What Is Krill Oil? Omega-3s, Phospholipids, Astaxanthin, Benefits and Safety

Krill oil is a marine oil derived from small crustaceans known as krill. Like fish oil, it provides the long-chain omega-3 fatty acids EPA and DHA, but its lipid composition is different: a substantial portion of the omega-3s in krill oil is associated with phospholipids rather than existing only in triglyceride or ethyl-ester forms.

Krill oil also naturally contains phospholipids and the red-orange carotenoid astaxanthin. These features have made it an active area of research in omega-3 nutrition.

However, terms such as “phospholipid-bound,” “better absorbed,” and “more bioavailable” need context. Human studies have used different krill oils, fish oils, EPA and DHA doses, phospholipid concentrations, study durations, and pharmacokinetic measurements. Results from one formulation should not automatically be applied to every krill oil supplement.

“Krill oil is a source of EPA and DHA with a distinctive phospholipid-rich lipid profile, but its clinical effects depend on the actual omega-3 dose, formulation, population, and outcome studied.”

What Are EPA and DHA?

EPA, or eicosapentaenoic acid, and DHA, or docosahexaenoic acid, are long-chain omega-3 fatty acids found primarily in marine foods and marine oils.

They are incorporated into cell membranes and participate in normal physiological processes involving lipid signaling and membrane structure.

EPA and DHA have been widely studied in areas including:

• Blood triglyceride levels
• Cardiovascular health
• Cell-membrane composition
• Brain and retinal structure
• Inflammatory signaling pathways

But the amount matters.

A supplement containing krill oil should not be evaluated only by the total weight of the oil. The amount of actual EPA and DHA—or total omega-3s containing EPA and DHA—is more informative when comparing omega-3 intake.

What Are Phospholipids in Krill Oil?

Phospholipids are a major class of lipids found throughout the human body, including in cell membranes.

A phospholipid has both water-interacting and fat-interacting regions. This amphiphilic structure helps phospholipids organize into biological membranes and interact differently with digestive environments than completely nonpolar fats.

In krill oil, a portion of EPA and DHA can be associated with phospholipids.

This differs from many conventional fish oils, where EPA and DHA may primarily occur in triglyceride, re-esterified triglyceride, or ethyl-ester forms.

That chemical difference is real—but it does not mean phospholipid-bound omega-3s bypass digestion or move directly into human cells.

Are Krill Oil Omega-3s Better Absorbed?

Human research suggests that the form in which EPA and DHA are delivered can influence their absorption and incorporation into blood lipids.

Some clinical studies have reported greater increases in certain EPA or DHA measurements with krill oil compared with specific fish-oil formulations.

For example, studies have compared:

• Acute blood concentrations after a single dose
• Plasma phospholipid EPA and DHA
• Red-blood-cell fatty acids
• The Omega-3 Index
• Area under the concentration-time curve

A recent randomized trial in healthy adults also reported greater increases in plasma EPA and DHA after 12 weeks of krill oil compared with fish oil when both groups received similar amounts of omega-3 fatty acids.

However, this does not establish one universal absorption advantage.

Fish oil itself can be formulated in several ways, including triglycerides, re-esterified triglycerides, ethyl esters, emulsions, and phospholipid-enhanced systems. Food intake and dose can also substantially affect absorption.

For a closer comparison of phospholipid-rich krill oil with different fish-oil formulations, including what human studies actually show about absorption and bioavailability, read our guide to krill oil vs fish oil, phospholipids, and omega-3 bioavailability.

What Is Astaxanthin?

Astaxanthin is a naturally occurring carotenoid pigment responsible for much of the reddish color seen in krill, salmon, and several other marine organisms.

It has antioxidant activity in chemical and experimental systems.

In krill oil, naturally occurring astaxanthin also contributes to the oil’s characteristic red color.

However, its presence should not automatically be translated into claims that the finished supplement:

• Protects every cell from oxidative damage
• Prevents aging
• Prevents cardiovascular disease
• Protects the brain from neurodegeneration
• Prevents the oil from becoming rancid indefinitely

The clinical significance of astaxanthin depends on the actual amount, preparation, duration, and outcome studied.

