Krill Oil: What It Is, Benefits, and How It Differs From Fish Oil
Krill oil supplements are commonly sold as reddish softgels and can provide the omega-3 fatty acids EPA and DHA.
Key takeaways
- Krill oil is made from small marine crustaceans and provides EPA and DHA.
- A substantial portion of its omega-3s may be associated with phospholipids, unlike many fish oil products.
- Krill oil naturally contains astaxanthin, although the amount varies between products.
- Some studies suggest favorable bioavailability, but not every krill oil product is better absorbed than every fish oil product.
- The total amount of krill oil is not the same as the amount of EPA + DHA.
In this article
- What is krill oil and where does it come from?
- What does krill oil contain?
- How much EPA and DHA does krill oil provide?
- What is the difference between krill oil and fish oil?
- Are omega-3s from krill oil absorbed better?
- What are the main studied benefits of krill oil?
- What effect can krill oil have on triglycerides and cholesterol?
- Can krill oil affect inflammation and joint health?
- What role does astaxanthin play in krill oil?
- How much krill oil can we take, and how much EPA + DHA do we actually get?
- How do we choose a krill oil supplement?
- What side effects, contraindications, and interactions should we know about?
- Frequently asked questions
- Final thoughts
Krill oil is a marine supplement made from krill, very small crustaceans that live in the oceans and play an important role in the marine food chain. Like fish oil, it provides the omega-3 fatty acids EPA and DHA, but there are several important differences between the two products.
A significant portion of the omega-3s in krill oil is associated with phospholipids, and the oil naturally contains astaxanthin, the pigment responsible for its reddish color. These features are often used to market krill oil as a “superior” alternative to fish oil, but the research presents a more nuanced picture.
Some studies suggest good bioavailability of EPA and DHA from krill oil. However, this does not mean that every krill oil product is automatically more effective than fish oil, because the actual EPA and DHA content, formulation, dose, and product quality still matter.
What is krill oil and where does it come from?
Krill oil is extracted from krill, a group of small shrimp-like marine crustaceans. Many supplements are produced from Antarctic krill, particularly Euphausia superba.
Krill feed mainly on phytoplankton and other microscopic organisms. They are also an important food source for whales, seals, penguins, fish, and other marine animals, which makes them an important part of ocean ecosystems.
The oil extracted from krill is used primarily as a source of EPA and DHA. One of the main differences from many fish oil products is the way some of these omega-3 fatty acids are carried in the oil.
In krill oil, a significant proportion of EPA and DHA may be associated with phospholipids. This characteristic is one of the main reasons krill oil is often discussed separately from conventional fish oil.
What does krill oil contain?
Krill oil is not simply EPA and DHA inside a capsule. It contains a mixture of lipids and other naturally occurring components derived from krill.
These may include:
- EPA (eicosapentaenoic acid)
- DHA (docosahexaenoic acid)
- phospholipids
- other fatty acids
- astaxanthin
- other lipid components in varying amounts
Phospholipids are especially notable because they are important components of cell membranes. In many krill oil products, a substantial portion of EPA and DHA is associated with these molecules.
The composition is not identical across all supplements. Krill species, processing methods, and product formulation can all influence the proportions of the different components.
How much EPA and DHA does krill oil provide?
One of the most important things to understand is the difference between the number printed on the front of the package and the amount of omega-3s the product actually provides. A label that says Krill Oil — 1,000 mg does not mean that the supplement contains 1,000 mg of EPA + DHA.
The 1,000 mg refers to the total amount of krill oil. EPA and DHA make up only part of that oil.
For example:
| Hypothetical product | Krill Oil | EPA | DHA | EPA + DHA |
|---|---|---|---|---|
| Product A | 1,000 mg | 120 mg | 70 mg | 190 mg |
| Product B | 1,000 mg | 200 mg | 100 mg | 300 mg |
Both products provide 1,000 mg of krill oil, yet their actual EPA + DHA content differs considerably. This is why the large “1,000 mg Krill Oil” number alone is not enough to compare products.
