26/04/2026
An overview of research to settle the krill vs fish oil debate. At low doses, krill oil offers more bio-availability, but if taking more than 2g of fish oil, the fish oil becomes better. For me, I always prescribe above 2g, as am looking for the anti-inflammatory and cholesterol lowering effects which this can support, so will always achieve better results with fish oil. And whilst I am a fan of astaxanthin for anti-ageing, I offer a collagen powder with this in it. For top quality high dose (750mg EPA, 250mg DHA) fish oil capsules, please see me in clinic.
Krill oil contains EPA and DHA bound primarily to phospholipids. Standard fish oil delivers EPA and DHA as triglycerides or, in concentrated products, as ethyl esters. The phospholipid-form difference is the basis of bioavailability claims that range from "two to three times more" to "eight times more" depending on the source. Per gram of EPA+DHA, krill oil typically retails for five to ten times more than standard fish oil.
The bioavailability claim has a specific origin. Bunea and colleagues published a study in 2004 (Alternative Medicine Review) comparing krill oil to menhaden fish oil in 120 patients with elevated cholesterol. The study measured lipid changes (total cholesterol, LDL, HDL, triglycerides), not EPA+DHA bioavailability directly. Krill produced larger reductions in lipid markers, and bioavailability claims drew on those results indirectly. The doses weren't matched. The krill arms received 1 to 3 grams per day. The fish oil arm received 3 grams. Lipid endpoints aren't a direct readout of how much EPA and DHA reached the bloodstream. Maki and colleagues (2009) ran a follow-up trial that compared 2 grams of krill oil to 2 grams of menhaden oil, but the products contained different EPA+DHA concentrations per gram, so the dose of the active compounds still wasn't matched.
When the dose was matched and plasma EPA+DHA was measured directly, the difference between forms was small.
Yurko-Mauro and colleagues (2015, Lipids in Health and Disease) ran a three-arm randomized trial in 66 healthy adults. Each arm received 1.3 grams per day of EPA+DHA for four weeks: krill oil, fish oil triglyceride form, or fish oil ethyl ester form. After four weeks, plasma EPA+DHA was 118 µg/mL on krill, 108 on fish oil triglyceride, and 91 on fish oil ethyl ester. The differences between the three groups were small enough that they could plausibly be chance. Bioavailability differed by less than 24% across all three forms. Red blood cell omega-3 indexes were comparable across all three. Four of the six authors of this trial are employees of DSM Nutritional Products, which is a major fish oil supplier.
Earlier work from Ulven and colleagues (2011, Lipids) reached a similar conclusion. They randomized 113 subjects to krill oil at 543 mg EPA+DHA per day, fish oil at 864 mg EPA+DHA per day, or no supplement. The krill arm received 63% of the EPA+DHA dose of the fish oil arm. Plasma EPA, DHA, and DPA increased equivalently in both groups. Krill produced parity with fish oil at a meaningfully lower dose, suggesting a real phospholipid-form advantage at lower dose ranges.
A 2024 network meta-analysis pooled 26 studies and found krill oil shows superior bioavailability overall, with one important caveat. At doses under 2,000 mg, krill outperforms fish oil on omega-3 absorption. Above that threshold, fish oil and krill oil reach comparable omega-3 indexes. Whether the low-dose pharmacokinetic edge translates into a difference in long-term cardiovascular or cognitive outcomes has not been demonstrated.
Krill oil also costs more to produce than fish oil. Antarctic krill comes from a remote, quota-limited fishery. The endogenous lipases in krill degrade the phospholipids quickly, so processing has to happen at sea or under tight cold chain. The gentler extraction methods needed to preserve phospholipid structure have lower throughput than standard fish oil refining. A production-cost premium of roughly two to three times standard fish oil is reasonable. The retail premium of five to ten times reflects positioning beyond production cost.
Two caveats. First, the Yurko-Mauro between-group difference was right at the edge of statistical significance, trends-level rather than firmly null. The matched-dose data does not formally prove equivalence. It shows a difference too small to reach significance with that sample size. Second, krill oil contains astaxanthin and choline, which fish oil generally does not. Whether those additional compounds confer independent benefit at the doses present in commercial krill products has not been established.
For someone targeting a specific omega-3 index at typical clinical doses (1.5 to 3 grams of EPA+DHA per day), the matched-dose evidence indicates that any well-formulated EPA+DHA source will get them there. For someone using lower doses (under 2 grams per day) and prioritizing pharmacokinetic uptake, krill has a defensible edge.
Yurko-Mauro et al., Lipids in Health and Disease, 2015
Ulven et al., Lipids, 2011
Pham et al., Food Chemistry: X, 2024
Bunea et al., Alternative Medicine Review, 2004