BACKGROUND

Given the changes in global environmental conditions and dietary patterns, understanding the potential impact of dietary factors on the risk of depression is crucial. The Planetary Health Diet Index (PHDI) is a dietary scoring system that integrates human health and environmental sustainability. This study aims to evaluate the association between the PHDI, the risk of depression, and mortality.

METHODS

Data from the National Health and Nutrition Examination Survey 2005-2018. Depression was assessed using Patient Health Questionnaire-9 (PHQ-9), with a score ≥ 10 indicating depression. PHDI calculated from 14 self-reported dietary groups, ranges from 0 to 140. Multivariable weight logistic and linear regression explored the association of PHDI with depression and total PHQ-9 score. Cox proportional hazards regression examined PHDI associations with mortality. Additional analyses included restricted cubic spline (RCS), threshold analyses, subgroup analyses, and multiple imputation.

RESULTS

Adjusting for confounding variables, each 10-point increase in PHDI was associated with an 11% lower risk of depression (OR = 0.89, 95% CI = 0.84, 0.94), 0.13 score of total PHQ (β=-0.13, 95% CI=-0.18, -0.08), and 17% of all-cause mortality (HR = 0.83, 95% CI = 0.73, 0.95). RCS indicated an inverse L-shaped association between PHDI and depression, and threshold effects analyses showed that the above associations were more significant in those with PHDI ≥ 76.01.

CONCLUSIONS

Adherence to the PHDI dietary pattern is associated with a reduced risk of both depression and all-cause mortality. PHDI may provide dietary guidance for the early prevention and intervention of depression.