Objective: To determine whether caffeine consumption affects bronchoprovocation challenge (BPC).
Design: A prospective, double-blind, placebo-controlled, randomized, crossover trial.
Patients: Eleven nonsmoking men, aged 18 to 42 years, with normal baseline spirometry and evidence of exercise-induced bronchospasm.
Intervention: On three separate test days, each individual received, in random order, either placebo, 5 mg/kg caffeine, or 10 mg/kg caffeine, and then underwent BPC with eucapnic voluntary hyperventilation (EVH).
Results: Caffeine (10 mg/kg) significantly reduced bronchoconstriction compared to placebo (p = 0.02). The reduction in bronchoconstriction correlated with the serum level of caffeine (p = 0.014).
Conclusions: Caffeine decreases bronchoconstriction due to EVH. Caffeine should be eliminated from diet prior to BPC.