The two most common omega-3 sources look nearly identical on a supplement label — but new research shows the body doesn't use them the same way.

What to know:
• A 2026 double-blind randomized trial found krill oil raised blood EPA levels 1.4x and DHA levels 1.5x more than fish oil, at a matched dose.
• The difference comes down to delivery form: krill's omega-3s are bound to phospholipids — the same molecule human cell membranes are made of. Fish oil's are bound to triglycerides, a different molecule entirely.
• Multiple independent studies, using different research groups and different fish oil comparators, keep finding the same pattern.

If you've ever compared omega-3 supplement labels side by side, you've probably done the obvious thing: checked the EPA and DHA milligram counts and assumed the higher number wins. It's a reasonable assumption. It's also, according to a growing body of clinical research, an incomplete one.

Same Nutrient, Different Delivery System

Both krill oil and fish oil supply the same two headline omega-3s: EPA and DHA. What differs is the molecular “packaging” each one arrives in.

In fish oil, EPA and DHA are bound to triglycerides — the same class of molecule your body uses to store energy as fat. In krill oil, they're bound to phospholipids — a structurally different molecule that happens to be the primary building block of every cell membrane in the human body, including the membranes of red blood cells, neurons, and the cells lining the heart.

That structural overlap is not a coincidence researchers have simply noted in passing. It's become the leading explanation for why krill oil's omega-3s seem to move more efficiently from the digestive tract into the bloodstream and, from there, into tissue.

The clearest recent evidence comes from a 2026 double-blind, randomized controlled trial published in the American Journal of Clinical Nutrition. Seventy-two healthy adults were split into two groups — one taking krill oil, one taking fish oil — both at the same daily dose of 1.1 grams of combined omega-3s, for 12 weeks. Neither the participants nor the researchers knew who was taking which oil until the results were unblinded.

The krill oil group's blood EPA levels rose 1.4 times more than the fish oil group's. DHA rose 1.5 times more. Same dose, same duration, different outcome — the kind of head-to-head design that isolates delivery form as the variable that matters.

That finding lines up with earlier work. A 2011 crossover study out of Leibniz University Hannover compared krill oil against two different fish oil formulations in the same twelve volunteers, measuring how much EPA and DHA actually showed up in blood plasma over 72 hours. Krill oil came out on top against both fish oil forms tested.

Researchers have also looked at why phospholipid content specifically seems to drive this effect, not just krill oil as a category. A 2015 study compared a lower-phospholipid krill oil against a higher-phospholipid krill oil at the same total omega-3 dose — and only the higher-phospholipid version significantly increased how much EPA and DHA showed up in red blood cell membranes, the tissue-level marker researchers consider a better indicator of real absorption than blood plasma alone.

That last point matters beyond the research lab. It means not all krill oil is created equal, either. Phospholipid concentration varies by product — typically somewhere between about 40% and the high 50s. Oceanutra's Antarctic Krill Oil is formulated to guarantee at least 56% phospholipids, at the upper end of that range, for exactly this reason: if phospholipid content is the mechanism behind better absorption, then how much of it is actually in the oil should be part of how you evaluate a bottle.

None of this means fish oil doesn't work — decades of research support its cardiovascular and general health benefits. What the newer research suggests is narrower and more practical: if two products list the same EPA and DHA milligrams on the label, they may not deliver the same result inside your body. Delivery form is a variable worth knowing about, not just total dose.

There's a secondary, more everyday benefit to the phospholipid difference, too. Because krill oil's omega-3s mix more readily with stomach contents rather than floating on top of them, many people report skipping the “fishy burp” reflux that's a common complaint with standard fish oil capsules.

A quick note on safety: krill is a crustacean. As with shrimp, crab, or lobster, anyone with a shellfish or crustacean allergy should avoid krill oil.

Final word: the milligram count on an omega-3 label tells you what went into the capsule. It doesn't tell you what your body does with it once it's there. Delivery form — phospholipid vs. triglyceride — is turning out to be the part of that story most labels leave out.

Written by the Oceanutra Nutrition Team

Curious about how we measure and guarantee phospholipid concentration, or want to see the sourcing behind our Antarctic Krill Oil? Visit the product page →

These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

References
1. 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. Am J Clin Nutr. 2026;124(1):101346. doi:10.1016/j.ajcnut.2026.101346.

2. 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;10:145. doi:10.1186/1476-511X-10-145.

3. Ramprasath VR, Eyal I, Zchut S, Shafat I, Jones PJ. Supplementation of krill oil with high phospholipid content increases sum of EPA and DHA in erythrocytes compared with low phospholipid krill oil. Lipids Health Dis. 2015;14:142. doi:10.1186/s12944-015-0142-y.