Within the omega-3 category, there are some important differences between sources that can impact the delivery of these fatty acids to the body’s cells and tissues. In particular, krill oil’s omega-3s are mostly bound to phospholipids and therefore undergo different digestive and distribution routes vs. fish oil when they get into the body.
Because phospholipids are integral parts of cell membranes, krill’s omega-3s exhibit preferential uptake in the cells. Fish oil’s omega-3s on the other hand must be converted in the liver before they are available to the body’s cells. The increased cellular uptake has strong implications for omega-3s’ deposition in important tissues and organs such as the brain and heart.
Here’s a look at a couple comparison studies
Study: Performed by Kevin C. Maki and co-workers at the Provident Clinical Research, in Bloomington, IN, and the Meridien Research Centers, in St. Petersburg, FL, this study was set up as a randomized, double-blind parallel arm trial. Within this setup, 76 overweight and obese men and women were randomly distributed into three groups to take Superba™ Krill Oil, fish oil, or olive oil for four weeks. To avoid any influence, the supplementation given was unknown to both the study subjects and researchers.
Results: While the received daily amount of EPA was similar in the krill oil and fish oil groups, the DHA quantity was approximately half as much in the krill oil group compared to the fish oil group. Nevertheless, at the end of the study period, plasma analysis showed that the mean EPA concentrations were higher in the krill oil group compared to the fish oil group, and the mean DHA concentrations were similar in both groups. Both sources of omega-3 fatty acids were safe and well-tolerated.
Most importantly, krill oil supplementation (2g/d) resulted in increased plasma EPA bioavailability and revealed equal bioavailability in the case of DHA, but at half the dosage in comparison to fish oil. Overall, after dose adjustment, researchers noted that the total increase of EPA and DHA in the plasma of the subjects who received Superba™ Krill Oil for 4 weeks was 24% higher than that of the subjects who received fish oil.
Citation: Maki KC, Reeves MS, Farmer M, Griinari M, Berge K, Vik H, Hubacher R, Rains TM: Krill oil supplementation increases plasma concentrations of eicosapentaenoic and docosahexaenoic acids in overweight and obese men and women. Nutr Res 2009, 29(9):609-615.
Study: Performed by researchers at Akershus University College and University of Oslo, Norway, this study investigated if a lower dose of EPA and DHA provided in phospholipids compared to omega-3 fatty acids provided in triglycerides had equal bioavailability of these fatty acids in plasma. One hundred and thirteen subjects with normal or slightly increased total blood cholesterol and/or triglyceride levels were randomized into three groups and given Superba™ Krill Oil, fish oil, or placebo for seven weeks. The daily supplementation of total EPA and DHA was approximately 37% less in the krill oil group than in the fish oil group.
Results: The results showed that dietary omega-3 administration led to a similar increase of plasma omega-3 fatty acids in both the krill and fish oil groups compared to the control group. These findings suggest that a lower dosage of EPA and DHA in phospholipid form is required to obtain plasma EPA and DHA levels comparable to the triglyceride form of omega-3 supplementation.
After adjustment of EPA and DHA levels to the daily dose given, the results from the krill oil group suggest a 45% higher total EPA and DHA plasma level than in the fish oil group after 7 weeks of administration.
Citation: Ulven SM, Kirkhus B, Lamglait A, Basu S, Elind E, Haider T, Berge K, Vik H, Pedersen JI: Metabolic Effects of Krill Oil are Essentially Similar to Those of Fish Oil but at Lower Dose of EPA and DHA, in Healthy Volunteers.Lipids2011, 46(1):37-46.
While these studies are highly interesting, more work is needed to compare blood levels of omega-3s from both sources. Future studies evaluating the effects of these two sources on the Omega-3 Index will help further elucidate how krill oil and fish oil compare to one another. In the meantime, both krill oil and fish oil are noted by researchers to be valuable sources of EPA and DHA omega-3s.