Ascorbic acid supplementation attenuates exercise-induced bronchoconstriction in patients with asthma.
BACKGROUND
Previous research has shown that diet can modify the bronchoconstrictor response to exercise in asthmatic subjects.


OBJECTIVE
Determine the effect of ascorbic acid supplementation on pulmonary function and several urinary markers of airway inflammation in asthmatic subjects with exercise-induced bronchoconstriction (EIB).


METHODS
Eight asthmatic subjects with documented EIB participated in a randomized, placebo controlled double-blind crossover trial. Subjects entered the study on their usual diet and were placed on either 2 weeks of ascorbic acid supplementation (1500 mg/day) or placebo, followed by a 1-week washout period, before crossing over to the alternative diet. Pre- and post-exercise pulmonary function, asthma symptom scores, fraction of exhaled nitric oxide (FENO), and urinary leukotriene (LT) C4-E4 and 9alpha, 11beta-prostagladin (PG) F2] were assessed at the beginning of the trial (usual diet) and at the end of each treatment period.


RESULTS
The ascorbic acid diet significantly reduced (p < 0.05) the maximum fall in post-exercise FEV1 (-6.4 +/- 2.4%) compared to usual (-14.3 +/- 1.6%) and placebo diet (-12.9 +/- 2.4%). Asthma symptoms scores significantly improved (p<0.05) on the ascorbic acid diet compared to the placebo and usual diet. Post-exercise FENO, LTC4-E4 and 9alpha, 11beta-PGF2 concentration was significantly lower (p<0.05) on the ascorbic acid diet compared to the placebo and usual diet.


CONCLUSIONS
Ascorbic acid supplementation provides a protective effect against exercise-induced airway narrowing in asthmatic subjects.
Tecklenburg
Sandra L
SL
Human Performance and Exercise Biochemistry Laboratory, Department of Kinesiology, Indiana University, 1025 E. 7th St, HPER 112, Bloomington, IN 47401, USA.
Mickleborough
Timothy D
TD
Fly
Alyce D
AD
Bai
Yeon
Y
Stager
Joel M
JM
D000328:Adult; D018927:Anti-Asthmatic Agents / Q000008:administration & dosage*; D001205:Ascorbic Acid / Q000008:administration & dosage*; D001249:Asthma / Q000517:prevention & control*; D001250:Asthma, Exercise-Induced / Q000178:diet therapy; D016084:Bronchoconstriction / Q000187:drug effects*; D018592:Cross-Over Studies; D019587:Dietary Supplements; D004311:Double-Blind Method; D005080:Exercise Test / Q000009:adverse effects; D005260:Female; D006801:Humans; D008297:Male; D012129:Respiratory Function Tests
D018927:Anti-Asthmatic Agents; D001205:Ascorbic Acid