What Are the Potential Benefits of Krill Oil?

Most proposed benefits of krill oil relate to its EPA and DHA content, although the phospholipid matrix and astaxanthin have also attracted research interest.

Human studies have primarily examined outcomes involving:

• Omega-3 status
• Blood lipids
• Joint symptoms and function
• Selected inflammatory biomarkers
• Other cardiometabolic measures

The strength of evidence differs substantially across these areas.

What Does Research Show About Krill Oil and Blood Lipids?

Krill oil has been evaluated in randomized trials for effects on triglycerides, LDL cholesterol, HDL cholesterol, and other lipid measures.

A systematic review and meta-analysis of randomized controlled trials reported changes in several blood-lipid measures, including reductions in triglycerides and LDL cholesterol and increases in HDL cholesterol.

However, the studies differed in:

• Krill-oil dose
• EPA and DHA content
• Participant health status
• Study duration
• Control treatment
• Baseline lipid levels

These results therefore should not be converted into a promise that a particular low-dose krill oil supplement will reduce triglycerides by a specific percentage.

Dietary supplements also should not be presented as substitutes for lipid-lowering medication or medical management when treatment is clinically indicated.

Does Krill Oil Help With Joint Pain?

The evidence is mixed.

Individual randomized trials have reported improvements in selected pain, stiffness, or function outcomes with particular krill-oil preparations.

However, recent larger trials and systematic reviews have not produced completely consistent results.

For example, a 2024 systematic review of five randomized trials involving approximately 700 participants found no significant overall improvement in knee pain or stiffness compared with placebo, although a small improvement in physical function was reported.

A separate large randomized clinical trial in people with knee osteoarthritis and MRI-detected effusion-synovitis found that 2 grams of krill oil daily did not improve knee pain over 24 weeks compared with placebo.

Other meta-analyses using different study-selection and statistical methods have reported more favorable WOMAC outcomes.

Persistent joint pain, swelling, restricted movement, or worsening symptoms deserve appropriate evaluation rather than relying only on an omega-3 supplement.

Does Krill Oil Support Brain Health?

DHA is an important structural fatty acid in neural tissue, and both EPA and DHA have been extensively studied in nutrition research.

However, the presence of DHA in a krill-oil supplement does not prove that the finished product improves memory, concentration, cognitive performance, or prevents age-related cognitive decline.

Clinical cognitive outcomes depend on many factors, including:

• EPA and DHA dose
• Baseline omega-3 status
• Age
• Diet
• Study duration
• Cognitive status
• The outcome actually measured

Statements such as “DHA crosses the blood-brain barrier” should therefore not be used as a shortcut to claim improved memory or mental focus.

Does Krill Oil Support Heart Health?

EPA and DHA are extensively studied omega-3 fatty acids, and higher-dose omega-3 interventions can meaningfully affect triglyceride levels.

But cardiovascular outcomes are more complex than a single biomarker.

A krill-oil supplement should not be described as:

• Preventing heart disease
• Correcting an abnormal heart rhythm
• Replacing prescription omega-3 therapy
• Replacing cholesterol or blood-pressure medication
• Guaranteeing improved circulation

The appropriate interpretation depends on the specific omega-3 dose, formulation, population, and clinical outcome studied.

Is Krill Oil Safe?

Krill oil is generally used as a source of marine omega-3 fatty acids, and adverse effects reported with omega-3 supplements are often mild.

Possible side effects of omega-3 supplements can include:

• Unpleasant taste or aftertaste
• Heartburn
• Nausea
• Stomach discomfort
• Diarrhea
• Headache

This is important because older marketing claims sometimes state that phospholipid-containing krill oil cannot cause reflux or “fishy burps.” That cannot be guaranteed.

What About Shellfish Allergy?

Krill are crustaceans.

People with a known crustacean shellfish or seafood allergy should review the complete product allergen information and discuss krill-oil supplementation with an appropriate healthcare professional before use.

An allergy history should not be dismissed simply because the ingredient is presented as a purified oil.

Can Krill Oil Interact With Blood Thinners?

Omega-3 fatty acids can influence platelet biology, especially at higher doses.

