Krill oil is a supplement rich in the omega-3 fatty acids EPA and DHA, sourced from tiny shrimp-like crustaceans. What sets it apart structurally is that these omega-3s are bound to phospholipids, which the body may absorb somewhat more efficiently than the triglyceride form found in standard fish oil.
Krill oil is studied in relation to metabolic health, inflammation, cardiovascular and cognitive function, and joint comfort. It also naturally contains astaxanthin, an antioxidant that gives it a distinctive red colour and is of separate research interest in its own right.
An important note before we go further: krill is a crustacean. Krill oil is not suitable for anyone with a shellfish or crustacean allergy, and this is worth knowing before considering it, regardless of any of the benefits discussed below.
What Exactly Is Krill Oil?
Krill are small, red crustaceans resembling miniature lobsters, found in oceans worldwide. Quality krill oil supplements are typically sourced from Antarctic krill (Euphausia superba), and like fish oil, provide the omega-3s DHA and EPA.
The key structural difference is that krill oil delivers omega-3s in phospholipid form, which is thought to integrate somewhat more readily into cells compared with the triglyceride or ethyl ester forms in fish oil. It also naturally contains choline and astaxanthin.
According to USP (United States Pharmacopeia) standards, krill oil should contain 30-59% phospholipids, at least 10% EPA, 5% DHA (primarily in phospholipid form), and 0.005% astaxanthin. Superba® krill oil is one of the more researched branded options in this space.
Omega-3 & Fatty Acids
What Research Says About Krill Oil
Metabolic Health
Krill oil is studied in relation to several aspects of metabolism, including energy production, blood sugar regulation, and cholesterol, largely attributed to its combination of omega-3s, phospholipids, and astaxanthin.
Mitochondrial Function and Energy Production
The omega-3s in krill oil are relevant to mitochondrial function — the cellular structures responsible for energy production — and are studied for a role in fat metabolism and ATP production, the primary energy molecule cells use.
Liver Health
The liver plays a central role in metabolism, and krill oil is studied for a possible role in reducing fat accumulation in the liver — an area of genuine research interest given its potential relevance to insulin resistance, though this remains an area of ongoing study rather than an established treatment for any diagnosed liver or metabolic condition.
Lipid Metabolism and Triglycerides
Several studies have explored krill oil’s effect on blood lipids, with some research reporting triglyceride reductions in the range of 12% or more, alongside support for healthy HDL (“good”) cholesterol — effect sizes vary between studies and populations, so it’s worth treating any single specific percentage as indicative rather than guaranteed.
Inflammation and Oxidative Stress
Krill oil’s omega-3 and astaxanthin content has been studied for anti-inflammatory effects. One well-known trial found meaningful reductions in C-reactive protein (CRP), a key inflammation marker — around 20% after 7 days and higher after 30 days of use. It’s worth being clear about this study’s context: participants had diagnosed cardiovascular disease, rheumatoid arthritis, or osteoarthritis with elevated CRP to begin with, so this specific magnitude of effect is most directly relevant to people managing those diagnosed conditions (under medical care) rather than a guaranteed effect for the general population.
Muscle Health and Function
Krill oil is studied in relation to age-related muscle loss. One study in adults over 65 found improvements in knee strength, grip strength, and muscle thickness — a genuinely interesting single-study finding worth knowing about, though not yet a broad, settled conclusion.
Joint Comfort
For people with mild to moderate joint discomfort, some clinical trials (including the CRP-related trial above, in people with diagnosed joint conditions) have found reductions in joint discomfort and support for cartilage-related comfort — again, this evidence is strongest for people with a diagnosed condition rather than general joint maintenance in healthy people.
Mood and Cognitive Function
EPA and DHA are structural components of brain cell membranes and are studied in relation to memory, focus, and mood. Astaxanthin is of additional research interest for its antioxidant properties in relation to brain cell protection.
PMS and Menstrual Discomfort
Some clinical research has explored krill oil in relation to premenstrual symptoms, including mood fluctuations, irritability, and cramping, with encouraging findings in the trials conducted so far — though this remains a smaller body of research than some of the other areas covered here.
Skin Health
Some human studies have explored krill oil’s effect on skin barrier function, hydration, and elasticity, with generally positive findings, though — as with several areas above — this research base is smaller than the inflammation and lipid research.
Dry Eyes
Some research has explored krill oil for dry eye symptoms, with a few studies suggesting it may compare favourably with fish oil for improving tear quality and reducing irritation — this is an interesting area, though based on a relatively small number of studies so far, rather than settled, large-scale evidence.
