressive symptoms: A comparative cross-sectional analysis of the Australian Longitudinal Study on Women's Health

Background: Depressive symptoms are experienced by >350 million people globally. Research suggests that a diet rich in plant foods could be protective against depressive symptoms, but vegans and vegetarians who eat a predominant plant-based diet are known to have higher depressive symptoms than omnivores. Methods: This study aims to explore a secondary analysis of the association between diet quality and depressive symptoms in women born between 1973 and 1978 who follow vegan, vegetarian, and omnivore diets from the Australian Longitudinal Study of Women's Health at baseline (1996) and at three time points (2000, 2003 and 2009). Results: After controlling for covarying factors, there was a significant association between diet quality and depressive symptoms in both the plant-based and omnivore groups at both time points F(9, 4851) = 106.90, p < .001. There was no significant difference between diet quality and depressive symptoms between diet type. Conclusions: Despite diet type (plant-based or omnivore), adhering to a high-quality diet may decrease depressive symptoms and a low-quality diet may increase depressive symptoms in Australian women. Limitations: Caution should be exercised when interpreting these results due to the small sample sizes and small resulting coefficients, there is uncertainty that coefficients this small can be associated with any meaningful change in an individual being treated for depressive symptoms in a clinical setting.