Does krill oil contain more effective Omega-3 EPA and DHA than fish oil?

Omega-3s in krill oil are better absorbed than those in fish oil; indicating this are studies that have measured their levels in the blood and integration into red blood cell membranes following supplementation. But are they also more effective? Let's find out!

EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) are the two bioactive Omega 3s-the ones we need to harness the benefits of these health-allied fats.

We can take them preformed from sources of marine origin. The best known of these are undoubtedly fish and the oils derived from them (fish oil and cod liver oil); in recent years, however, krill oil obtainable from a tiny crustacean that lives in the cold waters of the South Seas is also becoming increasingly popular: antarctic krill (Euphausia superba).

Krill is the main component of the zooplankton biomass found in Antarctic waters. Given the intense exploitation of marine fish populations, the possibility of using it as an alternative raw material for the production of Omega 3 supplements is very attractive.

What's more, within krill oil, Omega 3s are present in the form of phospholipids-the main components of cell membranes into which Omega 3s fit to exert their benefits.

In natural fish oil, however, EPA and DHA are present in the form of triglycerides. During the production of Omega 3 supplements, this natural fish oil undergoes purification and concentration processes that mean that EPA and DHA may be present in the product that is put on the market in the form of ethyl esters (different molecules than those originally found in fish oil) or re-esterified triglycerides (more concentrated in Omega 3 than in natural fish oil, but chemically similar).

Omega-3 from krill and fish: do differences in chemical form affect bioavailability?

Research over the years has led to the hypothesis that these differences at the chemical level between krill and fish Omega-3s correspond to a higher bioavailability of krill oil's EPA and DHA, that is, that they are better absorbed.

Back in 2009, a group of researchers led by Kevin Maki of the U.S.-based Provident Clinical Research focused on this issue, comparing the levels of EPA and DHA in the blood of 76 individuals (men and women with excess weight) who had consumed 2 grams per day of krill, fish or olive oil for 4 weeks.

"Significant increases over baseline levels of EPA and DHA in the blood were observed with krill oil supplementation," explained Maki and colleagues. In the case of krill oil, the average increase was 178.4 +/- 38.7 µmol/L for EPA and 90.2 +/- 40.3 µmol/L for DHA; in the case of fish oil, however, the average increase was 131.8 +/- 28.0 µmol/L for EPA and 149.9 +/- 30.4 µmol/L for DHA.

Returning to the topic in 2010, a team of researchers led by Stine Ulven of Akershus University College in Lillestrøm, Norway, found a similar increase in plasma EPA and DHA levels following intake of krill oil and fish oil "although," the researchers pointed out, "the dose of EPA+DHA in krill oil was 62.8 percent of that in fish oil."

As pointed out by Ulven and colleagues, "these results indicate that Omega 3 polyunsaturated fatty acids from krill oil (mainly phospholipids) are equally, or even more, bioavailable than those from fish oil (triglycerides)."

By equalizing the dosage of Omega 3 received with fish oil and with krill oil, Jan Philipp Schuchardt and colleagues from the University of Hanover, Germany, were able to eliminate possible doubts, confirming that taking krill oil can result in a greater increase in EPA+DHA levels in plasma phospholipids.

Finally, a study conducted in Canada by researchers at the Centre for Functional Foods and Nutraceuticals in Winnipeg unveiled that krill oil also increases more effectively than fish oil theOmega-3 Index (Omega-3 Index), that is, the percentage of EPA and DHA out of the total fatty acids in red blood cell membranes.

As mentioned, one of the biological functions of EPA and DHA is to become part of cell membranes, to which they impart the fluidity necessary for various activities of the cell. The Omega 3 Index value (thus the level of Omega 3 in red blood cell membranes) is inversely proportional to the risk of cardiovascular problems, and the Canadian research, published in the journal Lipids in Health Disease, was a further contribution to the debate on the positive effects of krill oil.

The latter study recruited 24 healthy volunteers who participated in a trial organized in 3 different phases, each of 4 weeks, interspersed with an 8-week period. The volunteers, randomly divided into 3 groups, took 6 capsules per day containing krill oil, fish oil, or corn oil (placebo) during treatment.

