Effect of n–3 Polyunsaturated Fatty Acids in Asthma after Low-Dose Allergen Challenge

Abstract

Background: We investigated the anti-inflammatory potential of n–3 polyunsaturated fatty acids (PUFA) on specific bronchial inflammation. Allergic asthmatics were challenged using a low-dose allergen provocation model. Methods: Our parallel double-blinded study randomly assigned 23 house dust mite-allergic asthmatics (aged 22–29 years; 13 females, 10 males) to dietary supplementation with either an n–3 PUFA-enriched fat blend (0.69 g/day) or placebo for 5 weeks. After 3 weeks, the patients were challenged daily with low doses of mite allergen for 2 weeks. Primary outcome parameters were effects on lung function (forced expiratory volume in 1 s, FEV₁) and exhaled nitric oxide (eNO) as a marker of bronchial inflammation. Results: Even before the bronchial challenge, eNO was significantly lower in the n–3 PUFA group (p = 0.014). Levels of eNO increased during allergen exposure in both groups, but differences in means were significantly lower in the n–3 PUFA group (p = 0.022). During the low-dose allergen challenge, there were no differences between the groups with regard to symptoms, FEV₁ or the allergen dose required to induce deterioration of lung function (PD₂₀). Numbers of sputum eosinophils did not differ significantly, while serum eosinophils (10.1 ± 0.1.84 vs. 5.79 ± 0.69%) as well as changes in eosinophilic cationic protein (20.5 ± 9.93 vs. –1.68 ± 4.36 ng/ml) and in vitro cysteinyl leukotriene release (2,889 ± 872 vs. 1,120 ± 173 ng/ml) were significantly lower in the n–3 PUFA group (p < 0.05 each). Conclusion: Our results provide evidence that dietary supplementation with n–3 PUFA is able to reduce bronchial inflammation even after low-dose allergen challenge.