The attenuation of exercise-induced bronchospasm by ascorbic acid.

In order to study the potential benefit of ascorbic acid in asthma we investigated its role in exercise-induced bronchospasm (EIB). Twelve asthmatic subjects were recruited on the basis of findings compatible with EIB. On two subsequent days the subjects ingested 500 mg. of ascorbic acid or a placebo. The study was performed in a double-blind randomized fashion. Partial and maximal expiratory flow volume (PEFV and MEFV) curves were used to determine pulmonary function changes. Pretreatment with ascorbic acid led to a significant attenuation of the bronchospasm seen five minutes after exercise compared to placebo, as measured by FVC (0.23 +/- 0.08 L decrease after ascorbic acid, 0.48 +/- 0.14 L decrease after placebo) and by FEV1 (0.24 +/- 0.06 decrease after ascorbic acid, 0.44 +/- 0.14 decrease after placebo) Mean +/- SE). These results suggest a mild antibronchospastic action of ascorbic acid in subjects with EIB.