The moderating role of workforce participation on the association between inflammatory diet and depression among US adults: findings from NHANES 2005-2018

Background Depression in the workforce is a highly prevalent and prominent public health problem with pro-inflammatory diet. We aimed to assess the association between inflammatory diet and depression, then to further examine the moderating role of workforce participation on the association of inflammatory diet with depression among US adults aged 20 years or above. Methods Data from the National Health and Nutrition Examination Survey (NHANES) 2005–2018 was used. Binary logistic regression and moderating effect analysis were conducted to explore the associations between inflammatory diet, workforce participation, and depression. Restricted cubic spline (RCS) were employed to evaluate the dose–response association of dietary inflammatory index (DII) and hours worked per week with depression at different levels. Results A total of 23,163 participants were enrolled with a depression prevalence of 7.4%. Both pro-inflammatory diet and not working were risk factors for depression. After adjusting for covariates, adults with pro-inflammatory diet (DII ≥ 0) were more likely to suffer from depression (OR = 1.30; 95%CI: 1.10–1.55). Workforce participation moderated the association between inflammatory diet and depression, especially moderating effect of not working and regular daytime working on the association of DII with depressive tendency was 0.12 and − 0.06. The protective effect of anti-inflammatory diet against depression was only found during the working period of 25 to 45 hours peer week. These effects were consistent across the analyses of subgroup and sensitivity. Conclusions Not working may exacerbate the increase of pro-inflammatory diet to depression risk. Modest regular daytime working (25–45 hours per week) with anti-inflammatory diet may better in reducing depression risk.