Effect of vitamin C administration on leukocyte vitamin C level and severity of bronchial asthma

Oxidative stress mediated by reactive oxygen species is known to contribute to the inflammatory process of bronchial asthma. Reactive oxygen species are released into the bronchial tree by activated inflammatory cells. In this study, we aimed to determine the effect of vitamin C administration on leukocyte vitamin C level as well as severity of asthma. In this double blind clinical trial study we evaluated 60 patients with chronic stable asthma. The patients were divided into two groups (A and B) including 30 patients in each group. Patients in these groups were matched according to their age, weight, height, gender, BMI and drug consumption. In addition to standard asthma treatment (according to stepwise therapy in 4th step of bronchial asthma) in which the patients were controlled appropriately, group A received 1000 mg vitamin C daily and group B received placebo. At the baseline and after one month treatment, non-fasting blood samples were drawn for laboratory evaluations. Asthmatic patient's clinical condition was evaluated through standard pulmonary function test (PFT). The mean (±SD) leukocyte vitamin C level in group A at the baseline and after one month treatment with 1000 mg/day vitamin C, were 0.0903 (±0.0787) µg/108 leukocytes and 0.1400 (±0.0953) µg/108 leukocytes respectively (P<0.05). The mean (±SD) leukocyte vitamin C level in group B at the baseline and after one month administration of placebo, were 0.0867 (±0.0629) µg/108 leukocytes and 0.0805(±0.0736) µg/108 leukocytes respectively. The leukocyte vitamin C level in group A was higher than those of group B after one month treatment with vitamin C and placebo and the difference was statistically significant (P<0.05). Comparing PFT (FEV1, FVC and FEV1/FVC) in group B during the study period showed a significant increase in FEV1 (P<0.05), while the other two parameters remained unchanged. In group A, who received 1000 mg/day vitamin C, none of the spirometry parameters changed after one month treatment, indicating no effect of vitamin C treatment in the spirometry parameters.