The independent and joint relationships between dietary antioxidant intake with risk of chronic obstructive pulmonary disease and all-cause mortality: insights from NHANES

Abstract

Background: Numerous studies have indicated that a diet rich in antioxidants can prevent Chronic Obstructive Pulmonary Disease (COPD). However, the relationship between combined dietary antioxidant intake and the risk of COPD remains unclear. The Comprehensive Dietary Antioxidant Index (CDAI) is a composite score of various dietary antioxidants, including vitamins A, C, E, zinc, selenium, and carotenoids. In this study, we examined the independent and joint associations of CDAI with the risk of COPD and all-cause mortality.

Methods: The analysis was conducted using data from the National Health and Nutrition Examination Survey (NHANES) spanning from 2013 to 2018. Multivariable weighted logistic and Cox regression models were employed to evaluate the correlations of CDAI (including vitamins A, C, E, zinc, selenium, and carotenoids) with the risk of COPD and all-cause mortality. Restricted cubic spline models were used to examine potential non-linear relationships. Sensitivity and stratified analyses were conducted to assess the robustness of the results.

Results: In this study, compared to the lowest quartile, the highest quartile of CDAI levels was significantly negatively associated with the risk of COPD (Odds Ratio [OR]: 0.47; 95% Confidence Interval [CI]: 0.22-0.97), exhibiting a non-linear relationship. Additionally, vitamins A, C, E, zinc, selenium, and carotenoids were also negatively associated with the risk of COPD. Furthermore, dietary antioxidant zinc in the second quartile (Hazard Ratio [HR]: 0.25; 95% CI: 0.10-0.62) was negatively associated with the risk of all-cause mortality compared to the lowest quartile. Subgroup analysis results remained stable, and sensitivity analysis did not support the association between selenium and the risk of COPD, with no substantial changes in the remaining associations.

Conclusion: Higher CDAI is inversely associated with the risk of COPD, and appropriate intake of the dietary antioxidant zinc may reduce all-cause mortality in COPD patients.

Keywords: NHANES; chronic obstructive pulmonary disease; comprehensive dietary antioxidant index; oxidative stress; restricted cubic spline.

Figure 1

Flowchart for the selection of eligible participants. NHANES, National Health and Nutrition Examination Survey; CDAI, Composite Dietary Antioxidant Index; COPD, Chronic obstructive pulmonary disease.

Figure 2

Nomogram and the validation of its ROC curve, calibration plot, and DCA. (A) Nomogram: Utilized for COPD risk assessment. (B) ROC Curve: The area under the ROC curve was employed to assess the accuracy of the nomogram. (C) Calibration Plot: Represents the diagnostic nomogram’s calibration, with the ideal prediction shown by the diagonal 45-degree line. (D) DCA: Provides an analysis of the net benefit derived by adding true positives and subtracting false positives, illustrating the effectiveness of the diagnostic nomogram in clinical decision-making; Modle 1: adjusted for age, sex, and ethnicity; Modle 2: adjusted for age, sex, ethnicity, PIR, BMI, education level, smoking status and physical activity; Modle 3: adjusted for age, sex, ethnicity, PIR, BMI, education level, smoking status, physical activity, total calories, cardiovascular disease, hypertension and diabetes.

Figure 3

Restricted Cubic Spline Plots. Panels A–G show the relationship between CDAI, vitamin A, vitamin C, vitamin E, zinc, selenium, and carotenoids with COPD risk. Panels H–N display the relationship between CDAI, vitamin A, vitamin C, vitamin E, zinc, selenium, and carotenoids with all-cause mortality in COPD patients. Modle 3: adjusted for age, sex, ethnicity, PIR, BMI, education level, smoking status, physical activity, total calories, cardiovascular disease, hypertension and diabetes.95% CI, 95% confidence interval; OR, odds ratio; HR, hazard ratio; CDAI, Comprehensive Dietary Antioxidant Index.

Figure 4

The association between CDAI and COPD in different subgroups. 95% CI, 95% confidence interval; OR, odds ratio; CDAI, Comprehensive Dietary Antioxidant Index; BMI, body mass index; CVD, cardiovascular disease.