Immune Function
The omega-3s in krill oil are studied for a role in immune cell activity, including natural killer (NK) cells — this is a reasonable area of research interest, though “supports immune function” is a more accurate description than a guarantee of fewer infections or illness.
Krill Oil vs Fish Oil: Understanding the Difference
Both krill oil and fish oil are good sources of omega-3 EPA and DHA, with one key structural difference affecting how the body uses them.
Omega-3s in krill oil are bound to phospholipids, thought to integrate somewhat more readily into cells; fish oil omega-3s exist mainly in triglyceride form. This absorption difference is one reason some people choose krill oil, even though fish oil supplements often contain a notably higher concentration of omega-3 per capsule — which matters in practice, since better absorption of a smaller amount doesn’t automatically outperform a much larger amount of a slightly less efficiently absorbed form. Both are reasonable choices, and the right one depends on your priorities (dose per capsule, cost, or the phospholipid/astaxanthin angle).
Quick Comparison: Krill Oil vs Fish Oil
| Feature | Krill Oil | Fish Oil |
|---|---|---|
| Omega-3 Form | Phospholipid | Triglyceride |
| Absorption | Some research suggests more efficient | Good |
| Antioxidant | Contains astaxanthin | None |
| Omega Concentration per Capsule | Typically lower | Typically higher |
| Research Volume | Growing, but smaller (~40 studies) | Extensive (1,200+ studies) |
A Note on the Omega-3 Index
The Omega-3 Index — the percentage of EPA and DHA in red blood cells — is one way researchers measure omega-3 status, with a level above 8% generally considered a reasonable target.
Because krill oil’s phospholipid form may be somewhat better absorbed, some research suggests a slightly lower daily dose may achieve a similar Omega-3 Index compared with fish oil — one study found roughly 820mg of EPA+DHA from krill oil achieved a similar result to about 1,220mg from fish oil. That said, since krill oil capsules generally contain less total omega-3 than fish oil capsules, this efficiency doesn’t fully offset the lower concentration — worth bearing in mind when comparing overall value and total capsules needed per day.
Safety and Side Effects
Shellfish/crustacean allergy: as noted above, krill oil is not suitable for anyone with a shellfish or crustacean allergy — this is the most important safety consideration for this specific supplement, given what krill actually is.
Beyond this, krill oil is generally well tolerated, with mild digestive effects (such as burping with a fishy aftertaste, or mild stomach upset) being the main things some people notice — generally less pronounced than with standard fish oil, given krill oil’s different fat structure.
Blood-thinning medication: some doctors advise caution with omega-3 supplements (krill or fish oil) alongside blood-thinning medication such as warfarin, given a theoretical bleeding risk. A 2016 study found no significant increase in bleeding risk when krill or fish oil was taken alongside warfarin under proper monitoring — reassuring, but this is still worth discussing with your doctor if you’re on blood thinners or platelet inhibitors, so any monitoring needed can be arranged appropriately, rather than assuming it’s automatically fine.
Recommended Dosage
Typical krill oil doses range from 1,000mg to 4,000mg daily, depending on the product’s concentration and your goal. Since many krill oil products provide around 20-24% EPA+DHA by weight, reaching a combined EPA+DHA intake of 800mg or more (a commonly referenced target relating to Omega-3 Index research) may mean a total krill oil dose in the region of 3,500-4,000mg daily — worth checking against the specific concentration on your product’s label rather than assuming.
Some manufacturers combine krill oil with extra astaxanthin, or blend it with fish oil to boost overall EPA+DHA content per serving.
Final Thoughts
Krill oil is a reasonably well-studied source of omega-3s, with a genuinely interesting structural difference (phospholipid-bound omega-3s, plus astaxanthin) compared to standard fish oil — though its research base, while growing, remains considerably smaller than fish oil’s. Some of its more specific benefits (joint comfort, inflammation markers) have their strongest evidence in people with diagnosed conditions rather than the general population, which is worth keeping in mind when reading about specific percentage improvements.
If you don’t regularly eat oily fish like salmon, sardines, mackerel, or herring, krill oil is one reasonable way to help close that gap — provided you don’t have a shellfish allergy. Checking and monitoring your Omega-3 Index over time is a more reliable way to judge whether it’s working for you than relying on how you feel day to day.
Disclaimer: This article is for informational purposes only and does not constitute medical advice. Krill oil is not suitable for anyone with a shellfish or crustacean allergy. Always consult your GP before starting any supplement, particularly if you take blood-thinning medication or have an existing health condition.
