Background/Objective: Depression, affecting approximately 5% of adults globally, arises from complex interactions involving genetic, environmental, behavioral, socioeconomic, and physical health factors, requiring multifaceted approaches for prevention and treatment. Emerging evidence suggests that dietary habits, particularly the consumption of fermented foods, may influence mental health via the microbiota-gut-brain axis; probiotics present in fermented foods potentially modulate gut microbiota composition, affecting neurotransmitter production and inflammatory pathways associated with depression. This study aims to evaluate the association between fermented food consumption and depression risk in a nationally representative sample of U.S. adults.

Methods: Adults (≥18 years) from NHANES who completed the Patient Health Questionnaire-9 (PHQ-9) depression screening at NHANES’s Mobile Examination Center (MEC) were included, excluding those with incomplete or missing responses. Fermented food consumption was assessed through two 24-hour dietary recalls administered by telephone within 3–7 days post-MEC visit. Self-reported food items were initially coded using the NHANES Food Code Description file and subsequently coded as fermented and non-fermented food items using an authoritative expert publication. Chi-square tests and binary logistic regression models estimated the association between depression and fermented food intake, while controlling for socio-demographic, behavioral, and health-related covariates.

Results: Among 5,323 U.S. adults, a majority were 60–69-year-olds (25.0%), female (54.7%), non-Hispanic white (61.4%), college graduate and beyond (37.8%), married/living with a partner (54.1%), consume fermented foods (40.7%) and had screened at risk for depression on PHQ9 (13.0%). A greater number of adults with depression consumed less fermented foods compared to adults without depression (42.3% vs. 33.6%; p=.001). Adults who do not consumed fermented foods were significantly more likely to screen high for clinical depression (AOR=1.43;95%CI:[1.13-1.82]) compared to adults who consumed fermented foods even after controlling for covariates.

Conclusion: Lower fermented food consumption was significantly associated with increased risk of depression among U.S. adults. These findings support the hypothesis that dietary practices, specifically incorporating fermented foods, may play a protective role in mental health, highlighting the potential for dietary interventions in depression prevention and management.