Lung function, COPD and alternative healthy eating index in US adults

Background There is a large burden of COPD in the US. The purpose of this study was to investigate the association between diet quality with lung function, spirometric restriction and spirometrically defined COPD in a nationally representative sample of US adults. Methods Adults (19-70 years of age) from the National Health and Nutrition Examination Survey 2007-2012 cycles were included (n=10 428). Diet quality was determined using the Alternative Healthy Eating Index (AHEI-2010). Pre-bronchodilator measurements of forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC) and the FEV1/FVC were described. Calibrated lower limit of normal (LLN) estimates were derived to determine prevalence of spirometric restriction (FVC<LLN) and COPD (FEV1/FVC ratio<LLN). Population-weighted linear and logistic regression models were used to investigate the association of AHEI-2010 and respiratory outcomes. Results The mean±SD AHEI was 45.3±12.2, equivalent to meeting 41% of the daily recommendations for optimal diet quality. Those in the highest quartile of AHEI had better FEV1 (adjusted (a)β 47.92, 95% CI 2.27-93.57) and FVC (aβ 80.23, 95% CI 34.03-126.42; p-value interaction (*) of AHEI and smoking >0.05) compared to those in quartile 1. Higher AHEI was also associated with lower odds of spirometric restriction (OR 0.23, 95% CI 0.08-0.67; p-value AHEI*ethnicity >0.05). Conclusions Diet quality was independently associated with better FEV1 and FVC and with lower odds of spirometric restriction. These findings highlight the need for research to further elucidate the possible beneficial role of diet in the preservation of lung function.