Oxidative stress is thought to contribute to exercise-induced asthma (EIA), raising interest in whether antioxidant nutrients may influence post-exercise airway recovery. A small study published in Respiratory Physiology and Neurobiology (2016 Jan;220:95–101. doi:10.1016/j.resp.2015.09.012) examined the effects of antioxidant supplementation on pulmonary function in individuals with EIA.
The study used a single-blind, randomized, crossover design and included eight patients diagnosed with exercise-induced asthma and five healthy control subjects. Participants consumed a combination of antioxidants—300 IU of alpha-tocopherol (vitamin E) and 500 mg of ascorbic acid (vitamin C) daily—for three weeks. This was followed by a three-week washout period with no supplementation, after which participants crossed over to the alternate treatment phase.
At the end of each treatment period, subjects performed a 10-minute treadmill exercise test. Pulmonary function was assessed using forced vital capacity (FVC), forced expiratory volume in one second (FEV₁), forced expiratory flow between 25% and 75% of vital capacity (FEF₂₅–₇₅%), and peak expiratory flow rate (PEFR). Measurements were taken before exercise and at 1, 5, 15, and 30 minutes post-exercise.
Compared with the non-supplemented phase, antioxidant supplementation was associated with significant improvements in multiple pulmonary function measures at 5 and 15 minutes post-exercise, including FVC, FEV₁, PEFR, and FEF₂₅–₇₅%. Improvements in FEV₁ and FEF₂₅–₇₅% were also observed at 30 minutes after exercise.
The authors concluded that supplementation with vitamins E and C was associated with improved post-exercise recovery of lung function in patients with exercise-induced asthma. Given the small sample size, these findings are preliminary, but they support further investigation into the role of oxidative stress and antioxidant status in EIA.
