Krill oil v fish oil — which omega-3 supplement should you choose? If you’ve been researching this question, you’ve come to the right place. Both krill oil and fish oil contain omega-3 fatty acids, and both claim impressive health benefits. So which one should you actually buy?
This guide breaks down the real differences — not just the marketing — so you can make an informed decision.
What Are They and Where Do They Come From?
Fish oil is extracted from the tissue of fatty fish such as salmon, mackerel, sardines, and anchovies. It has been used as a supplement for decades and is the most widely researched source of omega-3.
Krill oil is extracted from tiny shrimp-like crustaceans called Antarctic krill (Euphausia superba). Despite being small, krill are one of the most abundant creatures on the planet and form a critical part of the ocean food chain. Krill oil is a newer supplement but has attracted significant research interest over the past 15 years.
Both contain the two omega-3 fatty acids that matter most for human health: EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid).
The Key Difference: How Your Body Absorbs Them
This is where things get interesting — and where krill oil has a genuine advantage.
In fish oil, EPA and DHA are carried in the form of triglycerides. Your body can absorb these reasonably well, but it requires several digestive steps first.
In krill oil, EPA and DHA are carried in the form of phospholipids — the same structure that makes up your cell membranes. Because of this, your body recognises and absorbs them more readily, with less digestive processing required.
Some studies suggest krill oil achieves similar increases in blood omega-3 levels at lower doses than fish oil, though the research is not yet conclusive and results vary between trials. What is consistently supported is that the phospholipid form requires less digestive processing — which may partly explain why krill oil is generally better tolerated than fish oil.
Krill Oil Contains Something Fish Oil Doesn’t
Krill oil contains a naturally occurring antioxidant called astaxanthin, which gives it its distinctive red colour. Astaxanthin is one of the most powerful antioxidants found in nature. It helps protect the omega-3 fatty acids in krill oil from oxidising (going rancid) — both on the shelf and after you’ve swallowed them.
Fish oil does not naturally contain astaxanthin. Some manufacturers add synthetic antioxidants instead, but these are not the same thing.
This matters practically: fish oil capsules are more prone to oxidation, which is why fish oil often produces that unpleasant “fishy burp.” Rancid omega-3 oils are not only unpleasant — there is some evidence they may actually be counterproductive to health.
Krill oil tends to be much better tolerated, with far fewer reports of digestive discomfort or aftertaste.
What Are the Health Benefits?
Heart health — EPA and DHA support healthy triglyceride levels, blood pressure regulation, and overall cardiovascular function. This is the most well-established benefit of omega-3 supplementation.
Joint health and inflammation — Omega-3s have anti-inflammatory properties that can help with joint stiffness and discomfort, particularly relevant for people with arthritis or those who are physically active.
Brain and cognitive function — DHA is a structural component of brain tissue. Adequate DHA intake is associated with memory, focus, and mood regulation.
Eye health — DHA is also found in high concentrations in the retina. Regular omega-3 intake supports long-term eye health.
What About Sustainability?
This is a fair question. Antarctic krill are among the most abundant creatures on earth — scientific estimates put their total biomass in the Southern Ocean at between 300 and 400 million tonnes — and the fishery is among the most tightly regulated in the world, certified by the Marine Stewardship Council (MSC). The annual catch represents less than 1% of the estimated population.
Fish oil sustainability varies considerably depending on the source. Some fish oil products are responsibly sourced; others are not. When buying fish oil, it’s worth checking for MSC certification or similar.
High-quality krill oil sourced from certified Antarctic fisheries is generally considered the more consistently sustainable choice.
The Price Difference
Fish oil is generally cheaper. You can find basic fish oil capsules for a few pounds per month in most UK pharmacies.
Krill oil costs more — typically two to four times the price of a comparable fish oil product. Some research suggests you may need a lower dose to achieve a comparable effect, which can partially close the cost gap, though individual responses vary.
If budget is your primary concern, a good quality fish oil is still far better than no omega-3 supplementation at all. But if you want the most effective option with better tolerability and the added antioxidant benefit of astaxanthin, krill oil is worth the extra investment.
So Which Should You Choose?
Choose fish oil if: you want the most affordable option and are comfortable taking a higher dose.
Choose krill oil if: you want better absorption, dislike the fishy aftertaste many fish oils cause, or want the added benefit of astaxanthin.
For most people looking for a high-quality, effective omega-3 supplement, krill oil is the better choice — provided you buy from a reputable source.
What to Look for When Buying Krill Oil in the UK
Not all krill oil supplements are created equal. Here’s what to check before buying:
Source: Look for Antarctic krill, ideally from a certified sustainable fishery
EPA and DHA content: Check the actual amounts per capsule, not just the total krill oil content
Manufacturing standards: GMP (Good Manufacturing Practice) certification means the product has been produced under verified quality conditions
No unnecessary fillers: The fewer the additives, the better
Our Pure Antarctic Krill Oil
Our Pure Antarctic Krill Oil is sourced from certified Antarctic waters and manufactured right here in the UK under GMP (Good Manufacturing Practice) and ISO 9001 quality standards — giving you confidence in both the purity and potency of what you’re taking.
Each 500mg capsule delivers a clean, well-absorbed dose of omega-3 EPA and DHA in natural phospholipid form, with astaxanthin content intact. No unnecessary fillers. No fishy aftertaste.
As a small UK family business, we don’t compromise on quality. Every product comes with a 30-day money-back guarantee — so there’s no risk in trying it.
Shop Pure Antarctic Krill Oil — currently on offer at £15.99 →
The Bottom Line
Both fish oil and krill oil deliver valuable omega-3 fatty acids, but krill oil offers meaningful advantages in absorption, tolerability, and additional antioxidant protection. For most people, it represents the smarter long-term investment in their health.
The most important thing is simply to be taking a quality omega-3 supplement consistently — because most UK adults are not getting enough from diet alone.
For more on omega-3 research, the NHS has guidance on fish oils here.
Disclaimer: This article is for informational purposes only and does not constitute medical advice. Food supplements are not medicines and are not intended to diagnose, treat, cure or prevent any disease. If you have a specific health condition or are taking medication, please consult your GP before starting any new supplement.