Dietary intake of vitamin A, lung function and incident asthma in childhood
Mohammad Talaei, David A. Hughes, Osama Mahmoud, Pauline Emmett, Raquel Granell, Stefano Guerra, Seif O. Shaheen
Abstract
Background Longitudinal epidemiological data are scarce on the relationship between dietary intake of vitamin A and respiratory outcomes in childhood. We investigated whether a higher intake of preformed vitamin A or pro-vitamin β-carotene in mid-childhood is associated with higher lung function and with asthma risk in adolescence. Methods In the Avon Longitudinal Study of Parents and Children, dietary intakes of preformed vitamin A and β-carotene equivalents were estimated by food frequency questionnaire at 7 years of age. Post-bronchodilator forced expiratory volume in 1 s (FEV 1 ), forced vital capacity (FVC) and forced expiratory flow at 25–75% of FVC (FEF 25–75% ) were measured at 15.5 years and transformed to z-scores. Incident asthma was defined by new cases of doctor-diagnosed asthma at age 11 or 14 years. Results In multivariable adjusted models, a higher intake of preformed vitamin A was associated with higher lung function and a lower risk of incident asthma: comparing top versus bottom quartiles of intake, regression coefficients for FEV 1 and FEF 25–75% were 0.21 (95% CI 0.05–0.38; p trend =0.008) and 0.18 (95% CI 0.03–0.32; p trend =0.02), respectively; odds ratios for FEV 1 /FVC below the lower limit of normal and incident asthma were 0.49 (95% CI 0.27–0.90; p trend =0.04) and 0.68 (95% CI 0.47–0.99; p trend =0.07), respectively. In contrast, there was no evidence for association with β-carotene. We also found some evidence for modification of the associations between preformed vitamin A intake and lung function by BCMO1 , NCOR2 and SCGB1A1 gene polymorphisms. Conclusion A higher intake of preformed vitamin A, but not β-carotene, in mid-childhood is associated with higher subsequent lung function and lower risk of fixed airflow limitation and incident asthma.