The effect of omega-3 fatty acids on bronchial hyperresponsiveness, sputum eosinophilia and mast cell mediators in asthma.

The effect of omega-3 fatty acids on bronchial hyperresponsiveness, sputum eosinophilia and mast cell mediators in asthma.

Chest. 2014 Oct 16;

Authors: Brannan JD, Bood J, Alkhabaz A, Balgoma D, Otis J, Delin I, Dahlén B, Wheelock CE, Nair P, Dahlén SE, O’Byrne PM

Abstract
Background: Omega-3 fatty acid supplements have been reported to inhibit exercise-induced bronchospasm (EIB). It has not been determined if omega-3 supplements inhibit airway sensitivity to inhaled mannitol, a test for bronchial hyperresponsiveness (BHR) and model for EIB in persons with mild-moderate asthma.
Methods: In a double-blind, crossover trial, asthmatic subjects who had BHR to inhaled mannitol (n=23, 14 males, mean age 28, half taking regular inhaled corticosteroids) were randomized to omega-3 supplements (4.0g/day eicosapentaenoic acid and 2.0g/day docosahexaenoic acid) or matching placebo for 3-weeks, separated by a 3-week washout. The primary outcome was the provoking dose of mannitol (mg) required to cause a 15% fall in FEV1 (PD15). Secondary outcomes were sputum eosinophil counts, spirometry, asthma control questionnaire (ACQ), serum triacylglycerides and lipid mediator profile in urine and serum.
Results: PD15 (geometric mean, 95% CI) to mannitol following supplementation with omega-3s (78 mg, 51-119) was not different to placebo (88mg, 56-139)(p=0.5). There were no changes in sputum eosinophils (mean±SD) in a sub-group of subjects (omega-3s;8.4±8.2%: placebo;7.8±11.8%,p=0.9)(n=11). At the end of each treatment period there were no differences in FEV1 (% predicted)(omega-3s;85±13%: placebo;84±11%,p=0.9) or ACQ (omega-3s;1.1±0.5%: placebo;1.1±0.5%,p=0.9)(n=23). Omega-3s caused significant lowering of blood triglycerides and expected shifts in serum fatty acids and eicosanoid metabolites, confirming adherence to the supplements; however, no changes were observed in urinary mast cell mediators.
Conclusion: Three weeks of omega-3 supplements does not improve BHR to mannitol, decrease sputum eosinophils or inhibit urinary excretion of mast cell mediators in persons with mild-moderate asthma indicating that dietary omega-3 supplementation is not useful in the short-term treatment of asthma.
Clinical Trial Registration: URL: http://www.clinicaltrials.gov (Identifier Number NCT00526357).

PMID: 25321659 [PubMed – as supplied by publisher]

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