Krill Oil Raises EPA and DHA More Than Fish Oil, New Clinical Trial Finds
In what can only be described as fortuitous timing, a Canadian research team recently published their new clinical trial evaluating the effects of a krill oil supplement, in the weeks leading up to Krill Oil Week (yes, there is in fact a week dedicated to krill oil). The randomized controlled clinical trial (RCT) was published in The American Journal of Clinical Nutrition and specifically analyzed the effect of 12 weeks of krill oil supplementation on circulating EPA and DHA, comparing these effects to an equal dose of fish oil.1 The results reported that participants who took the krill oil supplement had a 1.4-fold higher increase in EPA and 1.5-fold higher increase in DHA plasma concentration compared to those taking the fish oil supplement.
The study results prompt a number of follow-up questions, such as what this means for consumers interested in omega-3 supplements, if there are limitations to the study’s report, and how exactly is one expected to celebrate Krill Oil Week? All jokes aside, a discussion about the unique properties of krill is in order, along with a closer look at the recently published study to tease out what its report can tell us about this unique form of omega-3 supplementation.
The Qualities of Krill
Of the many questions which arise regarding omega-3 fatty acid sources, specifically DHA and EPA, perhaps the most common is whether or not there is anything besides fish oil. It comes as a surprise to many when they learn about krill, a small, aquatic crustacean that carries a significant amount of omega-3 within its tissue.
Krill are colorful little creatures who inhabit the world’s oceans and are most prolific in the southern polar waters. Not much longer than a human pinky, these spunky invertebrates accumulate in massive swarms, appearing as rosy-colored clouds gliding in and out of the frigid waters. Speaking of that coloration, krill naturally possess a significant amount of the antioxidant astaxanthin (responsible for krill oil’s red color) as well as the nutrient choline, in addition to their omega-3 content.2 A final key detail about the distinctions of krill is how their omega-3 fats bound in phospholipid form, distinct from the triglyceride form that exists within fish oil. Keep that in mind.
The discovery of krill’s nutrient profile, along with their immense biomass that could sustainably be fished out of the frigid waters, led to the commercialization and sales of the first krill oil supplements at the turn of the 21st century.3 Now we’ve seen an increase in RCTs evaluating the effects of krill oil, and with this latest publication, we can evaluate its effects side by side with fish oil.
Krill Oil Increased Plasma EPA and DHA More Than Fish Oil
The study was a double-blinded (neither researcher nor participant knew who received the treatment) RCT that recruited healthy adults, ages 30-65. They were split into two groups and matched for age and BMI, since both of these factors could influence response to an omega-3 supplement. An additional control measure the researchers employed to boost study rigor was to have the participants record and report intake of fatty fish and marine food, sources of omega-3.
Treatment for this study was simple. For 12 weeks, one group was assigned to take four krill oil capsules per day which provided 1,100 mg/day of omega-3 fatty acids, while the other group also took four fish oil capsules providing a similar amount. Simple as this was, the researchers took painstaking steps to make sure that the amount of EPA and DHA were similar between the two treatment groups. They accomplished this by running a compositional analysis of the fatty acid profile between the fish and krill oil capsules, and confirmed the EPA and DHA content:
“Specifically, the krill oil group received 706 mg EPA and 393 mg DHA, whereas the fish oil group received 738 mg EPA and 462 mg DHA per day.”
When comparing fish and krill oil, there are natural fluctuations both forms possess for specific EPA and DHA content, but here the differences were confirmed to be small enough to not confound the findings. Since the compliance for taking the pills was above 95% in both groups, the researchers could rest assured that any differences between the two groups would be due to differences in the type of omega-3 supplement.
They discovered that participants who took the krill oil saw a sudden and significantly greater increase in blood plasma concentrations of EPA and DHA when compared to the fish oil group. The increase started during the first week of supplementation and plateaued between weeks 4 and 12. At study’s end, krill oil group EPA levels were 1.4 times higher than their fish oil counterparts, and the respective DHA levels 1.5s time higher. So a key question here is what’s different between fish and krill oil that can explain these findings, if the dose of EPA and DHA was relatively similar?
