Replacing fish oil with vegetable oils in salmon feed increases hepatic lipid accumulation and reduces insulin sensitivity in mice

Background: To ensure sustainable aquaculture, fish derived raw materials are replaced by vegetable ingredients. Fatty acidcomposition and contaminant status of farmed Atlantic salmon (Salmo salar L.) are affected by the use of plant ingredientsand a spillover effect on consumers is thus expected. Here we aimed to compare the effects of intake of Atlantic salmon fedfish oil (FO) with intake of Atlantic salmon fed a high proportion of vegetable oils (VOs) on development of insulin resistanceand obesity in mice. Methodology/principal findings: Atlantic salmon were fed diets where FO was partly (80%) replaced with three differentVOs; rapeseed oil (RO), olive oil (OO) or soy bean oil (SO). Fillets from Atlantic salmon were subsequently used to prepareWestern diets (WD) for a mouse feeding trial. Partial replacement of FO with VOs reduced the levels of polychlorinatedbiphenyls (PCB) and dichloro-diphenyl-tricloroethanes (DDT) with more than 50% in salmon fillets, in WDs containing thefillets, and in white adipose tissue from mice consuming the WDs. Replacement with VOs, SO in particular, lowered the n23polyunsaturated fatty acid (PUFA) content and increased n26 PUFA levels in the salmon fillets, in the prepared WDs, and inred blood cells collected from mice consuming the WDs. Replacing FO with VO did not influence obesity development inthe mice, but replacement of FO with RO improved glucose tolerance. Compared with WD-FO fed mice, feeding mice WD-SO containing lower PCB and DDT levels but high levels of linoleic acid (LA), exaggerated insulin resistance and increasedaccumulation of fat in the liver. Conclusion/Significance: Replacement of FO with VOs in aqua feed for farmed salmon had markedly different spillovereffects on metabolism in mice. Our results suggest that the content of LA in VOs may be a matter of concern that warrantsfurther investigation. Citation: Midtbø LK, Ibrahim MM, Myrmel LS, Aune UL, Alvheim AR, et al. (2013) Intake of Farmed Atlantic Salmon Fed Soybean Oil Increases Insulin Resistanceand Hepatic Lipid Accumulation in Mice. PLoS ONE 8(1): e53094. doi:10.1371/journal.pone.0053094Editor: Frances M. Sladek, Univeristy of California Riverside, United States of AmericaReceived June 22, 2012; Accepted November 27, 2012; Published January 2, 2013Copyright: 2013 Midtbø et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permitsunrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Funding: This study was funded by the Research Council of Norway, project 199626. The funders had no role in study design, data collection, decision to publishor preparation of the manuscript.Competing Interests: Grete Rosenlund is funded by Skretting Aquaculture Research Centre (ARC). Skretting ARC’s role was to produce the salmon for thefeeding trial with a fatty acid composition tailored according to the study design. This does not alter the authors’ adherence to all the PLOS ONE policies onsharing data and materials.* E-mail: [email protected] (LM); [email protected] (KK). These authors contributed equally to this work.