Low Dietary Nutrient Intakes and Respiratory Health in Adolescents

Abstract and Introduction

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 13 communities in the United States and Canada during the 1998 to 1999 school year. We assessed the associations between dietary factors and pulmonary function with linear mixed models, and respiratory symptoms with logistic regression using a generalized estimating equation adjusted for individual and group-level covariates.
Results: Low dietary fruit intake was associated with lower FEV₁ (– 1.3% of predicted; 95% confidence interval [CI], – 2.4 to – 0.2% of predicted), and increased odds of chronic bronchitic symptoms (odds ratio [OR], 1.36; 95% CI, 1.03 to 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% confidence interval [CI], 1.05 to 1.81), wheeze (OR, 1.34; 95% CI, 1.06 to 1.69), and asthma (OR, 1.68; 95% CI, 1.18 to 2.39) compared with higher intake. Smokers with lower dietary vitamin C intake had higher ORs of respiratory symptoms compared with smokers who had higher intake.
Conclusions: Adolescents with the lowest dietary intakes of antioxidant and antiinflammatory 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.

The effects of diet on respiratory health have been the subject of laboratory studies,^[1] observational epidemiologic studies,^[2,3] and randomized trials.^[4] Dietary intake of fruit, ascorbic acid (vitamin C), α-tocopherol (vitamin E), and beta-carotene have been positively associated with levels of FVC, FEV₁, and forced expiratory flow, midexpiratory range (FEF_{25% - 75%}) in adults.^[5,6,7] Cough, wheeze, and asthma in adults have also been associated with low dietary intake of fruit, vegetables, antioxidants, and n-3 fatty acids.^[8,9,10,11] Several studies^[12,13,14] have assessed the effects of diet on respiratory health in children, but few have focused on adolescents.

The protective effects of fruit, antioxidants, and other micronutrients may be mediated primarily in the respiratory tract lining fluid and cells.^[1] Antioxidant vitamins C and E in the respiratory tract are thought to prevent or limit the inflammatory response by reducing reactive oxygen species and inhibiting lipid peroxidation. Beta-carotene may perform a similar function.^[15] The antiinflammatory effects of n-3 fatty acids may be due to their integration into the cell membranes of the respiratory epithelium, and modulation of the inflammatory cascade.^[16]

Adolescence is a period of rapid physical growth, yet adolescents often have poor dietary habits.^[17] Micronutrients, such as antioxidants, aid in lung growth and defenses;^[18] consequently, low dietary intake may result in lower attained lung function and increased respiratory symptoms. We examined the associations of low dietary nutrient intakes with low pulmonary function and respiratory symptoms in a cohort of adolescents, the Teen Lung Study.

CHEST. 2007;132(1):238-245. © 2007 American College of Chest Physicians

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Cite this: Low Dietary Nutrient Intakes and Respiratory Health in Adolescents - Medscape - Jul 01, 2007.