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7 benefits of the powerful antioxidants in krill oil

Written by John Davis

Last updated: November 1, 2022

Krill oil is a source of omega-3 fatty acids much like fish oil. It has many of the same benefits, but extra antioxidant and anti-inflammatory capabilities thanks to two key ingredients: astaxanthin and phospholipids.

These compounds allow krill oil to boost your body’s levels of antioxidants in your blood and fight systemic inflammation.

Looking to leverage these benefits by including krill oil in your supplement stack? Read on to find out how.

Krill oil benefits

1. Krill oil combines omega 3 fatty acids and antioxidants

Krill oil is becoming increasingly popular as a supplement because it combines the health benefits of the omega 3 fatty acids you’d find in fish oil with additional health-boosting power from the phospholipids and the astaxanthin that gives krill oil its distinctive deep red color.

The research on the benefits of krill oil is fairly new, but it appears that krill oil offers many of the same benefits as fish oil, but with some additional perks.

As a source of omega 3 fatty acids, krill oil has all of the associated health benefits you’d get in a fish oil supplement too. These benefits are widely documented and affect a myriad of health conditions.

2. Krill oil could help reduce risk factors for heart disease

Omega 3 fatty acids (and especially their primary active ingredients, DHA and EPA) are associated with a decrease in risk factors for cardiovascular disease, as reported by a 2003 study published by the American Heart Association (1).

3. Krill oil can help improve mental health

There is good evidence for their benefits in mental health too: a review in the Journal of Clinical Psychology in 2006 discussed the various uses of omega 3 fatty acids in the prevention and treatment of depression (2), and other research indicates that it can help prevent cognitive decline in the elderly (3).

The real question is whether krill oil offers any additional or independent benefits beyond those of normal fish oil. Fortunately, there’s a lot of research that can help answer this question.

4. Krill oil may offer benefits that fish oil does not

Some evidence from animal studies is promising. In a 2010 study, researchers experimentally induced rheumatoid arthritis (an inflammatory disease of the joints) in mice (4).

The researchers split the mice into three groups: one which received a krill oil supplement, another group that received a fish oil subject, and a final group that acted as a control.

The researchers found that the krill oil was particularly effective at staving off rheumatoid arthritis in the mice. Because the krill oil reduced markers of inflammation at the cellular level in the mice, the researchers proposed that krill oil has especially effective inflammation-fighting properties.

Further research substantiated these claims in human subjects. In a short two-week randomized trial, a paper published in the Journal of the American College of Nutrition found that volunteers with rheumatoid or osteoarthritis received either a krill oil supplement (300 mg per day) or a placebo to serve as a control group.

The researchers found that blood levels of inflammatory chemicals decreased in the krill oil group when compared to the control group.

Though the duration of this study was short, and longer-term studied would be needed to study the clinical outcome of such an intervention, the evidence is promising that krill oil could be a useful treatment for arthritis and other joint pain related to inflammation.

5. Krill oil has also been found to decrease the symptoms of premenstrual syndrome in women

One study, funded by a company that manufactures krill oil, found that women who took a krill oil supplement over the course of three months experienced fewer symptoms of premenstrual syndrome and had to take fewer over-the-counter pain medication during the course of the study to treat their symptoms (5).

6. Krill oil may also be more effective than an equivalent dose of fish oil when it comes to reducing risk factors for cardiovascular disease

That was the conclusion of a 2004 study in the journal Alternative Medicine Reviews (6). That study split a large population of volunteers into four groups that received low or high doses of krill oil, fish oil, or a placebo.

The researchers followed the subjects for 90 days and studied the change in blood sugar, cholesterol, and blood triglycerides–high levels of any of these are strong risk factors for cardiovascular disease.

The study found that, when delivered at equivalent doses, krill oil resulted in a greater reduction in cholesterol and triglycerides than fish oil.

7. Not all researchers are enamored with krill oil

One study by Stine Ulven and colleagues Akershus University College in Norway studied the differential effects of fish oil and krill oil in human volunteers (7).

They found that neither had a significant effect on several markers of metabolic activity, but they did find that fish oil and krill oil resulted in a similar increase in omega 3 fatty acids in the blood, even though the DHA and EPA content of krill oil was only two-thirds that of fish oil.

This may suggest that krill oil has higher bioavailability than fish oil, meaning that you’ll absorb more of the omega 3 fatty acids from krill oil than an equivalent amount of fish oil.

Krill oil side effects

Krill oil is well-tolerated.Much like its cousin supplement, fish oil, krill oil is extremely well-tolerated. The only side effects that are reported are minor: a trivial number of people report mild gastrointestinal discomfort, and some supplements can cause a transient “fish-like” taste in your throat.

Krill oil has fewer potential contaminants. One of the key benefits of krill oil over traditional fish oil is that there is less concern about PCB and mercury contamination in krill oil, because the krill used to produce it are harvested from very cold, infrequently-travelled antarctic waters.

The level of contamination in these waters is thought to be much less than in the ocean at large. If this is something you’re concerned about, choose a krill oil supplement that is tested for mercury and PCB content.

