Fish oil or Krill oil: What to choose?

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Fish oil or Krill oil: What to choose?

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Fish oil or Krill oil. What to choose is the question that you may ask when choosing a supplemental source of omega-3. This article deals with this question based on current studies on krill oil and how different it is from fish oil.

Besides olive oil, fish oil is becoming an increasingly popular fat of choice among health-conscious and fitness enthusiasts. Fish oil is consumed because it contains omega-3 polyunsaturated fatty acid (PUFA) that has many health benefits. 

The most studied omega-3 types are eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). 

American Heart Association recommends taking 2 servings of oily fish per week. This provides 250 to 500 mg of DHA and EPA per day (1).

People who don’t like to consume fish, take fish oils as a nutritional supplement. These supplements are a good option because they are free of contaminants and toxins such as mercury. And many come in natural flavors without any fishy aftertaste.

Fish is becoming a limited resource of omega-3 due to an increase in demand,  overfishing, conservation, and regulation. For this reason, people are looking for alternative sources of healthy PUFA (2).

Krill oil or Fish oil

Krill oil is a source of omega-3 like fish oil

Krill oil is becoming a popular alternative to fish oil. Krill oil comes from Antarctic krill (Euphausia Superba). These are the most abundant animals in the Antarctic waters. 

Krills are one of the major food sources of whales, seals, squid, fish, and seabirds. Antarctic krill are small in size and resemble shrimps (3).

They have a total fat content between 12–50%. The EPA content is between 4.5% to 25.3% whereas DHA ranges between 2.1 and 24.3% of total fatty acids. The percentage depends on age, sex, food, and other biological factors (4,5).

Since they have adequate amounts of omega-3, it makes them an ideal source of omega-3. 

Krill are abundant in Antarctica
Krill are the most abundant animals of Antarctica waters

Difference between Fish oil and Krill oil

There are several key differences between krill oil and fish oil. These differences may determine if you want to go for fish oil or krill oil when choosing an omega-3 supplement.

Fatty acid chemical composition

The chemical composition of krill oil is different from fish oil. 

Krill oil composition is diverse. It is composed of phospholipids (PL), triacylglycerols (TAG), diacylglycerols (DAG), monoacylglycerols (MAG), and free fatty acids (FFA) (6).

Much of Krill oil EPA and DHA is linked to phospholipids (approx. 50%) especially phosphatidylcholine. It also has triglycerides (30-40%). 

On the other hand, Fish oil EPA DHA is linked to triglycerides and does not contain any phospholipids (7,8).

The composition of krill oil and fish is different. This difference in the composition of oils could have significant outcomes in terms of absorption and bioavailability as well as overall health benefits of these omega-3 oils.

oily fish is source of fish oil
Oily fish is the source of fish oil

Fatty acid in krill oil is absorbed better

The presence of phospholipids could enhance krill oil absorption because the cell membrane is made up of phospholipids and thus has a greater affinity for krill oil. 

Although studies are limited, EPA and DHA in phospholipid form (krill oil) appear to be readily absorbed compared to EPA and DHA in triglyceride form (fish oil) (9).

Animal research shows that levels of DHA in the brain were significantly increased with krill oil compared to fish oil (10).

The bioavailability (absorption) of omega-3 PUFA is increased with krill oil compared to fish oil (11).

The same amount of krill oil and fish oil were consumed but increased omega- 3 PUFA and reduced omega-6 to omega-3 ratio were observed after krill oil consumption compared to fish oil intake (12).

Current albeit limited research shows that krill oil phospholipid composition is a distinguishing feature that allows a greater bioavailability (absorption) of omega-3 fatty acids compared to fish oil.  

Krill oil may provide stronger health benefits

Like fish oil, krill oil is efficient in lowering the risk of cardiovascular disease and inflammation (13, 14).

This is the reason, krill oil could potentially be more efficient in conferring health benefits.

In animal studies, a similar amount of EPA+DHA produced a stronger effect against metabolic syndrome with krill oil compared to fish oil. 

Lower fat levels were observed in both heart and liver tissues. And inflammation molecules and endocannabinoids were also reduced with krill oil due to better absorption (15).

One study found that only krill oil lowered the fasting glucose levels compared to fish oil. Although, fish oil provided healthy benefits as usual (16).

Research also shows that krill oil when compared to fish oil, worked better in suppressing cholesterol synthesis pathways and regulated more metabolic pathways (17).

Krill oil could potentially be more efficient compared to fish oil in conferring health benefits. however, more human studies are needed to confirm the current knowledge.

Although, the research is limited and in early stages, it shows that krill oil has stronger biological effects compared to fish oil.

Krill oil has Astaxanthin

Studies have shown that antioxidant levels in krill oil are higher than in fish oil (18). In fish oil supplements, astaxanthin is non-existent. 

Astaxanthin is one of the most known components of krill oil. Astaxanthin belongs to the carotenoid family of compounds. The deep red color of the krill oil supplement is due to the presence of Astaxanthin.

Astaxanthin is an antioxidant with strong antioxidant and health potential. Astaxanthin is estimated to be 10 times more antioxidant than Lutein, Zeaxanthin, Canthaxanthin, and β-carotene. It is 100 times more antioxidant than α-tocopherol (Vitamin E form) (19,20).

Astaxanthin is very potent against oxidative stress and inflammation (21,22).

In addition to Astaxanthin, krill oil also contains alpha-tocopherol and other vitamins (23) but they may present in very small quantities or even be removed during the extraction/purification process. 

The krill oil astaxanthin is a strong antioxidant that is not present in fish oil. 

Krill oil and fish oil Cost and Availability 

Krill oil is available in lower concentrations compared to fish oil. 

For example, krill oil concentration found in the market may range from 45 to 200 mg per softgel but the fish oil concentration ranges from 300 to 2250 mg per softgel.

When cost per mg is considered krill oil a more pricey compared to fish oil (24).

ConsiderationsFish oil Krill oil
Fatty acid compositionTriglycerides (TGs)Phospholipids (PLs)
Antioxidant Less More

What to choose?

Krill oil and fish oil are both known to contain beneficial omega-3 fatty acids. 

Both oil types have been shown to have health benefits that can protect against oxidation and inflammation. 

The chemical differences between krill oil and fish oil exist. Studies show that krill is absorbed better and has the antioxidant Astaxanthin. 

Currently, limited studies on krill oil support the idea that krill oil may provide stronger health effects.

If you have already experienced benefits from fish oil and cost is not an issue, krill oil can be a good alternative and may present better health benefits compared to fish oil. Some supplements offer a mix of krill oil and fish oil which can be an excellent option as you get the best of both of these sources.