Fish and krill oil could reduce the levels of cardiovascular risk factors. However, the PhD thesis of Amanda Rundblad indicates that the quality of fish oil is important for the effect.


  1. High-quality fish oil has a more favourable effect on specific lipoproteins compared to oxidised fish oil.

  2. Both krill oil and recommended consumption of fish have benefitial effects on cardiovascular risk factors.
  3. Krill oil supplementation alters the expression of several genes related to glucose and cholesterol metabolism.


Thesis: Marine omega-3 fatty acids from different dietary sources and effects on cardiovascular risk markers
Candidate: Amanda Rundblad
Time: June 4, 2018 at 14:45
Place: Oslo Metropolitan University, Pilestredet 44: Auditorium V130
Link to university website (in Norwegian)


(1) High-quality fish oil reduced the concentration of intermediate-density lipoprotein particles and large, medium and small low-density liporotein particles more than oxidised fish oil and high-oleic sunflower oil. The concentrations of total lipids, phospholipids, total cholesterol, cholesteryl esters and free cholesterol in these lipoprotein subclasses were also reduced more with the high-quality fish oil.

54 participants received either high-quality fish oil, oxdised fish oil or high-oleic sunflower oil capsules for seven weeks. Lipoprotein subclasses were analysed by nuclear magnetic resonance spectroscopy.

(2) Omega-3 fatty acids from fish or krill oil did not reduce triglyceride leves in healthy subjects. However, krill oil reduced blood glucose, and regular intake of fish increased D vitamin levels compared to sunflower oil.

The randomised study compared krill oil supplementation with the intake of fish with similar amounts of omega-3 fatty acids. 36 healthy subjects received either fish according to dietary guidelines, krill oil or sunflower oil for eight weeks.

(3) The mRNA expression of four genes were differently altered by krill oil, fish and sunflower oil. Moreover, within-group analyses showed that krill oil reduced the expression of 13 genes, many of which are involved in glucose and cholesterol metabolism. Sunflower oil reduced several genes related to inflammation, but there were no between-group differences in circulating inflammatory markers.


(1) Rundblad, A., Holven, K. B., Ottestad, I., Myhrstad, M. C., & Ulven, S. M. (2017). High-quality fish oil has a more favourable effect than oxidised fish oil on intermediate-density lipoprotein and LDL subclasses: a randomised controlled trialBritish Journal of Nutrition117(9), 1291-1298.

(2) Rundblad, A., Holven, K. B., Bruheim, I., Myhrstad, M. C., & Ulven, S. M. (2018). Effects of krill oil and lean and fatty fish on cardiovascular risk markers: a randomised controlled trialJournal of Nutritional Science7.

(3) Rundblad, A., Holven, K. B., Bruheim, I., Myhrstad, M. C., & Ulven, S. M. (2018). Effects of fish and krill oil on gene expression in peripheral blood mononuclear cells and circulating markers of inflammation: a randomised controlled trialJournal of nutritional science7.

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