title: The effect of omega-3 fatty acids on bronchial hyperresponsiveness, sputum eosinophilia, and mast cell mediators in asthma.
abstract: BACKGROUND
  Omega-3 fatty acid supplements have been reported to inhibit exercise-induced bronchoconstriction (EIB). It has not been determined whether omega-3 supplements inhibit airway sensitivity to inhaled mannitol, a test for bronchial hyperresponsiveness (BHR) and model for EIB in people with mild to moderate asthma.
  
  
  METHODS
  In a double-blind, crossover trial, subjects with asthma who had BHR to inhaled mannitol (n = 23; 14 men; mean age, 28 years; one-half taking regular inhaled corticosteroids) were randomized to omega-3 supplements (4.0 g/d eicosapentaenoic acid and 2.0 g/d docosahexaenoic acid) or matching placebo for 3 weeks separated by a 3-week washout. The primary outcome was the provoking dose of mannitol (mg) to cause a 15% fall in FEV1 (PD15). Secondary outcomes were sputum eosinophil count, spirometry, Asthma Control Questionnaire (ACQ) score, serum triacylglyceride level, 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 mg) was not different from placebo (88 mg, 56-139 mg, P = .5). There were no changes in sputum eosinophils (mean ± SD) in a subgroup of 11 subjects (omega-3, 8.4% ± 8.2%; placebo, 7.8% ± 11.8%; P = .9). At the end of each treatment period, there were no differences in FEV1 % predicted (omega-3, 85% ± 13%; placebo, 84% ± 11%; P = .9) or ACQ score (omega-3, 1.1% ± 0.5%; placebo, 1.1% ± 0.5%; P = .9) (n = 23). Omega-3s caused significant lowering of blood triglyceride levels 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.
  
  
  CONCLUSIONS
  Three weeks of omega-3 supplements does not improve BHR to mannitol, decrease sputum eosinophil counts, or inhibit urinary excretion of mast cell mediators in people with mild to moderate asthma, indicating that dietary omega-3 supplementation is not useful in the short-term treatment of asthma.
  
  
  BACKGROUND
  ClinicalTrials.gov; No.: NCT00526357; URL: www.clinicaltrials.gov.
authors.affiliation: Firestone Institute for Respiratory Health, St. Joseph's Healthcare and McMaster University, Hamilton, ON, Canada. Electronic address: john.brannan@sydney.edu.au.
authors.forename: John D
authors.initials: JD
authors.lastname: Brannan
authors.affiliation: National Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden; Department of Medicine, Karolinska University Hospital Huddinge, Karolinska Institutet, Stockholm, Sweden; Centre for Allergy Research, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Johan
authors.initials: J
authors.lastname: Bood
authors.affiliation: Firestone Institute for Respiratory Health, St. Joseph's Healthcare and McMaster University, Hamilton, ON, Canada.
authors.forename: Ahmad
authors.initials: A
authors.lastname: Alkhabaz
authors.affiliation: Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden; National Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
authors.forename: David
authors.initials: D
authors.lastname: Balgoma
authors.affiliation: Firestone Institute for Respiratory Health, St. Joseph's Healthcare and McMaster University, Hamilton, ON, Canada.
authors.forename: Joceline
authors.initials: J
authors.lastname: Otis
authors.affiliation: National Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden; Centre for Allergy Research, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Ingrid
authors.initials: I
authors.lastname: Delin
authors.affiliation: Department of Medicine, Karolinska University Hospital Huddinge, Karolinska Institutet, Stockholm, Sweden; Centre for Allergy Research, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Barbro
authors.initials: B
authors.lastname: Dahlén
authors.affiliation: Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden; Centre for Allergy Research, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Craig E
authors.initials: CE
authors.lastname: Wheelock
authors.affiliation: Firestone Institute for Respiratory Health, St. Joseph's Healthcare and McMaster University, Hamilton, ON, Canada.
authors.forename: Parameswaran
authors.initials: P
authors.lastname: Nair
authors.affiliation: National Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden; Centre for Allergy Research, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Sven-Erik
authors.initials: SE
authors.lastname: Dahlén
authors.affiliation: Firestone Institute for Respiratory Health, St. Joseph's Healthcare and McMaster University, Hamilton, ON, Canada.
authors.forename: Paul M
authors.initials: PM
authors.lastname: O'Byrne
mesh_terms: D000328:Adult; D001249:Asthma / Q000503:physiopathology*; D016535:Bronchial Hyperreactivity / Q000188:drug therapy*; D018592:Cross-Over Studies; D019587:Dietary Supplements; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D004802:Eosinophilia / Q000188:drug therapy; D004804:Eosinophils; D015525:Fatty Acids, Omega-3 / Q000378:metabolism / Q000494:pharmacology / Q000627:therapeutic use*; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D007958:Leukocyte Count; D008297:Male; D008353:Mannitol / Q000008:administration & dosage; D008407:Mast Cells / Q000502:physiology; D013183:Sputum / Q000166:cytology; D014280:Triglycerides / Q000097:blood; D055815:Young Adult
chemical_list: D015525:Fatty Acids, Omega-3; D014280:Triglycerides; D008353:Mannitol