Investigation of the association between dietary intake, disease severity and airway inflammation in asthma

Background and objective: Dietary intake is an important modifiable risk factor for asthma and may be related to disease severity and inflammation, through the effects of intake of anti-oxidant-rich foods and pro-inflammatory nutrients. This study aimed to examine dietary intake in asthma in relation to asthma severity, lung function, inhaled corticosteroid use, leptin levels and inflammation. Methods: Food frequency questionnaires, spirometry and hypertonic saline challenge were completed by 137 stable asthmatics and 65 healthy controls. Plasma leptin was analysed by immunoassay. Induced sputum differential cell counts were determined. Results: Subjects with severe persistent asthma consumed more fat and less fibre as compared with healthy controls (odds ratio 1.04 (95% confidence interval: 1.01-1.07), P = 0.014) (odds ratio 0.94 (95% confidence interval: 0.90-0.99), P = 0.018). Among asthmatics, higher fat and lower fibre intakes were associated with lower forced expiratory volume in 1 s and airway eosinophilia. Leptin levels were increased in both male and female asthmatics as compared with healthy controls. No association existed among asthmatics between corticosteroid use and dietary intake. Conclusions: It was found that asthmatics within the subgroup of severe persistent asthma have a different pattern of dietary intake as compared with healthy controls, which was associated with lower lung function and increased airway inflammation.