Association between dietary total antioxidant capacity and chronic obstructive pulmonary disease: findings from the national health and nutrition examination survey

Abstract

This study aimed to investigate the association between dietary total antioxidant capacity (TAC) and chronic obstructive pulmonary disease (COPD) using data from the National Health and Nutrition Examination Survey (NHANES). This cross-sectional study included participants aged ≥ 40 years from NHANES cycles 2001–2018. COPD was defined as a self-reported physician diagnosis. TAC was calculated from 24-hour dietary recall data and categorized into quartiles. Weighted multivariable logistic regression models were used adjusting for demographic, socioeconomic, behavioral, and clinical factors to assess the association between TAC quartiles and COPD. Restricted cubic spline (RCS) analysis was performed to explore the dose-response relationship, and subgroup analyses were conducted to evaluate effect modification. Inverse probability weighting and multiple imputation were used for sensitivity analyses. A total of 29,225 participants were included in the final analysis, of whom 2,829 (9.7%) had COPD. In the fully adjusted model (Model 3), higher TAC was associated with lower odds of COPD compared with the lowest quartile (Q1): Q2 (OR = 0.83, 95% CI: 0.66–1.02, P  = 0.084), Q3 (OR = 0.71, 95% CI: 0.57–0.88, P  = 0.003), and Q4 (OR = 0.78, 95% CI: 0.62–0.99, P  = 0.040). RCS analysis demonstrated a significant nonlinear inverse dose–response relationship between dietary TAC and COPD risk (P for overall = 0.005; P for nonlinearity = 0.024). No significant effect modification was observed across any of the examined subgroups (all P for interaction > 0.05). Sensitivity analyses using inverse probability weighting and multiple imputation confirmed the robustness of the results. Higher dietary antioxidant capacity is associated with lower COPD risk in a nonlinear manner independent of smoking intensity, warranting further longitudinal research to confirm these findings. Not applicable.