Krill Oil vs. Fish Oil

Krill Oil vs. Fish Oil

Numerous studies have touted the health benefits (as well as some of the potential downfalls) of krill oil, which is made from tiny crustaceans called krill that live near the bottom of the ocean, and fish oil, which is sourced from salmon and various other fish. Both of these marine oils can boast high levels of the two main omega-3 polyunsaturated fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) as well as respectable amounts of alpha-linolenic acid (ALA) and gamma-linolenic acid (GLA).

In addition, these oils have been studied for their benefits in managing health issues ranging from anxiety and attention deficit/hyperactivity disorder to arthritis, diabetes, premenstrual syndrome, heart disease, and Alzheimer’s disease. However, one important question is, which one is better?

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The answer depends on which factors you consider to be important. For example, krill are harvested in huge amounts from the Antarctic, where they are a critical part of the food chain for whales, seals, penguins, and fish. Concerned scientists, other experts, and some consumers have expressed the fear that overharvesting of krill will have a devastating impact on these marine animals.

According to the Convention on the Conservation of Antarctic Marine Living Resources (CCAMLR), fishing for krill is limited to certain areas of the Southern Ocean and conservation measures are in place. If you buy krill oil, you may want to ensure it comes from an environmentally responsible source.

Health Benefits

Now let’s consider health issues. Fish oil and krill oil have been lauded for their ability to protect the heart and cardiovascular system. In a face-off between the two oils in a recent animal study appearing in the European Journal of Nutrition, the authors noted that while both fish oil and krill oil had somewhat differing effects on fat metabolism and inflammation, overall they were “comparable sources” of omega-3s. In a clinical study sponsored by a krill oil manufacturer, a comparison of krill oil versus fish oil in 120 patients for 3 months revealed that the krill oil was better than fish oil in improving levels of triglycerides and cholesterol.

People with arthritis frequently turn to fish oil for symptom relief and numerous studies indicate the omega-3s can be effective. Case in point is a recent meta-analysis of ten trials that involved 370 patients with rheumatoid arthritis. The reviewers concluded that taking more than 2.7 grams of omega-3s daily for three months reduced the use of anti-inflammatory drugs among patients and also resulted in a trend toward less morning stiffness, inflammation, and other symptoms of rheumatoid arthritis.

But how about krill oil? Only a few studies have investigated this relationship, and the results have been promising. In one study of a rheumatoid arthritis model in mice, the authors reported that krill oil “may be a useful intervention strategy” against inflammatory arthritis.

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Side Effects and Safety

Both fish oil and krill oil can cause bloating, gas, flatulence, nausea, diarrhea, and stomach cramping. If you want to avoid the fishy burp, then krill oil should be your choice, according to Dr. Andrew Weil, who also votes for krill oil being better absorbed. Anyone who has a shellfish allergy should avoid krill oil because it contains the shellfish allergen tropomyosin.

How about safety? Contamination with mercury and other toxins such as polychlorinated biphenyls (PCBs) is a concern when buying fish oil supplements, but is the same true for krill oil? Because of where they live, their size, and their spot on the food chain, krill are much less likely to be contaminated than are fish.


Which oil is better absorbed by the body? The jury appears to still be out on this question. Fish oil and krill oil are structured differently, which means the body responds to them in different ways. While the omega-3s in fish oil are mainly associated with triglycerides, those in krill oil are bonded with both triglycerides and phospholipids. Because triglycerides and phospholipids are digested in different ways, their bioavailability in the body may differ. So far animal research has indicated fish oil is better digested while a clinical study has suggested krill oil is more bioavailable.

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So which one is better, fish oil or krill oil? Until more data have been collected, the answer seems to be up to you. Of course, if you are a vegetarian or vegan who wants nothing to do with either one, then an algae source of the omega-3s may be your choice!

Photo Credit: jcoterhals

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Deborah is a freelance health writer who is passionate about animals and the environment. She has authored, co-authored, and written more than 50 books and thousands of articles on a wide range of topics. Currently, she lives in Tucson, Arizona.