The bidirectional association between highly processed food consumption and major depressive disorder among adults in Spain

Highly processed food (HPF) consumption has been linked with an increased risk of depression. However, the role of major depressive disorder (MDD) as a potential risk factor for higher HPF consumption remains largely unexplored. This study aims to examine the bidirectional association between HPF consumption and MDD. We analyzed cross-sectional data from a representative sample of 1,380 non-institutionalized adults from Spain surveyed in 2023-2024. HPF intake was assessed using the short-form Questionnaire of Highly Processed Food Consumption (sQ-HPF). MDD during the previous 12 months was assessed using the Composite International Diagnostic Interview (CIDI). Adjusted regression models were constructed to evaluate factors related to MDD and high HPF consumption. Compared to participants in the lowest HPF consumption tertile, those in the medium tertile showed a non-significant trend toward greater odds of 12-month MDD (OR = 2.64; 95% CI: 0.79-8.84; p = 0.115), while those in the highest tertile had significantly increased odds (OR = 8.03; 95% CI: 2.95-21.82; p < 0.001). In the reverse model, participants with 12-month MDD had 4.83 times greater odds of belonging to a higher HPF consumption tertile (OR = 4.83; 95% CI: 2.10-11.12; p < 0.001). Our findings suggest a bidirectional association between HPF consumption and MDD. Individuals with higher HPF intake are more likely to experience MDD, and those with MDD tend to report greater HPF consumption. These results underscore the need for integrated prevention strategies addressing both nutritional behavior and mental health.