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Chronic obstructive pulmonary disease (COPD) is a progressive disease of the airways, underpinned by inflammation and worsening lung function. Omega-3 polyunsaturated fatty acids (n-3PUFA) can modulate inflammatory mechanisms and may therefore impact lung function in people with COPD. This observational, cross-sectional study of 577 adults in the Whyalla Intergenerational Study of Health (WISH), conducted during 2008–09 in regional South Australia, explored associations between fish and PUFA intakes (from food frequency questionnaires) and lung function (spirometry). It also included a nested case-control study which compared fish and PUFA intakes and plasma phospholipid PUFA levels between 40 people with COPD and 80 age-sex matched controls. In the whole population, linear regression models adjusted for age, sex, smoking status and education demonstrated a weak negative association between lung function (FEV1% predicted) and consumption of fried fish (OR -0.12, 95% CI -0.22, −0.01, P = 0.026) but not fish prepared by other cooking methods or estimated intakes of PUFA. There was no association between fish or PUFA intakes and COPD risk. Compared to age and sex matched controls, cases had poorer lung function and a higher rate of smoking prevalence but did not differ in their intakes of fish or PUFA or their PUFA levels in plasma phospholipids. In this sub-population, we found a marginally significant association between COPD risk and total long chain n-3PUFA levels in plasma phospholipids (OR 1.22 95% CI 1.00–1.49, P = 0.046). Given the relatively small number of cases in this analysis, this finding should be interpreted with caution, especially given the lack of association with other markers of n-3PUFA intake or status. Taken together, our data suggest that n-3PUFA intake and status are not determinants of improved lung function in this regional Australian population. Keywords: Lung function, Chronic obstructive pulmonary disease, COPD, Polyunsaturated fatty acid, PUFA

Context: The anti-inflammatory activity of long-chain n-3 polyunsaturated fatty acids (PUFAs) has been established in several chronic inflammatory diseases but has yet to be demonstrated in inflammatory lung diseases such as chronic obstructive pulmonary disease (COPD). Objective: The aim of this systematic review was to investigate, using PRISMA guidelines, the relationship between the intake of long-chain n-3 PUFAs and the prevalence, severity, and health outcomes of COPD. Data Sources: Eight health databases and the World Health Organization’s international clinical trial registry were searched for relevant studies. Study Selection: Experimental or observational studies that were published in English and that assessed long-chain n-3 PUFA intake (by determining habitual consumption and/or tissue levels) in adults with COPD were included. Data Extraction: Publication demographics, participant characteristics, type of intervention or exposure, long-chain n-3 PUFA intake, pulmonary function, COPD mortality, and COPD severity were independently extracted from each article by 2 authors using a prospectively designed data extraction tool. Data Synthesis: All 11 of the studies included in the review were observational. Approximately equal numbers of studies reported significant (n = 6, 5 inverse) relationships or no significant relationships (n = 5) between either consumption of long-chain n-3 PUFAs or levels of long-chain n-3 PUFAS in tissue and a COPD outcome. Conclusions: Current evidence of a relationship between long-chain n-3 PUFA intake and COPD is limited and conflicting, with studies having wide methodological variation. Registration number: PROSPERO 2013:CRD42013004085

Scientific articles are retracted infrequently, yet have the potential to influence the scientific literature for years. The only randomised controlled trial to explore the effects of omega-3 polyunsaturated fatty acids in people with chronic obstructive pulmonary disease was retracted in 2008 due to falsified data. The objective of this research was to determine the frequency and nature of citations of this retracted paper. Web of Science and Google Scholar were used to determine the number of times the retracted article was cited. Citations were classified as either “retraction acknowledged” or “retraction not acknowledged”. The search was conducted on 6 August 2013 and updated on 25 March 2014. Results: The search resulted in 76 citations, of which 24 occurred prior to the retraction of the article. Of the 52 citations occurring after the retraction, only two acknowledged the retraction. Of the citations not acknowledging the retraction, 20 referred to specific data and 30 cited the reference in passing. This retracted article continues to be cited by authors, suggesting that information about the retraction was unsuccessfully communicated to the scientific community. Continual citation of retracted literature has the potential to bias a field of research and potentially misinform end-users. Refereed/Peer-reviewed

Background Long-chain omega-3 polyunsaturated fatty acids (LCn-3PUFAs) may act as an effective adjunct therapy for chronic obstructive pulmonary disease (COPD), a condition characterised by persistent airflow limitation and inflammation. However, the nature of this illness presents challenges for evaluating potential benefits. The aim of this study was to determine the feasibility of undertaking a randomised controlled trial of LCn-3PUFA supplementation in adults with COPD. Methods A 16-week parallel, double-blind, randomised, placebo-controlled dietary supplementation trial was conducted. Participants diagnosed with COPD were randomly allocated to take six 1-g capsules of fish oil (3.6 g LCn-3PUFA) or corn oil (placebo) daily for 16 weeks. Key outcomes used to determine the feasibility of the trial included recruitment rate, participant retention rate and supplement adherence (blood biomarker and returned capsule count). An estimate of the effect size for clinical outcomes such as pulmonary function and functional exercise capacity was calculated. Results None of the key feasibility criteria were met. The enrolment target was 40 participants in 52 weeks; however, only 13 were finally enrolled, with just seven in the first 52 weeks. Eight participants completed the study (retention rate 62%). Targets for compliance were not achieved; red blood cell LCn-3PUFA content (expressed as percentage of total fatty acids) did not increase by more than 2% in the fish oil group; capsule counts were unreliable. As the target sample size was not achieved and only a small number of participants completed the study, it was not possible to use the variance in clinical outcomes to estimate a sample size for a future study. Conclusions This study highlights major difficulties, especially with recruitment, in conducting this LCn-3PUFA supplementation trial in people with COPD, rendering the protocol unfeasible by predetermined criteria. A modified approach is needed to investigate potential health benefits of fish oil in people with COPD. A multicentre study with changes to inclusion and exclusion criteria is recommended. Trial registration Australia and New Zealand Clinical Trials Register (ANZCTR), ACTRN12612000158864 Electronic supplementary material The online version of this article (10.1186/s40814-017-0211-2) contains supplementary material, which is available to authorized users.

There is evidence to support the use of supplementation with long-chain omega-3 polyunsaturated fatty acids (LCn-3PUFA) from oily fish or fish oil for the treatment of various inflammatory diseases such as rheumatoid arthritis. Chronic obstructive pulmonary disease (COPD) is a progressive, terminal disease characterized by persistent airflow limitation, lung and systemic inflammation. To date, one randomized controlled trial has been published that assessed the efficacy of LCn-3PUFA in people with this condition. The aim of this article is to discuss the feasibility of conducting a trial to evaluate fish oil supplementation as adjunct therapy in people with COPD., The study is supported by a University of South Australia, Division of Health Sciences grant (DRDG 2011 (round 2)).