In the first phase, one group took krill oil, one the fish oil, and one the placebo; after 4 weeks of treatment and an 8-week interval, each group received a different type of capsule for 28 days, and so on so that each received supplementation with the two types of oil and the placebo.

The Omega-3 content in the plasma and red blood cells of each volunteer was analyzed before and after each phase. After each phase, a greater increase in the level of Omega-3 in plasma and red blood cells was found in the subjects who had received the krill oil or fish oil supplements. Between the two, however, a difference mersed: in fact, the change in Omega-3 Index after consumption of krill oil and fish oil was 1.04% and 0.47%, respectively.

In addition, there was a reduction in the concentration of Omega-6 (polyunsaturated fats that tend to be more inflammatory than Omega-3) in volunteers who had received these supplements. Specifically, in those who had taken krill oil, the increase in Omega-3 and reduction in Omega-6 was greater than that found in those who had taken fish oil.

The probable role of phospholipid structure and free fatty acids 

Scientists hypothesize that due to the phospholipid structure, krill Omega-3s may be more easily absorbed and integrated into cell membranes than those found in fish oil triglycerides.

In addition, when analyzing the structure of fats in the supplements used in their study, Schuchardt and colleagues found the presence of a substantial proportion of EPA and DHA (22 and 21 percent, respectively) in the free fatty acid form, which was absent in fish oil. This, the researchers explain, "could significantly influence the bioavailability of EPA and DHA from krill oil."

Only further studies will help prove this point and clarify the mechanism behind the improved absorption of fats in this source of Omega 3.

Is krill oil more effective than fish oil?

Data collected during these trials suggest that krill oil supplements may exert a better protective effect against cardiovascular disease than fish oil supplements.

This aspect has been explored in some of this and other research. In 2015, Ulven tried to take stock of the situation together with Kirsten Holven of the University of Oslo (Norway). Writing in the pages of Vascular Health and Risk Management, the two experts concluded that "krill oil regulates more metabolic pathways than fish oil" and that this "might indicate different biological effects of krill oil compared to fish oil."

A few years later, a group of Korean researchers analyzed the available evidence on the effects of these two marine-derived oils on blood fat levels. "The net differences in triglycerides, LDL cholesterol, HDL cholesterol, and total cholesterol were not significant," the experts explained in the pages of Nutrition Reviews, concluding that "the effects of krill oil and fish oil on lipids (i.e., blood cholesterol and triglycerides, ed.) are not different" and that "the reduction in triglycerides," which is one of the main reasons why EPA and DHA supplements are prescribed, "depends on the dose of omega-3 fatty acids taken."

Krill oil: a viable and safe alternative to fish oil

Based on the available data, it is possible to reasonably conclude that krill oil is a viable alternative to fish oil. Its intake has not been associated with any worrisome side effects; therefore, the only absolute contraindication remains, at least for the time being, shellfish allergy.

It is worth mentioning that in addition to EPA and DHA, krill oil also contains a powerful natural antioxidant (astaxanthin) and choline, a molecule allied to the heart and liver. Find out all its features by reading this in-depth article: Krill oil, all the benefits and properties.

Bibliographic references:

European Community. Food and Feed Information Portal Database. Last viewed: 24/04/25

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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 Sep;29(9):609-15. doi: 10.1016/j.nutres.2009.09.004

Ramprasath VR, Eyal I, Zchut S, Jones PJ. 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 Dec 5;12:178. doi: 10.1186/1476-511X-12-178

Schuchardt JP, Schneider I, Meyer H, Neubronner J, von Schacky C, Hahn A. 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 Aug 22;10:145. doi: 10.1186/1476-511X-10-145

Ulven SM, Holven KB. Comparison of bioavailability of krill oil versus fish oil and health effect. Vasc Health Risk Manag. 2015 Aug 28;11:511-24. doi: 10.2147/VHRM.S85165

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. Lipids. 2011 Jan;46(1):37-46. doi: 10.1007/s11745-010-3490-4