Blocking effect of vitamin C in exercise-induced asthma.
OBJECTIVE
To determine if vitamin C (ascorbic acid) has a protective effect on the hyperreactive airways of patients with exercise-induced asthma (EIA).


METHODS
All the patients underwent pulmonary function tests at rest, before and 1 hour after receiving 2 g of oral ascorbic acid. They were then randomly assigned in a double-blind manner to receive 2 g of ascorbic acid or a placebo 1 hour before a 7-minute exercise session on a treadmill. Pulmonary function tests were performed after an 8-minute rest. This procedure was repeated 1 week later, with each patient receiving the alternative medication.


METHODS
A university hospital.


METHODS
Twenty patients with asthma (13 males and 7 females), with ages ranging from 7 to 28 years (mean, 13.8 years). All patients who had a decline of at least 15% in their forced expiratory volume in 1 second after a standard exercise test on a motorized treadmill received a diagnosis of EIA. MAIN-OUTCOME MEASURES: All patients were advised to stop using their regular asthma medication or bronchodilator 12 hours before the test. Pulmonary function tests were performed in the same ambient conditions on all patients.


RESULTS
All patients received a diagnosis of EIA. Ascorbic acid administration did not change the results of pulmonary functions at rest after 1 hour. In 9 patients, a protective effect on exercise-induced hyperreactive airways was documented. Four of 5 patients who received ascorbic acid and documented a protective effect on EIA continued to receive ascorbic acid, 0.5 g/d, for 2 more weeks with the same protective effect.


CONCLUSIONS
The efficacy of vitamin C in preventing EIA cannot be predicted. However, vitamin C may have a protective effect on airway hyperreactivity in some patients with EIA.
Cohen
H A
HA
Pediatric Ambulatory Clinic, Rabin Medical Center, Petach Tiqva, Israel.
Neuman
I
I
Nahum
H
H
D000284:Administration, Oral; D000293:Adolescent; D000328:Adult; D001205:Ascorbic Acid / Q000627:therapeutic use*; D001250:Asthma, Exercise-Induced / Q000517:prevention & control*; D002648:Child; D004311:Double-Blind Method; D005260:Female; D005541:Forced Expiratory Volume / Q000187:drug effects; D006801:Humans; D008297:Male; D012129:Respiratory Function Tests
D001205:Ascorbic Acid