Clinical research does not show that usual supplemental omega-3 doses automatically cause clinically significant bleeding in everyone using anticoagulant medication.

However, people who use warfarin or other anticoagulant or antiplatelet medications should discuss omega-3 supplementation with their healthcare professional, particularly when using multiple supplements or higher omega-3 doses.

Do not stop or change a prescribed medication because of information in a supplement article.

Who Should Discuss Krill Oil With a Healthcare Professional?

Additional review is reasonable if you:

• Have a crustacean shellfish or seafood allergy
• Take anticoagulant or antiplatelet medication
• Have a bleeding disorder
• Are pregnant or breastfeeding
• Are preparing for surgery or another medical procedure
• Use prescription medication regularly
• Take several omega-3 or marine-oil supplements at the same time
• Are being treated for cardiovascular disease or abnormal blood lipids

Ingredient Research Is Not Finished-Product Research

This distinction is essential when interpreting krill-oil studies.

A clinical trial may use:

• 1, 2, or 4 grams of krill oil per day
• A specific branded krill-oil ingredient
• A defined EPA and DHA dose
• A particular phospholipid concentration
• A particular astaxanthin amount
• A selected patient population
• A treatment period ranging from weeks to months

Another supplement may provide a different krill oil and a substantially different amount of EPA and DHA.

Unless the exact finished product has been studied in an appropriate human trial, the clinical outcomes from a different krill-oil preparation should not automatically be attributed to that product.

How Much Krill Oil Is in RevitaPlus Beauty Pack?

RevitaPlus Beauty Pack contains a krill-oil softgel as one of six daily supplement components.

The current public Supplement Facts information lists:

• Antarctic Krill Oil — 500 mg
• Total Omega-3s (EPA/DHA) — 200 mg
• Phospholipids — 200 mg
• Astaxanthin — 150 mcg

The same label also lists 200 mg of phospholipids and 150 mcg of astaxanthin.

These label amounts confirm what the product contains. They do not by themselves demonstrate superior absorption, improved heart or brain function, a specific reduction in triglycerides, or a joint-health outcome.

What Should You Look for in a Krill Oil Supplement?

Do not compare krill-oil products using only the largest number on the front label.

Review:

• Total krill oil: How much complete oil is provided?
• Omega-3 content: How much EPA and DHA, or total omega-3 containing EPA/DHA, is actually listed?
• EPA and DHA disclosure: Are they reported separately or only as a combined amount?
• Phospholipids: Is the phospholipid amount disclosed?
• Astaxanthin: Is an amount actually listed rather than simply marketed as present?
• Serving size: Is the amount per softgel or per full daily serving?
• Allergen information: Are crustacean shellfish warnings clearly disclosed?
• Quality testing: Is there batch-specific documentation for identity, contaminants, and other relevant quality specifications? If you want to understand claims such as “lab tested” or “third-party tested,” read our guide to heavy-metal testing, COAs, third-party testing, and supplement quality.
• Other supplements: Are you already taking fish oil, algae oil, or another source of EPA and DHA?
• Evidence match: Does the cited study use the same krill-oil preparation and omega-3 amount?

A larger krill-oil milligram number does not automatically mean a larger EPA+DHA dose, better absorption, or a stronger clinical effect.

The Key Takeaway

Krill oil is a marine source of EPA and DHA with a lipid profile that includes phospholipids and naturally occurring astaxanthin.

Human research suggests that some krill-oil preparations can effectively increase omega-3 status, and certain studies have reported favorable pharmacokinetic results compared with specific fish-oil formulations.

But the evidence should not be reduced to claims that krill oil is always “48% more bioavailable,” bypasses digestion, enters cells directly, eliminates reflux, or allows a lower dose to produce the same clinical result.

Research into blood lipids and joint outcomes is also formulation- and dose-specific, with mixed findings in some areas.

When evaluating krill oil, focus on:

• The actual EPA and DHA or total omega-3 amount
• The phospholipid content
• The specific formulation
• The dose used in the cited study
• The outcome that was actually measured
• Safety and medication considerations

Those details provide a more useful comparison than assuming that all krill oils—and all fish oils—behave the same way.

This article is for general educational purposes and is not a substitute for medical advice, diagnosis, or treatment.