Krill Oil

Krill oil explained: omega-3 in phospholipid form from small crustaceans, what absorption and cholesterol reviews found, the knee evidence, and allergy, medicine and pregnancy cautions.

Content last updated October 22, 2026. This page has not been medically reviewed.

Fat-soluble vitaminEuphausia superba oil

What is Krill oil good for?

What the body uses it for, and how strong the evidence is. A normal job in the body is not proof that extra supplements add benefit; each card says which.

Supplies EPA and DHA in phospholipid form

Preliminary or mixed

Krill oil is a source of the marine omega-3 fats EPA and DHA, carried mainly as phospholipids rather than as triglycerides or ethyl esters.

Supplements: In a four-week trial matched for EPA plus DHA, plasma and red-cell levels were not significantly different between krill oil and fish oil. A claim of better absorption is not shown.

Blood fats (LDL cholesterol and triglycerides)

Preliminary or mixed

In pooled trials krill oil lowered LDL cholesterol and triglycerides and raised HDL cholesterol. A change in blood fats is not the same as fewer heart attacks.

Supplements: Meta-analyses found favourable lipid changes. A network meta-analysis found no significant difference from fish oil, and no heart-outcome trials of krill oil were found.

Heart health

Not enough evidence

Krill oil has no heart-attack or stroke outcome trials in the sources read. The large heart trials tested fish oil or purified EPA.

Supplements: Not shown for krill oil. Pooled trials show lipid changes only; blood pressure, glucose and inflammation markers did not change.

Knee osteoarthritis symptoms

Preliminary or mixed

Two meta-analyses of five small trials each disagree: one found no difference from placebo on knee pain or stiffness (small gain in function), the other found benefit on WOMAC scores versus usual care but not on a visual pain scale.

Supplements: Mixed and based on few, small trials; authors of the 2024 review judged krill oil for knee pain not yet justified.

Raising omega-3 levels in the blood

Preliminary or mixed

Taking krill oil raises plasma and red-cell EPA and DHA in healthy adults, at levels comparable to fish oil when the EPA plus DHA amount is matched.

Supplements: Shows the oil is absorbed; says nothing about health benefit by itself.

Connected topics

Open a group to see how each topic connects and how strong the evidence is.

Health goals (3)

Cholesterol BalancePreliminary or mixed
Pooled trials found lower LDL cholesterol and triglycerides and higher HDL with krill oil; results did not differ significantly from fish oil.
Heart HealthPreliminary or mixed
Krill oil lowered LDL cholesterol and triglycerides in pooled trials, but no heart-attack or stroke trials of krill oil were found; the large heart trials used fish oil or purified EPA.
Joint SupportPreliminary or mixed
Two small meta-analyses of knee osteoarthritis disagree on pain; evidence is mixed.

Body systems (4)

Cardiovascular SystemDocumented risk
Trials of marine omega-3 supplements found more atrial fibrillation, mainly above 1 g a day; the review did not separate krill oil.
Heart & CirculationPreliminary or mixed
Krill oil lowered LDL cholesterol and triglycerides in pooled trials, but no heart-attack or stroke trials of krill oil were found; the large heart trials used fish oil or purified EPA.
Bones, Joints & MusclesPreliminary or mixed
Krill oil has been tested for knee osteoarthritis with mixed results.
Musculoskeletal SystemPreliminary or mixed
Krill oil has been tested for knee osteoarthritis with mixed results.

Body parts (2)

HeartPreliminary or mixed
Krill oil lowered LDL cholesterol and triglycerides in pooled trials, but no heart-attack or stroke trials of krill oil were found; the large heart trials used fish oil or purified EPA.
JointsPreliminary or mixed
Two small meta-analyses of knee osteoarthritis disagree on pain; evidence is mixed.

Functional actions (2)

Cardiovascular SupportPreliminary or mixed
Lipid changes in pooled trials; no heart outcome shown.
Joint SupportPreliminary or mixed
Mixed results in knee osteoarthritis trials.

Root causes (1)

Medication Side EffectsDocumented risk
Prescription omega-3 labels warn of increased bleeding, especially with aspirin, clopidogrel or warfarin, and advise monitoring; no krill-specific data were found. Do not change medicines without asking the prescriber.

Biomarkers (3)

TriglyceridesPreliminary or mixed
Pooled krill oil trials found lower triglycerides; krill and fish oil did not differ significantly.
LDL CholesterolPreliminary or mixed
Pooled krill oil trials found lower LDL cholesterol; the 2020 network meta-analysis found no difference from fish oil.
HDL CholesterolPreliminary or mixed
The 2017 meta-analysis found higher HDL with krill oil; the network meta-analysis found no significant difference from fish oil.

Conditions & symptoms (3)

Atrial FibrillationDocumented risk
Marine omega-3 supplements were linked to more atrial fibrillation in trials, mainly above 1 g a day; krill-specific risk is unknown.
HypertriglyceridemiaPreliminary or mixed
Krill oil lowered triglycerides in pooled trials. Regulated medical use for severe high triglycerides is with prescription EPA or omega-3 products, not krill oil supplements.
HypercholesterolemiaPreliminary or mixed
Pooled krill oil trials found lower LDL cholesterol, but they did not test long-term outcomes.

