Purpose: To compare the effects of two mono-therapies (fish oil and vitamin C) alone and in combination, on airway inflammation and the bronchoconstrictor response to eucapnic voluntary hyperpnea (EVH) in asthmatics.
Methods: Sixteen asthmatic subjects with hyperpnea-induced bronchoconstriction (HIB) entered the study on their usual diet (pre-treatment, n=16) and then randomly assigned to receive either active vitamin C tablets (1.5 g) and placebo fish oil capsules (n=8) or active fish oil capsules (3.2 g EPA/2.0 g DHA) and placebo vitamin C tablets (n=8) taken for 3 weeks. Thereafter, all subjects (combination treatment; n=16) underwent a further 3-week treatment period consisting of active vitamin C tablets and active fish oil capsules taken daily (NT01057615).
Results: HIB was significantly inhibited (p<0.017) by fish oil, vitamin C and combination treatment compared to pre-treatment (usual diet); percent fall in post-EVH forced expiratory volume in 1-sec was 18.8 + 5.7%, 9.7 + 5.4%, 10.5 ± 10.2% and 10.7 ± 9.3% on the usual diet, fish oil, vitamin C and combination treatment respectively. All three treatments, compared to the usual diet, were associated with a significant reduction (p<0.017) in the fraction of exhaled nitric oxide and bronchodilator use, and improvement in asthma symptom scores and exhaled breath condensate pH. There was no significant difference between treatment groups for any dependent variables.
Conclusion: While fish oil and vitamin C supplementation are both effective in attenuating airway inflammation and HIB, combining these two nutrients does not confer a greater anti-inflammatory effect or suppression of HIB than either intervention alone.