Krill oil dosage

Because so much of the research on krill oil is funded by the companies that make krill oil supplements, the dosages used in research studies usually reflect the dosage available in the supplement that’s the source of the research funding.

Aim for at least 300 mg of krill oil per day. With that caveat, the research indicates that doses of at least 300 mg of krill oil per day are optimal. However, research on fish oil typically uses higher doses to deliver higher amounts of DHA and EPA to the bloodstream.

Higher doses of 800-1200 mg per day might be best for broad spectrum benefits. Considering this, alongside the excellent safety profile of krill oil, it’s probably a good idea to aim for more like 800-1200 mg of krill oil per day for the best chance of broad-spectrum health benefits.

You can achieve this with one high-dose supplement, or by taking a smaller dose supplement a few times during the day.

Krill oil benefits FAQ

Q: How long does krill oil stay in your system?

A: The omega-3 fatty acids in krill oil stay in your system for a surprisingly long time—the elimination half-life of EPA, one of the primary omega-3 fatty acids, is known to be one to three days.

This means that if you take a dosage of 400 mg today, in 1-3 days your body will still be experiencing an effective dosage of 200 mg; a few days after that, the effective dosage has halved again to 100 mg.

As such, krill oil has a profound and lasting effect on your body; as you take multiple doses over the course of several days, the concentration of krill oil in your body rapidly stabilizes and may stay elevated for up to a week after stopping.

This is good news if you are inconsistent or forgetful with your supplements, because it means that the timing of krill oil doses is not particularly important.

Q: What does krill oil do for you?

A: Krill oil, like any source of omega-3 fatty acids, has good potential for reducing your risk factors for cardiovascular disease, like high blood triglycerides or high cholesterol.

Since omega-3 fatty acids are also used heavily by your brain, krill oil may help preserve cognitive function as you get older. Another avenue that is even more interesting is the potential for krill oil to be used as a treatment for mental health problems like depression and anxiety.

Research supports a link between higher levels of omega-3s and decreases in the severity of symptoms. Finally, the anti-inflammatory effects of both the omega-3 fatty acids and the astaxanthin in krill oil may help with joint-related pain from arthritis.

Q: How much krill oil should you take to lower triglycerides?

A: Research supports a krill oil dosage of at least one gram per day, and up to four grams per day to decrease blood triglycerides.

One study actually tested one, two, three, and four grams of krill oil per day in an attempt to establish the optimal dose of krill oil when it comes to decreasing blood triglycerides, but there was too much inter-individual variability to establish strong dosing recommendations (8).

The study did, however, find a significant group effect of krill oil on triglyceride levels, indicating that the krill oil did have the intended effect.

Another study successfully used three grams per day (9), so based on these studies, one to three grams per day seems to be an effective dosage to reduce blood triglycerides.

Q: How can you tell if krill oil is rancid?

A: Krill oil is particularly prone to oxidation, perhaps due to differences in the fat composition included in krill oil versus fish oil. One study found that 50% of omega-3 products contained levels of oxidation above the voluntary limits set by supplement companies (10).

Unfortunately, it’s hard to tell by look or smell whether a krill oil supplement has gone rancid. The best indicator, of course, is the expiration date, but the research cited above suggests that krill oil may go bad even a year out from its stated expiration date.

To keep your krill oil from going bad, you can keep the bottle in your refrigerator to slow the rate of oxidation.

Q: Is krill oil vegan?

A: Krill oil is derived from krill, which are crustaceans that you might think of as smaller versions of crabs or lobsters. So no, krill oil is neither vegetarian nor vegan.

It does qualify as pescatarian, however, so if you are just trying to avoid meat, but not fish or crustaceans, krill oil could suit your needs quite well. If you are vegan or vegetarian, you’ll want to opt for a vegan omega-3 supplement instead.

Q: Are there dangers associated with krill oil?

A: In term of health dangers, krill oil poses little risk to your body. There are some side effects associated with krill oil, but they are mild and not a threat to your physical health—just a fish-like taste in your throat, and mild gastrointestinal discomfort.

Theoretically at least, krill oil in high doses poses less of a danger than fish oil when it comes to contaminants. The PCB and heavy metal content of krill oil might be lower because the deep, cold, antarctic waters in which krill oil is harvested do not have as much pollution.

In practice, high-quality fish oil supplements are tested for PCB and heavy metals, so this isn’t a significant concern.

Related: Our best krill oil picks


Krill oil is a natural source of omega-3 fatty acids with an added antioxidant boost from phospholipids and the powerful anti-inflammatory astaxanthin.

It’s a good supplement to consider if you want to combine the wide-ranging benefits of DHA and EPA omega-3 fatty acids with the focused anti-inflammatory and antioxidant capabilities of the extra ingredients found in krill oil.


John Davis

John Davis is a Minneapolis-based health and fitness writer with over 7 years of experience researching the science of high performance athletics, long-term health, nutrition, and wellness. As a trained scientist, he digs deep into the medical, nutritional, and epidemiological literature to uncover the keys to healthy living through better nutrition.