Tangeretin Reduces Severity Of Exercise-induced Bronchoconstriction In Professional Athletes

PURPOSE: To investigate the effects of tangeretin supplementation on auxiliary indicators of exercise-induced bronchoconstriction (EIB), thereby evaluating its therapeutic effects. METHODS: Placebo controlled double-blinded randomized trial was performed on 30 elite athletes with EIB (14 females and 16 males). They were paired and divided into tangeretin intervention group (TIG) or placebo control group (PCG). Both group performed bronchial provocation tests before and after invention. Airway inflammation (eosinophi, neutrophil, basophil, IL-5, IL-8, CC16, IgE), pulmonary ventilation (FEV1, FVC, rate of decline of FEV1) and respiratory symptoms (cough, wheeze, chest tightness) were evaluated before and after the bronchial provocation tests. Chi-square test, independent sample t test and repeated measure analysis of variances were performed. RESULTS: TIG showed significantly lower level of the eosinophil count (P = 0.049), neutrophil count (P = 0.039), IL-5 (P = 0.037), IL-8 (P = 0.003) and IgE (P = 0.011) than the baseline after intervention, and significantly lower level of the IL-5 (P = 0.022) and IL-8 (P = 0.012) than PCG at T5. TIG displayed significantly higher value of the FEV1 (P < 0.01), FVC (P < 0.01), PEF (P = 0.047) and MMF (P = 0.039) than those in the first exercise challenge test (ECT1). Meanwhile, 6 athletes became EIB-negative after intervention, and negative conversion rate of EIB was 40.00%. Additionally, the number of cough symptoms decreased from 9 to 3 and dyspnea from 4 to 2 in TIG. CONCLUSION: Tangeretin supplementation can significantly improve pulmonary ventilation function through inhibiting airway inflammation and relieving respiratory symptoms when athletes with EIB performing high-intensity exercise. Simultaneously, the EIB related symptoms were disappeared for some athletes with EIB after intervention. Tangeretin supplementation showed good therapeutic effects on EIB and was recommended to professional athletes with EIB.