Background: Epidemiologic studies have indicated that a diet rich in fruit, antioxidants and n-3 fatty acids may contribute to optimal respiratory health. We investigated whether low dietary nutrient intakes were associated with lower pulmonary function and higher reporting of respiratory symptoms in adolescents.

Methods: We examined the association of dietary factors (fruit, vegetables, vitamins C and E, beta-carotene, retinol, n-3 fatty acids) with respiratory health in a cohort of 2,112 twelfth-grade students in twelve communities in the U.S. and Canada during the 1998-1999 school year. We assessed the associations between dietary factors and pulmonary function with linear mixed models, and respiratory symptoms with logistic regression using generalized estimating equations (GEE), adjusted for individual and group level covariates.

Results: Low dietary fruit intake was associated with lower forced expiratory flow in one second (-1.3%; 95% CI: -2.4%, -0.2%) and increased odds of chronic bronchitic symptoms (OR=1.36; 95% CI: 1.03, 1.73) compared with higher intake. Low dietary n-3 fatty acids intake was associated with increased odds of chronic bronchitic symptoms (OR=1.37; 95% CI: 1.05, 1.81), wheeze (OR=1.34; 95% CI: 1.06, 1.69), and asthma (OR=1.68; 95% CI: 1.18, 2.39) compared with higher intake. Smokers with lower dietary vitamin C intake had higher odds ratios of respiratory symptoms compared with smokers who had higher intake.

Conclusions: Adolescents with the lowest dietary intakes of antioxidant and anti-inflammatory micronutrients had lower pulmonary function and increased respiratory symptoms, especially among smokers, suggesting that adequate dietary intake may promote respiratory health and lessen the effects of oxidative stress.

PMID: 17475634

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