Krill oil is a supplement that is rapidly gaining popularity as an alternative to fish oil.

It is made from krill, a type of small crustacean consumed by whales, penguins and other sea creatures.

Like fish oil, it is a source of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), types of omega-3 fats found only in marine sources. They have important functions in the body and are linked to a variety of health benefits (1, 2, 3, 4).

Therefore, it’s a good idea to take a supplement containing EPA and DHA if you don’t consume the recommended eight ounces of seafood per week (5).

Krill oil is sometimes marketed as being superior to fish oil, though more research on that is needed. Regardless, it may have some important health benefits.

Here are six science-based health benefits of krill oil.

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Both krill oil and fish oil contain the omega-3 fats EPA and DHA.

However, some evidence suggests that the fats found in krill oil may be easier for the body to use than those from fish oil, since most omega-3 fats in fish oil are stored in the form of triglycerides (6).

On the other hand, a large portion of the omega-3 fats in krill oil can be found in the form of molecules called phospholipids, which may be easier to absorb into the bloodstream (6).

A few studies found that krill oil was more effective than fish oil at raising omega-3 levels, and hypothesized that their differing forms of omega-3 fats might be why (6, 7).

Another study carefully matched the amounts of EPA and DHA in krill oil and fish oil, and found that the oils were equally effective at raising levels of omega-3s in the blood (8).

More research is needed to determine whether krill oil is actually a more effective, bioavailable source of omega-3 fats than fish oil.

Summary Krill oil is an excellent source of healthy fats. The omega-3 fats in krill oil may be easier to absorb than those in fish oil, but more studies are needed to say for sure.

Omega-3 fatty acids like those found in krill oil have been shown to have important anti-inflammatory functions in the body (9).

In fact, krill oil may be even more effective at fighting inflammation than other marine omega-3 sources because it appears to be easier for the body to use.

What’s more, krill oil contains a pink-orange pigment called astaxanthin, which has anti-inflammatory and antioxidant effects (9).

A few studies have begun to explore the specific effects of krill oil on inflammation.

One test-tube study found that it reduced the production of inflammation-causing molecules when harmful bacteria were introduced to human intestinal cells (9).

A study of 25 people with slightly raised blood fat levels found that taking 1,000-mg supplements of krill oil daily improved a marker of inflammation even more effectively than a 2,000-mg daily supplement of purified omega-3s (10).

In addition, a study of 90 people with chronic inflammation found that taking 300 mg of krill oil daily was enough to reduce a marker of inflammation by up to 30% after one month (11).

Although there are only a few studies investigating krill oil and inflammation, they have shown potentially beneficial results.

Summary Krill oil contains inflammation-fighting omega-3 fats and an antioxidant called astaxanthin. Only a few studies have specifically investigated the effects of krill oil on inflammation, but they have all found beneficial effects.

Because krill oil seems to help reduce inflammation, it may also improve arthritis symptoms and joint pain, which often result from inflammation.

In fact, a study that found krill oil significantly reduced a marker of inflammation also found that krill oil reduced stiffness, functional impairment and pain in patients with rheumatoid or osteoarthritis (11).

A second, small but well-designed study of 50 adults with mild knee pain found that taking krill oil for 30 days significantly reduced participants’ pain while they were sleeping and standing. It also increased their range of motion (12).

Additionally, researchers studied the effects of krill oil in mice with arthritis. When the mice took krill oil, they had improved arthritis scores, less swelling and fewer inflammatory cells in their joints (13).

While more studies are required to support these results, krill oil appears to have good potential as a supplemental treatment for arthritis and joint pain.

Summary Several animal and human studies have found that taking krill oil supplements helps improve joint pain and arthritis symptoms, though more studies are needed.

Omega-3 fats, and DHA and EPA specifically, are considered heart-healthy (2).

Research has shown that fish oil may improve blood lipid levels, and krill oil appears to be effective as well. Studies have shown it may be particularly effective at lowering levels of triglycerides and other blood fats (2, 14, 15, 16, 17).

One study compared the effects of krill oil and purified omega-3s on cholesterol and triglyceride levels.

Only krill oil raised “good” high-density-lipoprotein (HDL) cholesterol. It was also more effective at decreasing a marker of inflammation, even though the dosage was much lower. On the other hand, the pure omega-3s were more effective at lowering triglycerides (10).

A recent review of seven studies concluded that krill oil is effective at lowering “bad” LDL cholesterol and triglycerides, and may increase “good” HDL cholesterol, too (17).

Another study compared krill oil to olive oil and found that krill oil significantly improved insulin resistance scores, as well as the function of the lining of the blood vessels (18).

More long-term studies are needed to investigate how krill oil affects the risk of heart disease. But based on the evidence so far, it seems effective at improving certain known risk factors.

Summary Studies have found that krill oil, like other sources of omega-3 fats, may be effective at improving blood lipid levels and other risk factors for heart disease.

In general, consuming omega-3 fats may help decrease pain and inflammation (19).

Several studies have found that taking omega-3 or fish oil supplements can help decrease period pain and symptoms of premenstrual syndrome (PMS), in some cases enough to decrease the use of pain medication (20, 21, 22, 23, 24).

It appears that krill oil, which contains the same types of omega-3 fats, may be just as effective.

One study compared the effects of krill oil and fish oil in women diagnosed with PMS (25).

The study found that while both supplements resulted in statistically significant improvements in symptoms, women taking krill oil took significantly less pain medication than women taking fish oil (25).

This study suggests that krill oil may be at least as effective as other sources of omega-3 fats at improving PMS symptoms.

Summary Several studies have found that omega-3 fats may help improve period pain and PMS. So far only one study has investigated the effects of krill oil on PMS, but the results were promising.

Taking krill oil is a simple way to increase your EPA and DHA intake.

It’s widely available and can be purchased online or at most pharmacies. The capsules are typically smaller than those of fish oil supplements, and may be less likely to cause belching or a fishy aftertaste.

Krill oil is also typically considered to be a more sustainable choice than fish oil, because krill are so abundant and reproduce quickly. Unlike fish oil, it also contains astaxanthin.

Unfortunately, it also comes with a significantly higher price tag.

Health organizations typically recommend an intake of 250–500 mg per day of DHA and EPA combined (26).

However, more studies are needed before an ideal dosage of krill oil can be recommended. Be sure to follow the package instructions or discuss it with your doctor.

It is not recommended to exceed 5,000 mg of EPA and DHA combined per day, from either diet or supplements (26).

Finally, keep in mind that some people shouldn’t take krill oil without consulting their doctors. This includes anyone taking blood thinners, people preparing for surgery or women who are pregnant or breastfeeding (4).

This is because omega-3 fats can have an anti-clotting effect at high doses, although current evidence suggests this may not be harmful. Krill oil has not been studied for safety during pregnancy or breastfeeding.

You should also avoid taking krill oil if you have a seafood allergy.

Summary Krill oil capsules are widely available and tend to be smaller than fish oil capsules. Be sure to follow the dosage recommendations on the package.

Krill oil is rapidly gaining a name for itself as an alternative to fish oil.

It may offer unique benefits such as a smaller dosage, antioxidants, sustainable sourcing and fewer side effects.

Whether it truly has superior qualities to fish oil remains to be seen, and more studies are needed to clarify its health effects and ideal dosage.

However, the evidence so far suggests that krill oil is an effective source of omega-3 fats that offers several science-based benefits.