Prevention of exercise-induced asthma by a natural isomer mixture of beta-carotene

Background: The unicellular alga Dunaliella bardawil was previously shown t o contain very high concentrations of beta-carotene composed of equal amoun ts of the :all-trans and 9-cis stereoisomers which differ in their physicoc hemical features and antioxidative activity. Due to the controversy regardi ng the beneficial effect of antioxidants on asthma, the acute effects of be ta-carotene of Dunaliella was assessed on airway hyperreactivity in patient s with exercise-induced asthma (EIA). Methods: Thirty-eight patients with EIA participated in our study to verify the antioxidative effect. The test was based on the following sequence: ba seline pulmonary function, 7 minutes exercise session on a motorized treadm ill, 8 minutes rest, 1-week oral random, double-blind supplementation of pl acebo or 64 mg/day beta-carotene, pulmonary functions at rest, 7 minutes ex ercise session, 8 minutes rest and again pulmonary functions. Results: All patients given placebo showed a significant postexercise reduc tion of more than 15% in their forced expiratory volume in one second (FEV1 ). Of the 38 patients who received a daily dose of 64 mg of beta-carotene f or 1 week, 20 (53%) were protected against EIA. Conclusions: Our results indicate that a daily dose of Dunaliella beta-caro tene exerts a protective effect against ETA in some patients most probably through in vivo antioxidative effect.