Antioxidant nutrients and pulmonary function: The Third National Health and Nutrition Examination Survey (NHANES III)

Recent studies of chronic obstructive pulmonary disease have raised interes t in its relation to nutrition. Several dietary antioxidants have been posi tively associated with lung function in healthy, general population samples . This study considered the separate and joint effects of vitamin C, vitami n E, beta-carotene, and selenium intake and used both dietary assessment an d serum biomarkers of antioxidant status. The authors used data from the Th ird National Health and Nutrition Examination Survey comprising a sample re presentative of the US population in 1988-1994 (n = 18,162 subjects aged gr eater than or equal to 17 years). Multiple linear regression analysis exami ned the separate and joint effects of the antioxidants on the ratio of forc ed expiratory volume in the first second (FEV1)/height(2) adjusted for cova riates. Each of the dietary and serum antioxidant nutrients was significant ly associated with FEV1. When they were considered simultaneously (dietary and serum variables considered in separate models), independent association s were observed for most nutrients. Serum beta-carotene was less positively associated with FEV1 in smokers than nonsmokers, while serum selenium had a stronger positive association with FEV1 in smokers. The authors found tha t higher levels of antioxidant nutrients are associated with better lung fu nction. The finding that the antioxidants differ in both their overall asso ciation with lung function and in whether this association varies by smokin g status has implications for further research.