Treating asthma with omega-3 fatty acids: where is the evidence? A systematic review
Considerable interest exists in the potential therapeutic value of dietary supplementation with the omega-3 fatty acids. Given the interplay between pro-inflammatory omega-6 fatty acids, and the less pro-inflammatory omega-3 fatty acids, it has been thought that the latter could play a key role in treating or preventing asthma. The purpose was to systematically review the scientific-medical literature in order to identify, appraise, and synthesize the evidence for possible treatment effects of omega-3 fatty acids in asthma.
Medline, Premedline, Embase, Cochrane Central Register of Controlled Trials, CAB Health, and, Dissertation Abstracts were searched to April 2003. We included randomized controlled trials (RCT's) of subjects of any age that used any foods or extracts containing omega-3 fatty acids as treatment or prevention for asthma. Data included all asthma related outcomes, potential covariates, characteristics of the study, design, population, intervention/exposure, comparators, and co interventions.
Ten RCT's were found pertinent to the present report.
Given the largely inconsistent picture within and across respiratory outcomes, it is impossible to determine whether or not omega-3 fatty acids are an efficacious adjuvant or monotherapy for children or adults. Based on this systematic review we recommend a large randomized controlled study of the effects of high-dose encapsulated omega-3 fatty acids on ventilatory and inflammatory measures of asthma controlling diet and other asthma risk factors. This review was limited because Meta-analysis was considered inappropriate due to missing data; poorly or heterogeneously defined populations, interventions, intervention-comparator combinations, and outcomes. In addition, small sample sizes made it impossible to meaningfully assess the impact on clinical outcomes of co-variables. Last, few significant effects were found.
- McKeever, TM, Britton, J (2004) Diet and asthma. Am J Respir Crit Care Med 170: pp. 725-729 CrossRef
- Heart, N, Institute, LB (1997) Expert Panel Report 2: Guidelines for the diagnosis and management of asthma. Bethesda, National Institutes of Health
- Simopoulos, AP (2002) The importance of the ratio of omega-6/omega-3 essential fatty acids. Biomed Pharmacother 56: pp. 365-379 CrossRef
- Busse, WW, Lemanske, RFJ (2001) Asthma. N Engl J Med 344: pp. 350-362 CrossRef
- National Asthma Education and Prevention Program. Expert Panel Report: Guidelines for the Diagnosis and Management of Asthma Update on Selected Topics--2002. J Allergy Clin Immunol 110: pp. S141-S219 CrossRef
- Horrobin, DF (1987) Low prevalences of coronary heart disease (CHD), psoriasis, asthma and rheumatoid arthritis in Eskimos: are they caused by high dietary intake of eicosapentaenoic acid (EPA), a genetic variation of essential fatty acid (EFA) metabolism or a combination of both?. Med Hypotheses 22: pp. 421-428 CrossRef
- Gil, A (2002) Polyunsaturated fatty acids and inflammatory diseases. Biomed Pharmacother 56: pp. 388-396 CrossRef
- Schachter, HM, Reisman, J, Tran, K, Dales, B, Kourad, K, Barnes, D, Sampson, M, Morrison, A, Gaboury, I, Blackman, J (2004) Health Effects of Omega-3 Fatty Acids on Asthma. Rockville MD, AHRQ Publication No. 04-E013-2
- Woods RK, Thien FC, Abramson MJ: Dietary marine fatty acids (fish oil) for asthma in adults and children. Cochrane Database Syst Rev 2002, CD001283.
