Objective: This case-controlled study investigated differences in dietary intake between a population with and without asthma.
Methods: A case-controlled study of the dietary intakes of subjects with asthma (n = 54, average age 23.59 +/- 9.6 y; group 1) and healthy subjects (n = 54, average age 27.07 +/- 7.2 y; group 2) using 3-d dietary intakes was undertaken. Fifty-four patients with asthma and healthy non-asthmatic subjects matched by age and sex were selected. All enrolled subjects (asthmatic and non-asthmatic) received instruction to record their daily dietary intake for 3 d including a weekend day. Pulmonary function tests were performed in asthmatic patients.
Results: Total energy intake and distribution of energy were normal in both groups (39.7% carbohydrates in group 1 and 41% in group 2, 19.4% proteins in group 1 and 22% in group 2, and 40.9% lipids in group 1 and 37% in group 2). A higher intake of vitamin A (642 +/- 399 microg/d) was detected in non-asthmatic than in asthmatic subjects (459 +/- 242 microg/d, P < 0.05). Daily intake of vitamin C was higher in non-asthmatic subjects (124 +/- 70 mg) than in asthmatic subjects (93.1 +/- 63.9 mg, P < 0.05). Vitamin E intake was higher in non-asthmatic subjects (7.3 +/- 1.2 mg) than in asthmatic subjects (5.1 +/- 2.3 mg, P < 0.05). Correlation analysis between daily intake and forced expiratory volume in 1 s (FEV1) in group 1 (asthmatic subjects) showed a positive association between omega-3 fatty acids (g/d) and FEV1 (r = 0.6, P < 0.05). No statistical correlations were detected between omega-6 and omega-9 fatty acid intakes and FEV1. Multivariant analysis with the dependent variable of FEV1 showed that only vitamin C and omega-3 fatty acids remained in the model after adjusting for smoking, age, and sex (F = 14.24, P < 0.001), with an increase of 0.25% (95% confidence interval = 0.1-0.4) in FEV1 with each 1 mug of vitamin C intake and an increase of 99.3% (95% confidence interval = 81.59-137.19) in FEV1 with each 1 g of omega-3 fatty acids.
Conclusions: Asthmatic patients have a lower intake of vitamins A, C, and E than do non-asthmatic subjects. Intake of omega-3 fatty acids was correlated with FEV1.