Documented risks and interactions (3)

Heart rhythm risk (atrial fibrillation). Trials of marine omega-3 supplements found more atrial fibrillation, with the signal stronger above 1 g a day. The review did not split results by product, so krill-specific risk is not known.
Bleeding and blood-thinning medicines. Prescription omega-3 labels warn of increased bleeding, especially with aspirin, clopidogrel or warfarin, and ask for monitoring. No krill-specific interaction data were found.
Fish and shellfish allergy caution. Krill are small crustaceans. The prescription label advises telling people with fish or shellfish allergy about possible allergic reactions; no krill-specific allergy study was found.

Explore all 10 omega fatty acids

What krill oil is

NCCIH says krill oil contains omega-3s in the form of phospholipids. [5] Fish oil is mostly sold as triglycerides or ethyl esters. This page is the profile; the side-by-side is in fish oil vs krill oil, and the main fish oil page is fish oil. Krill oil is a dietary supplement, not a prescription medicine; see prescription omega-3 vs supplements.

What the research shows

Evidence labels: promising but limited, mixed, insufficient evidence. Krill oil results should not be applied to fish oil or the reverse, and a change in a blood measure is not a health outcome.

Question	What the source found	Label
Is it absorbed better than fish oil?	A four-week trial in 66 healthy adults gave 1.3 g a day of EPA plus DHA as fish oil ethyl ester, fish oil triglyceride or krill oil. Plasma levels were not significantly different (p = 0.052) and red-cell levels were comparable. [6] A review said human studies were too varied to compare triglyceride and phospholipid forms. [7]	Limited: one short trial; "better absorbed" is a marketing claim not shown by this trial
Cholesterol and triglycerides	2017 meta-analysis of 7 trials (662 people, at least 2 weeks): lower LDL cholesterol (-15.52 mg/dL) and triglycerides (-14.03 mg/dL), higher HDL. [1] 2023 meta-analysis of 14 trials (1,458 people) also found favorable lipid changes but no effect on blood pressure, glucose or inflammation markers. [8]	Promising for blood fats; no heart outcome shown
Krill vs fish oil on lipids	Network meta-analysis of 64 trials: krill oil and fish oil did not differ significantly in triglycerides, LDL, HDL or total cholesterol. [9]	No difference found
Knee pain and osteoarthritis	A 2024 meta-analysis of 5 trials (700 people) found no significant difference from placebo in knee pain or stiffness, with a small gain in physical function, and concluded krill oil is not yet justified for knee pain. [10] A 2025 meta-analysis of 5 trials (730 people) against usual care found benefit on WOMAC pain, stiffness and function but not on a visual pain scale, and called it promising but needing more research. [11]	Mixed
Heart attacks, strokes, dementia, eyes	We looked for krill-oil outcome trials in the sources we could read. Proper evidence not found. The large heart trials tested fish oil or purified EPA. [12]	Insufficient evidence

Amounts and labels

Compare EPA plus DHA per serving rather than the total "krill oil" milligrams. The matched-dose trial was built around EPA plus DHA per day, not around the weight of oil. [6] Krill oil products can also contain other ingredients, so read the whole Supplement Facts panel. See how to read a fish oil label.

Frequently asked questions

Is krill oil better absorbed than fish oil?

In one matched-dose four-week trial, plasma and red-cell EPA plus DHA were not significantly different. [6]

Is krill oil better for cholesterol than fish oil?

A network meta-analysis of 64 trials found no significant difference between them. [9]

Is krill oil safe with a shellfish allergy?

Proper evidence not found for krill oil. Krill are crustaceans, [1] so ask an allergist first.

Does krill oil help knee pain?

Two 2024 and 2025 meta-analyses disagree on pain: one found no significant pain benefit, one found benefit on WOMAC scores. [10][11]

Does krill oil have its own heart-attack research?

Proper evidence not found in the sources we read. [12]

More details: evidence, limits and cautions

The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.

Quick safety points first

Shellfish allergy. Krill are small crustaceans. [1] We searched PubMed for krill oil and shellfish allergy and found nothing usable: Proper evidence not found. Prescription fish-oil-derived omega-3 labels tell people with fish or shellfish allergy to stop the product and seek medical attention if a reaction occurs. [2] If you have a shellfish allergy, ask an allergist before trying krill oil. In a US emergency, call 911.
Blood thinners and surgery. Prescription omega-3 labels say omega-3 acids may prolong bleeding time; people on anticoagulants or antiplatelet drugs should be monitored. [3] Tell your surgical team about all supplements well ahead of an operation. [4] Do not stop a prescribed medicine yourself; ask the prescriber or a pharmacist. We did not find krill-specific interaction data: Proper evidence not found.

Side effects and special groups

Common effects for omega-3 supplements are mild: taste, bad breath, headache, heartburn, nausea, diarrhea. [5]
A meta-analysis of heart trials found marine omega-3 supplements linked to more atrial fibrillation, especially above 1 g a day. [13] The abstract does not split results by product type, so krill-specific risk is Proper evidence not found.
Pregnancy, breastfeeding, children, kidney or liver disease: we found no krill-oil-specific advice. Ask a clinician; see pregnancy and breastfeeding safety and omega-3 safety and interactions.
Quality varies between oils of any type; see quality testing and certifications. Ask a pharmacist about medication interactions.

References

Education, not medical advice. This page is for general information. It does not diagnose or treat any condition and is not a substitute for care from a qualified health professional. Natural does not automatically mean safe. Ask a clinician or pharmacist before changing your care, especially if you take medication, are pregnant or breastfeeding, or have a health condition.