Investigating associations between diet and depression at the population level over time: results from the National Health and Nutrition Examination Survey.

Depression contributes substantially to disease burden in the United States. Diet is a modifiable risk factor, yet surprisingly the population-level diet-depression association has never been comprehensively evaluated over time. We aimed to assess prevalence of suboptimal dietary intakes and depression, and the association between diet and depression over time using National Health and Nutrition Examination Survey (2005–2018) data. Complete-case logistic regression assessed associations between diet (following Global Burden of Disease definitions, plus ultra-processed food [UPF]; measured using 24-hour recalls) and odds of depression (defined as PHQ-9 ≥ 10). Depression prevalence (7.69%) was consistent from 2007–2018. Prevalence of suboptimal milk intake increased over time (p = 0.003), but suboptimal processed meat (p = 0.038), red meat (p = 0.022), nuts/seeds (p = 0.001), and polyunsaturated fat intake decreased (p < 0.001). Higher fiber intake was consistently associated with lower odds of depression from 2005–2018, while higher UPF intakes were associated with higher odds from 2007–2018. All other dietary risks were associated at various years but not consistently at each wave. Given previously observed causal relationships between diet and depression, improving population-level fiber intake and reducing UPF consumption may plausibly reduce depression burden in the United States. These results support the Global Burden of Disease Lifestyle And mental Disorders project (DERR2-10.2196/65576).