Methods: Data were obtained from a sample of 6,726 subjects aged 40+ from the Third National Health and Nutrition
Examination Survey. The forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) were measured
using spirometry. Gender-, ethnicity-, and age-specific equations were used to calculate the lower limit of normal (LLN)
to define obstructive lung disorder as: observed FEV1/FVC ratio and FEV1 below respective LLN. Zinc intake was
assessed by questionnaire. Logistic regression analysis was applied to investigate the associations of interest.