Plain language summary
Intake of omega 3 fatty acids is associated with a reduction in cardiovascular disease (CVD) risk. Krill oil is a source of omega-3 fatty acids that has been shown to modulate gene expression in animal studies. The aim of this 8 week randomised controlled trial was to investigate the effect of fish intake and krill oil on the expression of genes related to lipid and glucose metabolism and inflammation. Thirty-six healthy adults were split into three groups. The krill group took capsules containing 4g of krill oil per day. The fish group ate fish three times a week, and the control group were given high-oleic sunflower oil (HOSO) with added astaxanthin. Blood samples were analysed for gene expression and markers of inflammation and endothelial dysfunction at the start and end of the study. Intake of krill oil significantly down-regulated the expression of 13 of the 40 genes that were analysed, including genes involved in glucose and cholesterol metabolism and fatty acid beta-oxidation. Intake of fish significantly altered the expression of just four of the genes. Intake of HOSO with added astaxanthin significantly reduced the expression of 16 genes involved in inflammation and cholesterol transport. There were no significant changes in markers of inflammation and endothelial dysfunction across the three groups, possibly due to the relatively low dose of omega-3 fatty acids given. The authors suggest that the higher levels of eicosapentaenoic acid (EPA) in krill oil compared to fish could be partly responsible for the increased beneficial effects. Monounsaturated fatty acids (MUFAs) and astaxanthin (found naturally in krill oil) may also have contributed to the findings. Further studies are needed to understand the effects of fatty acids on gene expression.
Abstract
Marine n-3 (omega-3) fatty acids alter gene expression by regulating the activity of transcription factors. Krill oil is a source of marine n-3 fatty acids that has been shown to modulate gene expression in animal studies; however, the effect in humans is not known. Hence, we aimed to compare the effect of intake of krill oil, lean and fatty fish with a similar content of n-3 fatty acids, and high-oleic sunflower oil (HOSO) with added astaxanthin on the expression of genes involved in glucose and lipid metabolism and inflammation in peripheral blood mononuclear cells (PBMC) as well as circulating inflammatory markers. In an 8-week trial, healthy men and women aged 18-70 years with fasting TAG of 1·3-4·0 mmol/l were randomised to receive krill oil capsules (n 12), HOSO capsules (n 12) or lean and fatty fish (n 12). The weekly intakes of marine n-3 fatty acids from the interventions were 4654, 0 and 4103 mg, respectively. The mRNA expression of four genes, PPAR γ coactivator 1A (PPARGC1A), steaoryl-CoA desaturase (SCD), ATP binding cassette A1 (ABCA1) and cluster of differentiation 40 (CD40), were differently altered by the interventions. Furthermore, within-group analyses revealed that krill oil down-regulated the mRNA expression of thirteen genes, including genes involved in glucose and cholesterol metabolism and β-oxidation. Fish altered the mRNA expression of four genes and HOSO down-regulated sixteen genes, including several inflammation-related genes. There were no differences between the groups in circulating inflammatory markers after the intervention. In conclusion, the intake of krill oil and HOSO with added astaxanthin alter the PBMC mRNA expression of more genes than the intake of fish.
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