The Supplement Facts panel should be checked for the amounts of EPA and DHA separately. These numbers usually provide a more useful picture of how much long-chain omega-3 the product actually delivers.
What is the difference between krill oil and fish oil?
Both krill oil and fish oil are marine sources of EPA and DHA. However, their lipid composition, concentration, price, and the amount of research available can differ.
| Feature | Krill Oil | Fish Oil |
|---|---|---|
| Source | Krill | Fatty fish |
| EPA | Yes | Yes |
| DHA | Yes | Yes |
| Phospholipids | Significant proportion in many products | Usually much lower |
| Natural astaxanthin | Yes | Usually no |
| EPA + DHA concentration | Often lower per capsule | Can be considerably higher |
| Capsule size | Often relatively small | Varies |
| Price | Usually higher | Usually more affordable |
| Amount of research | Relatively limited | Much more extensive |
Fish oil itself can appear in several molecular forms, including triglycerides, re-esterified triglycerides, and ethyl esters. This means that “fish oil” is not one standardized product either.
Krill oil has the distinctive features of phospholipids and astaxanthin. Fish oil, however, may provide larger amounts of EPA + DHA per serving and has been studied much more extensively in clinical research.
The comparison should therefore not be reduced to “krill oil is better” or “fish oil is better.” The specific products, doses, EPA and DHA content, and intended use need to be compared.
Are omega-3s from krill oil absorbed better?
This is probably the best-known claim about krill oil. Because some EPA and DHA in krill oil is associated with phospholipids, researchers have investigated whether these omega-3s may have greater bioavailability than omega-3s in some fish oil formulations.
Some human studies support this possibility. In one crossover study involving 15 healthy participants, a single dose of krill oil resulted in greater exposure to EPA + DHA in plasma phospholipids over 72 hours than fish oil at comparable doses.
The researchers also observed substantial individual variability and emphasized the need for longer-term studies. Their findings did not support the simple explanation that phospholipids are always absorbed better than triglycerides.
A later meta-analysis also found signs that certain krill oil formulations and lower doses may have favorable bioavailability. However, the results were heterogeneous, and both the product form and dose influenced the comparisons.
The practical conclusion is that krill oil can be a highly bioavailable source of EPA and DHA, but there is no universal rule that every krill oil product is better absorbed than every fish oil product.
What are the main studied benefits of krill oil?
Most proposed benefits of krill oil are linked to its EPA and DHA content, phospholipids, and astaxanthin. Clinical research has investigated several potential effects, although the evidence is not equally strong for all of them.
Research has focused particularly on:
- triglycerides
- cholesterol and other blood lipids
- EPA and DHA levels in the body
- inflammatory markers
- cardiovascular health
- joint pain
Some of these areas have produced interesting findings. However, the number of clinical studies specifically evaluating krill oil remains relatively small.
This distinction is important because findings from omega-3 research in general cannot automatically be presented as proven benefits of krill oil. A result demonstrated with another omega-3 formulation may not apply to a particular krill oil supplement.
What effect can krill oil have on triglycerides and cholesterol?
Blood lipids are one of the better-studied areas for krill oil. Research has looked at possible changes in triglycerides, LDL cholesterol, HDL cholesterol, and other lipid markers.
A meta-analysis of seven randomized trials involving 662 participants found reductions in triglycerides and LDL and an increase in HDL after krill oil supplementation. The authors also emphasized that larger clinical trials are needed to better evaluate cardiometabolic effects and cardiovascular outcomes.
These findings do not mean that krill oil should be used as a treatment for high cholesterol or hypertriglyceridemia. Studies involving prescription omega-3 products with precise high doses represent a different category of evidence.
Results from prescription omega-3 products should not automatically be transferred to an ordinary krill oil supplement. For consumers, the actual amount of EPA + DHA provided by the product remains one of the most important details to check.
