Results of the small study, published in Nutrients, indicated that 30 days of krill oil [KO] supplementation led to a 35.6% higher EPA levels in the lipidome compared to fish oil [FO].
However, there were no differences between the groups for DHA, DPA, total long-chain omega-3 polyunsaturated fatty acids (PUFA), arachidonic acid, linoleic acid, or alpha-linolenic acid, reported scientists from Victoria University, Deakin University, Monash University and the Baker Heart and Diabetes Institute.
The study focused on the lipidome, the complex collection of all lipid species in an organism.
“Use of lipidomics enabled the first clear observation of differentiation between the plasma lipid molecular species influenced by KO and FO consumption at steady state (that is, after 30 days of supplementation),” wrote the scientists.
“This strongly suggests that the different lipid classes present in the supplements (>40% PC [phosphatidylcholine] species for KO and >99% TG [triglycerides] and DG [diglycerides] for FO) have a sustained influence on the lipid molecular species in plasma.
“KO had a significantly greater increase in 27 different lipid molecular species in seven phospholipid classes. In contrast, FO treatment showed significant effects on 17 separate lipid molecular species from four phospholipid classes (two of which were different to those influenced by KO).”
The researchers said that the physiological ramifications of these differences are unknown, “but they highlight that future studies on KO and FO comparisons should look beyond the omega 3 fatty acids”.
“A nice start”
Commenting independently on the study, Dr William Harris, PhD, from the University of South Dakota told and a principal in the omega-3s testing firm OmegaQuant, called the study, “a nice start”.
“The lipidome is much more complex than just the fatty acids,” he explained. “Cholesterol is part of the lipidome, every triglyceride and phospholipid is part of the lipidome.
“This study is a nice start but it would have been unexpected had krill and fish oil had the same effect on the lipidome,” said Dr Harris.
“This study lays a foundation for future research around the biological, physiological, and clinical significance of the individual forms.”
The researchers recruited 11 women aged between 18 and 50 to participate in their randomized, cross-over study. The women were randomly assigned to receive either supplements of fish oil (Natural FO, Swisse Wellness) or krill oil (Euphausia superba oil, Swisse Wellness) for 30 days. This was followed by a four week “washout” period and they then crossed over to the other intervention. The fish oil and krill oil supplements provided EPA doses of 786 mg/day and 759 mg/day, respectively, and DHA doses of 470 mg/day and 420 mg/day, respectively.
Results showed the relAUC or relative area under the curve for EPA was 23.9% higher at day 15 for the krill oil supplementation, and this increased to 35.6% higher at day 30, compared to the fish oil group.
The researchers also found that krill oil supplementation had modestly increased cholesterol levels and lower phosphatidylserine (PS) level.
“This study shows that KO and FO do not have equivalent effects on the plasma lipidome,” they wrote.
“Plasma EPA was significantly greater following KO treatment in contrast to the FO treatment. Significant remodelling of the plasma lipidome was observed between KO and FO treatments, with a clear differentiation in their effects on different plasma lipid molecular species, with the changes in lipid species not restricted to those enriched in omega-3 PUFA.
“Further studies will be needed to determine whether the differences seen here have biological consequences/health benefits.”
The study was funded by the College of Health and Biomedicine, Victoria University, and the Operational Infrastructure Support Scheme of the Victorian State Government.
2020, 12(9), 2804; doi: 10.3390/nu12092804
“Krill Oil Has Different Effects on the Plasma Lipidome Compared with Fish Oil Following 30 Days of Supplementation in Healthy Women: A Randomized Controlled and Crossover Study”
Authors: P.J. Meikle, et al.