Association between dietary inflammatory index and depression in individuals with cardiovascular-kidney-metabolic syndrome stage 0–3: a cross-sectional study

Cardiovascular-Kidney-Metabolic (CKM) syndrome is a newly recognized condition characterized by systemic inflammation, a process also implicated in depression. The Dietary Inflammatory Index (DII) quantifies the inflammatory potential of diet, yet its association with depression among individuals with CKM syndrome remains underexplored. Utilizing data from 11,847 adults with CKM syndrome stages 0–3 enrolled in seven NHANES cycles (2005–2018), we examined the relationship between DII and depression. The DII was computed using 24-hour dietary recall data. Weighted logistic regression and restricted cubic spline (RCS) analyses were applied to evaluate linear and nonlinear associations. Subgroup and sensitivity analyses were also conducted to assess consistency and robustness. Elevated DII values were consistently associated with a greater likelihood of depression across all models. Participants in the highest DII quartile (Q4) exhibited significantly higher odds of depression than those in the lowest quartile (Q1). RCS models revealed a positive, nonlinear dose–response relationship. Additionally, a significant interaction was observed between DII and diabetes mellitus status. A pro-inflammatory dietary profile, reflected by higher DII scores, is positively associated with depression among individuals with CKM stages 0–3. These findings highlight the potential benefits of adopting anti-inflammatory dietary interventions to mitigate depression risk in this population.