Can krill oil affect inflammation and joint health?
Krill oil is frequently marketed for joint health because it provides EPA and DHA, phospholipids, and astaxanthin. Some smaller studies have suggested possible effects on inflammatory markers or joint symptoms.
A major randomized clinical trial published in JAMA in 2024 provided more cautious results. It included 262 adults with knee osteoarthritis, significant pain, and MRI-confirmed effusion-synovitis.
Participants received 2 g of krill oil per day or placebo for 24 weeks. Krill oil did not reduce knee pain more than placebo in the population studied.
This study does not prove that krill oil can never affect any aspect of joint health. It does show why preliminary findings and biological mechanisms should not be turned too quickly into claims such as “krill oil reduces joint pain.”
At present, the evidence does not support presenting krill oil as a treatment for knee osteoarthritis. More research would be needed to establish benefits for other joint-related outcomes or populations.
What role does astaxanthin play in krill oil?
The characteristic reddish color of krill oil comes largely from astaxanthin. Astaxanthin is a carotenoid found in marine organisms and has antioxidant properties.
It is also present in salmon, trout, shrimp, and other organisms that obtain the pigment through the food chain. Its natural presence is one of the features that distinguishes krill oil from most conventional fish oil products.
However, “contains astaxanthin” is not the same as “provides a dose of astaxanthin with clinically demonstrated benefits.” The amount found in krill oil can vary substantially between products.
It may also be much lower than the doses used in studies investigating astaxanthin as a separate supplement. For this reason, astaxanthin is better viewed as a distinctive natural component of krill oil, rather than a guarantee of a specific antioxidant effect in the body.
How much krill oil can we take, and how much EPA + DHA do we actually get?
There is no single universal krill oil dose that is appropriate for everyone. Clinical studies have used different products, concentrations, and amounts.
Two capsules containing the same total amount of krill oil can also provide very different quantities of EPA and DHA. This is why it is more useful to look for:
EPA: ___ mg
DHA: ___ mg
rather than focusing only on:
Krill Oil: ___ mg
The Serving Size should also be checked carefully. If the label lists 200 mg of EPA + DHA for a Serving Size of two capsules, the two capsules together provide that amount.
Doses used for specific medical conditions should not be copied directly from a study and applied to an over-the-counter supplement. The product, concentration, population, and clinical context may all be different.
How do we choose a krill oil supplement?
The largest number printed on the front of the package is not necessarily the most useful information. The complete label gives a better picture of what the supplement actually contains.
| What to check | Why it matters |
|---|---|
| Serving Size | Shows how many capsules make up one serving |
| Krill Oil | Shows the total amount of oil |
| EPA | Shows how much EPA the product actually provides |
| DHA | Shows how much DHA the product actually provides |
| EPA + DHA | Makes product comparisons more useful |
| Phospholipids | Some products list the amount or percentage |
| Astaxanthin | The amount can vary considerably |
| Other Ingredients | Shows what else is included in the capsule |
| Allergen information | Important because krill is a crustacean |
| Storage instructions | Polyunsaturated oils can be susceptible to oxidation |
A product labeled “1,000 mg krill oil” should not automatically be considered more concentrated than a 500 mg product. Depending on formulation, the 1,000 mg product may actually provide less EPA + DHA.
Independent testing can provide additional information about product identity, purity, and content. However, a verification seal does not mean that the supplement has been proven effective for treating a disease.
What side effects, contraindications, and interactions should we know about?
Krill oil is generally well tolerated in clinical studies, but some people may experience digestive or other adverse effects. These effects are often mild, although individual responses can vary.
Possible side effects include:
- nausea
- abdominal discomfort
- heartburn
- loose stools or diarrhea
- unpleasant taste or odor
- burping
Krill is a crustacean, which is an important consideration for people with shellfish allergies. Anyone with this type of allergy should not simply treat krill oil as an ordinary alternative to fish oil without medical advice.
