Non-linear Association between Composite Dietary Antioxidant Index and Pulmonary Function: A Cross-Sectional Study Based on NHANES 2007-2012

Background The relationship between pulmonary function and various diseases was well established; however, limited research has been conducted to examine the association between diet and pulmonary function. Investigating the potential correlation between the composite dietary antioxidant index (CDAI) in diet and pulmonary function could provide valuable insight into the role of diet in improving pulmonary function. Methods This cross-sectional population-based study utilized data from National Health and Nutrition Examination Survey (NHANES 2007 - 2012). Weighted multivariate linear regression analysis and stratified analysis were constructed to analyze the association of CDAI and pulmonary function—forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC). Restricted Cubic Spline was employed to detect the non-linearly association between them. Results In total, 8926 individuals from the NHANES dataset represented around 149.48 million non-institutionalized residents of the United States (mean age: 44.08 ± 0.43 years, with females accounting for 50.03%). The weighted multivariable linear regression models showed a positive association between CDAI and pulmonary function, consistent with the sensitive analysis. When compared to the lowest quartile, the beta value (β) and 95% confidence intervals (CIs) for FVC in Q3 and Q4 CDAI groups were 117.18 (55.43, 178.93), and 143.57 (97.23, 189.91), respectively; for FEV1, they were 70.64 (21.21, 120.07), and 76.68 (25.73, 127.63). Conclusions Our investigation found that CDAI levels were non-linearly and positively associated to FVC and FEV1. Based on these results, supplementing the combined antioxidants derived from food may be a promising and effective strategy for improving pulmonary function.