The association of dietary intake and supplementation of specific polyunsaturated fatty acids with inflammation and functional capacity in chronic obstructive pulmonary disease: a systematic review

OBJECTIVE: This systematic review sought to identify the association of dietary intake and supplementation of specific polyunsaturated fatty acids with inflammation and function in people with chronic obstructive pulmonary disease (COPD). DATA SOURCES: We searched electronic databases including PubMed, CINAHL, MEDLINE, EMBASE, The Cochrane Library, ProQuest Dissertations and Theses, Scopus, Google Scholar, Trove, and WHO International Clinical Trials Registry Platform and reference lists of retrieved articles published prior to August 2014. INCLUSION CRITERIA: We considered observational studies that evaluated dietary intake of omega-3 (eicosapentaenoic acid, docosahexaenoic acid or α-linolenic acid) and/or omega-6 fatty acids (γ-linoleic acid or arachidonic acid), and experimental studies that evaluated omega-3 fatty acid supplementation (containing predominantly one or more omega-3 fatty acids) on airway and systemic inflammatory markers and/or functional capacity outcomes in people with COPD-related diagnoses. DATA SYNTHESIS: Since statistical pooling was not possible, the findings were presented in narrative form including tables and figures to aid in data presentation when appropriate. RESULTS: One 8-week randomized controlled trial conducted in 80 COPD patients in the Netherlands showed polyunsaturated fatty acid supplementation significantly improved exercise capacity compared with the control condition [between-group difference in mean peak workload was 9.7 W (2.5–17.0; P = 0.009); and mean duration was 4.3 min (0.6–7.9; P = 0.023)]. One cross-sectional study conducted in 250 COPD patients in Spain found associations of specific dietary omega-3 fatty acids with inflammation were inconsistent. CONCLUSIONS: Limited evidence provides weak support for the use of omega-3 fatty acid supplementation for reducing chronic inflammation and some support for improving functional capacity in COPD patients. There is no consistent evidence showing that low dietary intake of specific omega-3 fatty acids worsens inflammation and/or function. More evidence is required before routinely incorporating this therapy within COPD management plans.