Higher doses of omega-3 also require caution for people taking anticoagulants or other medications that affect blood clotting. Supplement use in these situations should be discussed with a doctor or pharmacist.
People who are pregnant or breastfeeding, have medical conditions, or take multiple medications should also discuss supplement use with a healthcare professional. Individual medical circumstances may change whether a particular krill oil product or dose is appropriate.
Frequently asked questions
Is krill oil the same as fish oil?
No, although both provide EPA and DHA. They come from different marine organisms and have different lipid compositions, while krill oil also naturally contains astaxanthin and often has a substantial proportion of omega-3 associated with phospholipids.
Is krill oil absorbed better than fish oil?
Some studies have found favorable bioavailability for krill oil, and a recent meta-analysis suggests potential advantages for certain doses and formulations. However, the evidence does not support saying that every krill oil product is always better absorbed than every fish oil product.
Does 1,000 mg of krill oil mean 1,000 mg of omega-3?
No, because 1,000 mg refers to the total amount of krill oil. The actual amounts of EPA and DHA should be checked separately in the Supplement Facts panel.
Does krill oil contain astaxanthin?
Yes, krill oil naturally contains astaxanthin. The amount varies between products, and its presence alone does not guarantee the benefits reported in studies using specific doses of astaxanthin.
Is krill oil good for joints?
The evidence is mixed and does not currently support using krill oil as a treatment for knee osteoarthritis. A major randomized JAMA trial published in 2024 found that 2 g per day for 24 weeks did not reduce knee pain more than placebo in people with knee osteoarthritis and effusion-synovitis.
Can people with shellfish allergies take krill oil?
Krill is a crustacean, so shellfish allergy is an important safety consideration. People with this type of allergy should discuss krill oil with a doctor or allergist before using it.
Final thoughts
Krill oil is a marine source of EPA and DHA with a composition that differs from many fish oil products. Phospholipids and astaxanthin are the two characteristics that most clearly distinguish it.
Some research suggests that EPA and DHA from certain krill oil formulations may have favorable bioavailability. However, this should not be turned into the general claim that krill oil is always better absorbed or more effective than fish oil.
Evidence concerning effects on blood lipids is promising, but the research base remains relatively small. For joint health, a large recent clinical trial did not find a benefit for knee osteoarthritis pain in the population studied.
When choosing a product, the actual amount of EPA + DHA is more informative than the number of milligrams of krill oil displayed on the front of the package. Serving Size, EPA, DHA, phospholipids, astaxanthin, allergens, and product quality should be considered together.
References
- Köhler A, et al. Bioavailability of fatty acids from krill oil, krill meal and fish oil in healthy subjects — a randomized, single-dose, cross-over trial. Lipids in Health and Disease. 2015. pmc.ncbi.nlm.nih.gov
- Schuchardt JP, et al. 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 in Health and Disease. 2011. pmc.ncbi.nlm.nih.gov
- Comparison of omega-3 polyunsaturated fatty acids bioavailability in fish oil and krill oil: network meta-analyses. Food Chemistry: X. 2024. pmc.ncbi.nlm.nih.gov
- Laslett LL, et al. Krill Oil for Knee Osteoarthritis: A Randomized Clinical Trial. JAMA. 2024. jamanetwork.com
- Ursoniu S, et al. Lipid-modifying effects of krill oil in humans: systematic review and meta-analysis of randomized controlled trials. Nutrition Reviews. 2017. pubmed.ncbi.nlm.nih.gov
- Salem N Jr, et al. Comparison of bioavailability of krill oil versus fish oil and health effect. Vascular Health and Risk Management. 2015. pmc.ncbi.nlm.nih.gov
- NIH Office of Dietary Supplements. Omega-3 Fatty Acids — Fact Sheet for Health Professionals. ods.od.nih.gov
- National Center for Complementary and Integrative Health. Omega-3 Supplements: What You Need to Know. nccih.nih.gov
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