Numerous research trials support the clinical use of the long chain omega-3 polyunsaturated fatty acids, docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), in various conditions and for overall health. Oil from fish, such as sardines and mackerel, has been the main supplemental source of these fatty acids. However, in recent years, krill oil has become a therapeutic agent, found to increase EPA and DHA levels comparable to, or even higher than, fish oil.
Researchers in 2015 compared the oral bioavailability of krill oil with comparable doses of fish oil and found that after 4 weeks, both oils achieved similar total plasma and red blood cell (RBC) levels of EPA and DHA. In the same year, another randomised double-blind study found krill oil significantly increased the plasma phospholipid EPA and DHA levels compared to fish oil and krill meal.
Prior research supports these findings, reporting krill oil intake significantly increased plasma and red blood cell EPA levels, total omega-3 fatty acids and the omega-3 index compared to fish oil.[2,4] A postprandial study conducted in 2011 found that there were higher plasma phospholipid levels of EPA and DHA after krill oil supplementation compared to fish oils and, although the difference was not statistically significant, there was a trend towards increased EPA bioavailability for the krill oil group.[2,5]
Animal studies have also shown significantly increased plasma and phospholipid levels of EPA and DHA with krill oil intake.
Krill oil comes from the algae-feeding shrimp-like crustacean (Euphrasia superba) of the Antarctic. It is rich in EPA and DHA with an estimated ratio of 2:1, compared to fish oil which often has a 1:1 ratio.[2,3] Another difference to fish oil is its structure. Krill oil contains a major part (30-65%) of the EPA and DHA as phospholipids (PLs), specifically phosphatidylcholine, whereas the fatty acids in fish oil are mainly stored as triglycerides. This structural difference may increase the absorption and tissue deposition of fatty acids from krill oil.[2,6]
Because PLs form the structure of cell membranes, long-chain omega-3 polyunsaturated fatty acids, in the form of PLs, might facilitate the passage of fatty acids through the intestinal wall and increase the bioavailability of these fatty acids in krill oil.
- Yurko-Mauro K, Kralovec J, Bailey-Hall E, et al. Similar eicosapentaenoic acid and docosahexaenoic acid plasma levels achieved with fish oil or krill oil in a randomized double-blind four-week bioavailability study. Lipids Health Dis 2015;14:99. [Full Text]
- Ulven SM, Holven KB. Comparison of bioavailability of krill oil versus fish oil and health effect. Vasc Health Risk Manag 2015;11:511-524. [Full Text]
- Kohler A, Sarkkinen E, Tapola N, et al. Bioavailability of fatty acids from krill oil, krill meal and fish oil in healthy subjects--a randomized, single- dose, cross-over trial. Lipids Health Dis 2015;14:19. [Full Text]
- Ramprasath VR, Eyal I, Zchut S, et al. Enhanced increase of omega-3 index in healthy individuals with response to 4-week n-3 fatty acid supplementation from krill oil versus fish oil. Lipids Health Dis. 2013;12:178. [Full Text]
- Schuchardt JP, Schneider I, Meyer H, et al. Incorporation of EPA and DHA into plasma phospholipids in response to different omega-3 fatty acid formulations--a comparative bioavailability study of fish oil vs Krill oil. Lipids Health Dis 2011;10:145. [Full Text]
- Ghasemifard S, Hermon K, Turchini GM, et al. Metabolic fate (absorption, beta-oxidation and deposition) of long-chain n-3 fatty acids is affected by sex and by the oil source (krill oil or fish oil) in the rat. Br J Nutr 2015;114(5):684-692 [Full Text]