Carried out alongside The Netherlands Organization for Applied Scientific Research (TNO), the team points to the oil’s ability to reduce disease-promoting lipids and obesity-related inflammation as well as helping to reduce insulin resistance.
“Krill oil treatment increased the concentrations of eicosapentaenoic acid and docosahexaenoic acid (EPA and DHA) and associated oxylipins,” the research team writes. “Simultaneously, KrO decreased arachidonic acid concentrations and arachidonic-acid-derived oxylipins.”
“In the liver, krill oil suppressed inflammatory signalling pathways without affecting liver histology.”
Together with colleagues from the Leiden University Medical Center, the researchers enrolled mice into the Krill Oil (KrO) treatment group, where they were fed on a High Fat Diet (HFD) in which 3% of the total diet was replaced with KrO (KrO diet).
The KrO (Superba Boost, Aker BioMarine) itself contained EPA (over 150 milligrams per gram (mg/g)) and DHA (over70 mg/g), which is approximately 20% of EPA and DHA fatty acids in KrO.
Meanwhile the control group (sample size - 15) was treated with an energy-dense high-fat diet (20 kcal% protein, 35 kcal% carbohydrate, 45 kcal% fat, with 39 kcal% from lard and 6 kcal% from soybean oil).
At an expected average daily intake of three grams (g) diet per mouse, the dietary intake of KrO was 0.09 g/mouse/day on average.
Analyses of cholesterol, triglycerides, insulin, blood glucose and other measurements were taken after eight weeks, 16 weeks and 28 weeks.
Findings revealed that KrO treatment affected the lipid composition in the circulation, white adipose tissue (eWAT) and the liver in a comparable way.
All tissues showed a marked increase in omega-3 Fatty Acids (FAs) and a decrease in arachidonic acid (ARA) concentrations. The highest absolute concentrations of omega-3 FAs were observed in the liver.
Further team findings suggested KrO prevented the activation of inflammatory regulators and stimulated the formation of anti-inflammatory bioactive lipids.
Experiments that looked into the effects of krill oil in the liver found KrO quenched inflammatory signalling pathways and upregulated the expression of proteins that interfere with NF-κB signalling – an immune-related pathway involved in inflammation.
The oil also suppressed the accumulation of lipids and oxylipins that promote inflammation and strongly induced the presence of lipid species that contribute to an anti-inflammatory effect.
“We have demonstrated that long-term KrO treatment (28 w) improves the fatty acid composition in the circulation, WAT and the liver,” the team writes.
“This improvement is characterised by marked elevations in omega-3 FAs and associated oxylipins, which can exert beneficial effects on metabolism (e.g., fasting insulin, adipokines) and tissue inflammation.“
Krill oil health benefits
KrO, a marine oil extracted from Antarctic krill, has a high content of long-chain omega-3 polyunsaturated fatty acids (PUFAs), in particular EPA and DHA.
Lipids from KrO can be stored in cells or converted intracellularly into a variety of bioactive oxylipins that can act as direct inflammatory modulators.
Many of the fatty acids (FAs) present in KrO, as well as their metabolites, are ligands of transcriptional regulators, including peroxisome-proliferator-activated receptors (PPARs).
Besides being a ligand for PPARs, KrO-derived EPA and DHA can displace ARA, an omega-6 FA with proinflammatory properties, from membranes and may also compete with ARA for further enzymatic processing.
Via these indirect mechanisms, EPA and DHA can attenuate the pro-inflammatory effects of ARA and its downstream metabolites.
Furthermore, EPA and DHA themselves can be enzymatically converted into inflammation-resolving mediators, including hydroxyeicosapentaenoic acids (HEPEs), hydroxy docosahexaenoic acids (HDHAs) and further into resolvins (RVs), protectins (PDs) and maresins (MaRs).
Published online: doi.org/10.3390/nu13082836
“Krill Oil Treatment Increases Distinct PUFAs and Oxylipins in Adipose Tissue and Liver and Attenuates Obesity-Associated Inflammation via Direct and Indirect Mechanisms.”
Authors: Eveline Gart et al