The impact of dietary antioxidant quality score on the relationship between smoking and chronic obstructive pulmonary disease in adults

Smoking has been confirmed to induce systemic inflammation and oxidative stress (OS) and is associated with higher odds of chronic obstructive pulmonary disease (COPD). Dietary antioxidants can reduce inflammation and OS. This study seeks to score the dietary antioxidant intake and then assess its impact on the association between smoking and COPD in adults. The data extracted from the 2007-2012 National Health and Nutrition Examination Survey database were used. The Dietary Antioxidant Quality Score (DAQS) was evaluated by the total intake of vitamins A, C and E, Se, Zn and Mg in the daily diet. Smoking was used as the exposure variable and COPD as the outcome variable. Weighted multivariable logistic regression was conducted to evaluate the associations of DAQS with smoking and COPD, as well as their joint effects on the odds of COPD. The relationships between dietary antioxidant quality score, smoking status and COPD were subsequently assessed. Subgroup analyses were performed to explore associations between relevant covariates and smoking and COPD across DAQS strata. Current smoking was found to be linked to COPD (OR = 4·06, 95 % CI = 3·14, 5·27) in comparison to never smoking. Among smokers, significant associations were observed in both the medium-quality DAQS group (OR = 3·48, 95 % CI: 2·34, 5·17) and the low-quality DAQS group (OR = 5·60, 95 % CI: 3·58, 8·76). In conclusion, high DAQS levels are inversely related to the odds of COPD in adult smokers. Our findings provide valuable insights for management strategies for COPD.