Adherence to a Vegetarian Diet is not Associated With Depression: Results From the National Health and Nutrition Examination Surveys

OBJECTIVE: Adherence to vegetarian diets has been associated with physical health benefits, whereas vegetarian mental health is less well documented. We sought to investigate whether adherence to a vegetarian diet was associated with depression in a nationally-representative sample of US adults. METHODS: We used population-based data from the US National Health and Nutrition Examination Surveys to examine said associations. Depression was assessed using the Patient Health Questionnaire (PHQ-9), vegetarian status was self-reported. Multivariate regression was used to measure the magnitude of associations, controlling for a range of covariables known to be associated with depressive symptoms. RESULTS: Our analysis included 9,584 individuals, of which 910 individuals had PHQ-9 scores suggestive of depression. Vegetarian diet was associated with reduced odds of PHQ-9 defined depression (odds ratio [OR]: 0.49 [95% confidence interval {CI}: 0.24–0.98], p=0.047) in a model adjusting for sex, age, ethnicity, income, and marital status. When adjusting for additional factors (educational level, smoking status, serum C-reactive protein, and body mass index) in a second model, the previously observed association was no longer significant (OR: 0.66 [CI: 0.34–1.26], p=0.203). CONCLUSION: Vegetarian diet was not associated with PHQ-9 defined depression in this nationally-representative sample of adults. Additional longitudinal examinations are warranted to evolve the understanding of the role of vegetarian diets in mental health.