Why Might Krill Oil Raise EPA and DHA More Efficiently?
Here we have arrived at the time to cash in on that key difference between krill and other marine oils. Fats don’t exist in isolation in nature, they are usually esterified (chemically bonded) to a carrier. Krill omega-3 fats are esterified to phospholipids, while fish omega-3s are esterified as triglycerides.
The researchers suggested that this chemical form of bonding for krill oil’s omega-3s likely explains the difference in the absorption and serum concentrations. We can quickly summarize the pathway for triglycerides and phospholipids as follows.
Triglycerides are broken apart, recomposed the same way inside the gut cell, then packed into a chylomicron core for quick delivery to cells. Phospholipids are broken down and integrated back into lipoproteins that then circulate in the blood. Once circulating, they take a long time to be cleared out and appear as elevated levels in the blood, as was reported in the study. Though not a component of the study design, this plausible mechanism of action further strengthens the findings.
Women Had Especially High EPA Responses to Krill Oil
One additional detail reported in the study was the unique effect of krill oil on women. When stratified by sex, EPA concentration increases were the highest among women. At week 12, the EPA increase for the women was significantly higher than men or women in the fish oil group, but it was also higher than the men taking who were also taking krill oil.
It’s not exactly clear why women’s circulating EPA responded more significantly to the krill oil, aside from sex-specific physiology. However, similar results were reported in previous research which observed higher circulating EPA specifically in women after omega-3 supplementation.4
Should You Choose Krill Oil or Fish Oil?
While the results conclusively demonstrate how krill oil effectively elevates serum EPA and DHA significantly more than fish oil, it would be unwise to conclude from this that krill oil is “superior” to fish oil. Krill oil raises EPA and DHA more efficiently and significantly, but fish oil is still a good choice as a bioavailable omega-3 supplement. Krill oil tends to have a higher price, and may require more capsules needed per day, depending on the dose per capsule. Some people may not tolerate fish oil, dislike the larger capsule size, or simply prefer to avoid products which cause “fish oil burps”.
The simple takeaway presented here is that both krill and fish oil effectively raise EPA and DHA, but krill does so more efficiently. If price and tolerance are reasonable tradeoffs for a consumer, that can help settle the matter for which product will be preferred.
These statements have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure, or prevent any disease.
Dustin Moore is a nutrition scientist, dietitian, and public health professional dedicated to advancing evidence-based practice. He holds a PhD in Public Health and is deeply invested in enhancing scientific communication to bridge the gap between the health science and the public.
REFERENCES
- Loukil I, Vachon A, Çaku A, Plourde M. Krill oil increases plasma omega-3 fatty acids more than fish oil in healthy adults: a double-blind randomized controlled trial. The American Journal of Clinical Nutrition. 2026 Jul;124(1):101346. doi:10.1016/j.ajcnut.2026.101346. Read source.
- Sarıyer ET, Baş M, Yüksel M. Comparative Analysis of the Antioxidant and Anti-Inflammatory Effects of Krill and Fish Oil. Int J Mol Sci. 2025 Jul 30;26(15):7360. doi:10.3390/ijms26157360. Read source.
- CCAMLR. Krill fisheries and sustainability | CCAMLR [Internet]. 2018 [cited 2026 Jun 17]. Available from CCAMLR.
- Loukil I, Aguilera EC, Vachon A, Léveillé P, Plourde M. Sex, Body Mass Index, and APOE4 Increase Plasma Phospholipid–Eicosapentaenoic Acid Response During an ω-3 Fatty Acid Supplementation: A Secondary Analysis. J Nutr. 2024 May;154(5):1561–70. doi:10.1016/j.tjnut.2024.03.013. Read source.