- Jadad, AR (1998) Randomised controlled trials. London, BMJ Publishing Group
- Moher, D, Cook, DJ, Eastwood, S, Olkin, I, Rennie, D, Stroup, DF (1999) Improving the quality of reports of meta-analyses of randomised controlled trials: the QUOROM statement. Quality of Reporting of Meta-analyses. Lancet 354: pp. 1896-1900 CrossRef
- Jadad, AR, Moore, RA, Carroll, D, Jenkinson, C, Reynolds, DJ, Gavaghan, DJ, McQuay, HJ (1996) Assessing the quality of reports of randomized clinical trials: is blinding necessary?. Control Clin Trials 17: pp. 1-12 CrossRef
- Schulz, KF, Chalmers, I, Hayes, RJ, Altman, DG (1995) Empirical evidence of bias. Dimensions of methodological quality associated with estimates of treatment effects in controlled trials. JAMA 273: pp. 408-412 CrossRef
- Downs, SH, Black, N (1998) The feasibility of creating a checklist for the assessment of the methodological quality both of randomised and non-randomised studies of health care interventions. J Epidemiol Community Health 52: pp. 377-384 CrossRef
- McDonald, CV (1990) Effect of fish-oil derived omega-3 fatty acid supplements on asthma control. Aust N Z J Med 20: pp. 526
- Nagakura, T, Matsuda, S, Shichijyo, K, Sugimoto, H, Hata, K (2000) Dietary supplementation with fish oil rich in omega-3 polyunsaturated fatty acids in children with bronchial asthma. Eur Respir J 16: pp. 861-865 CrossRef
- Hodge, L, Salome, CM, Hughes, JM, Liu-Brennan, D, Rimmer, J, Allman, M, Pang, D, Armour, C, Woolcock, AJ (1998) Effect of dietary intake of omega-3 and omega-6 fatty acids on severity of asthma in children. Eur Respir J 11: pp. 361-365 CrossRef
- Arm, JP, Horton, CE, Mencia-Huerta, JM, House, F, Eiser, NM, Clark, TJ, Spur, BW, Lee, TH (1988) Effect of dietary supplementation with fish oil lipids on mild asthma. Thorax 43: pp. 84-92 CrossRef
- Okamoto, M, Mitsunobu, F, Ashida, K, Mifune, T, Hosaki, Y, Tsugeno, H, Harada, S, Tanizaki, Y (2000) Effects of dietary supplementation with n-3 fatty acids compared with n-6 fatty acids on bronchial asthma. Intern Med 39: pp. 107-111 CrossRef
- Thien, FC, Mencia-Huerta, JM, Lee, TH (1993) Dietary fish oil effects on seasonal hay fever and asthma in pollen-sensitive subjects. Am Rev Respir Dis 147: pp. 1138-1143
- Stenius-Aarniala, B, Aro, A, Hakulinen, A, Ahola, I, Seppala, E, Vapaatalo, H (1989) Evening primose oil and fish oil are ineffective as supplementary treatment of bronchial asthma. Ann Allergy 62: pp. 534-537
- Kirsch, CM, Payan, DG, Wong, MY, Dohlman, JG, Blake, VA, Petri, MA, Offenberger, J, Goetzl, EJ, Gold, WM (1988) Effect of eicosapentaenoic acid in asthma. Clin Allergy 18: pp. 177-187 CrossRef
- Emelyanov, AF (2002) Treatment of asthma with lipid extract of New Zealand green-lipped mussel: a randomised clinical trial. Eur Respir J 20: pp. 596-600 CrossRef
- Dry, J, Vincent, D (1991) Effect of a fish oil diet on asthma: results of a 1-year double-blind study. Int Arch Allergy Appl Immunol 95: pp. 156-157 CrossRef
- Hodge L: Effect of fish oil supplements on severity of asthma in children. Annu Sci Meet Thorac Soc Aust N Z 1997.
- Payan, DG, Wong, MY, Chernov-Rogan, T, Valone, FH, Pickett, WC, Blake, VA, Gold, WM, Goetzl, EJ (1986) Alterations in human leukocyte function induced by ingestion of eicosapentaenoic acid. J Clin Immunol 6: pp. 402-410 CrossRef
- Arm, JP, Horton, CE, Spur, BW, Mencia-Huerta, JM, Lee, TH (1989) The effects of dietary supplementation with fish oil lipids on the airways response to inhaled allergen in bronchial asthma. Am Rev Respir Dis 139: pp. 1395-1400
- Mickleborough, TD, Lindley, MR, Ionescu, AA, Fly, AD (2006) Protective effect of fish oil supplementation on exercise-induced bronchoconstriction in asthma. Chest 129: pp. 39-49 CrossRef
- The pre-publication history for this paper can be accessed here:http://www.biomedcentral.com/1472-6882/6/26/prepub
- Treating asthma with omega-3 fatty acids: where is the evidence? A systematic review
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BMC Complementary and Alternative Medicine
- Online Date
- July 2006
- Online ISSN
- BioMed Central
- Additional Links
- Author Affiliations
- 1. Department of Pediatrics, Children's Hospital of Eastern Ontario, Ottawa, ON, Canada
- 2. Chalmers Research Group, Children's Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada
- 3. The Clinical Epidemiology Unit, Ottawa Health Research Institute, Ottawa Hospital and University of Ottawa, Ottawa, ON, Canada
- 4. Canadian Coordinating Office for Health Technology Assessment, Ottawa, ON, Canada
- 5. Complementary Medicine Program, University of Maryland, Baltimore, MD, USA