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Krill Oil vs Fish Oil Review

Fish oil is one of the most popular nutritional supplements used today, and has a lot of well studied benefits which are recognised by health professionals. Krill oil has only come onto the market recently. Whilst it has not been studied as extensively, many believe it to be superior to fish oil, and it is becoming a popular alternative source of omega-3 fatty acids.

Krill oil is sourced from Antarctic krill. Euphausiacea superba is a small crustacean which grows up to 6cm in size. It is an extremely abundant species and it is estimated that the oceans contain 500 million tonnes of krill, twice the mass of all the humans on earth. Krill is near the bottom of the food chain. It eats algae and plankton and in turn is fed upon by marine mammals, fish and birds. It is harvested from the Southern Ocean and from the waters around Japan. Fish oil is produced from inedible bycatch, by-product from fish processing plants, and occasionally fish is caught specifically for oil manufacture. Much of the world's fish oil comes from Northern Europe and South America.

Which oil is best? Are they different? We take a look at some of the attributes of each.

Krill Oil vs Fish Oil for Omega 3

What are Omega-3 Fatty Acids?

Omega-3 fatty acids are a type of polyunsaturated fat needed by the body to properly function. Along with the omega-6 group they are known as essential fatty acids because the body cannot make its own, so they must be taken in through diet or supplementation. There are three omega-3 fatty acids of importance to human health. Alpha Linoleic Acid (ALA) is the shortest omega-3 fatty acid, and the human body has a limited ability to produce the longer-chained, more biologically active eicosanoids, Eicosapentaenoic Acid (EPA) and Docosahexaenoic acid (DHA) using ALA as a starting point. Because this is an inefficient reaction, all three of these omega-3 fatty acids should be consumed in a well balanced diet.  Both fish and krill oil are rich in EPA and DHA.

Why do we need Omega-3 Fatty Acids?

Long chain omega-3 fatty acids such as EPA and DHA are involved in a diverse array of important processes including:

  • Maintaining cell membrane structure and assisting in cell division.
  • Maintaining healthy skin and hair
  • Inflammation
  • Blood clotting
  • Lipid Metabolism
  • Energy Production
  • Regulation of neurotransmitters
  • Production of hormones
  • Assisting nerve and brain function

The best source of omega-3 fatty acids is seafood, including oily fish and krill. Other, less concentrated sources include flaxseed, some nuts, eggs, and some algae. The ratio of ALA, DHA and EPA differs between sources. Plant based sources in paticular are considered lower in quality becausethey are made up of greater amounts of ALA and fewer of the longer chain fatty acids, which are the forms approved by the US FDA for medical claims.

Recommended Daily Intake for Omega-3 Fatty Acids

The Recommended Daily Intake (RDI) for omega-3s is expressed as the amount of DHA and EPA present, rather than as a total amount. As well as measuring what are considered to be the active ingredients, this accounts for the biological variation between omega-3 sources. Doses as low as 250mg are recommended for basic health maintenence. The American heart foundation recommends 1g per day as therapeutic in lowering blood fats, and doses of up to 6g per day are recommended to help inflammatory conditions, such as arthritis. These doses include what we consume in our food.

Krill Oil vs Fish Oil for Joints, Inflammation, Arthritis & Depression

Firstly, for general health. Almost as important as the amount of omega-3 consumed, is the ratio in which it is taken with omega-6 fatty acids. A normal western diet contains on average a 1:15 ratio of omega-3:6. Many believe an optimal ratio is in the range of 1:1-1:4. Omega-3 and 6 fatty acids compete for processing within the body, and in general terms, the products of omega-6 are pro-inflammatory, whereas omega-3 have the opposite effect.

Secondly, fish oil has shown effectiveness in the treatment of many specific conditions like cardiovascular disease, arthritis and joint inflammation, and depression.

What are the differences between Fish Oil and Krill Oil?

While fish and krill oils have many similarities and fill the same niche in the supplement market there are many points of difference on which fish and krill oils can be compared.

Krill Oil vs Fish Oil Dosage & Bioavailability

The most talked about difference between these two oils is the chemical form in which the omega-3 fatty acids are stored. In fish oil, DHA and EPA, the important fatty acids, are predominantly stored as fatty acid esters, whereas krill oil is mainly composed of phospholipids and free fatty acids, which are thought to be easier to digest and absorb. There has been some research looking into this. One small study saw a trend toward greater absorbtion of omega-3s from krill oil, but it was not statistically significant (2), while another study reported equivalent metabolic effects from equal amounts of krill and fish oil. This is interesting, firstly because krill oil contains less EPA and DHA on a percentage basis than fish oil, and secondly, because the results imply that the fatty acids in krill oil were better absorbed - attributes which, in this study, cancel each other out (3). These results are promising, and would become clearer with more extensive study.

Krill Oil vs Fish Oil Benefits

As the study before told us, fish oil is made up of about 80% DHA and EPA, and krill oil 50% (2). Can the other ingredients in these oils tip the balance in favour of one source or another?

Krill oil is lauded for its antioxidant properties. The major antioxidant present in krill oil is the bright red carotenoid pigment astaxanthin. Human studies have shown that astaxanthin can protect against oxidative stress, and lessen inflammation and cardiovascular disease, however these effects are only seen at doses of about 5mg per day (5). Krill oil contains minute amounts of astaxanthin – about 0.01%, which means a generous daily dose of 1g would provide only one fiftieth of what is considered a low therapeutic amount. This is not something that distinguishes krill oil as a superior supplement.

Many krill oil preparations are supplemented with astaxanthin, and this antioxidant could just as easily be added to fish oil. Fish oil is naturally high in trace elements Iodine and Selenium, and both krill and fish oil are high in vitamin A, all of which have antioxidant properties. The phospholipid structure of fatty acids in krill oil is thought to have other benefits in addition to more efficient absorption. Fish oil is only 1-1.5% phospholipid, as opposed to 30-40% in krill oil, and there is evidence for the role of phospholipids in human health (4).

Krill Oil vs Fish Oil Processing and Quality

Krill oil is often marketed as a safer and purer product because if comes from clean Antarctic waters, and krill is lower down the food chain than fish. There is a misconception that fish oil is high in accumulated toxic compounds like mercury and other heavy metals, polychlorinated biphenyls (PCBs) and dioxins. This is not the case - the presence of toxins in both fish and krill oil is monitored by organisations like the TGA in Australia. Additionally, an international fish oil standards committee has been formed to oversee production and quality worldwide. Studies have shown modern fish oil supplements are just as safe, if not safer, than consuming oily fish (6).

One of the biggest problems with polyunsaturated fatty acids, like those present in both fish and krill oil, is their tendency to oxidise and become rancid. There is a lot of conflicting opinion on which is the more stable oil. The major sources of fish oil can be up to 80% fat – this high concentration, along with the presence of antioxidants like selenium and iodine, accumulated through the food chain, is thought to prevent oxidation, meaning the fish does not need to be processed immediately.

It is often said that the major contribution of natural astaxanthin to krill oil is its role in delaying oxidation. Nonetheless, krill, at about 5% fat, needs to be frozen, kept alive, or processed immediately to prevent the oil from going bad before it is extracted and stabilised. What does this mean? Even if both oils are processed to retain 100% of their efficacy, a lot more krill is required, and must be stored under much more stringent conditions than fish. This is a big reason why, despite being one of the most abundant creatures on earth, oil from krill can be a lot more expensive than fish oil. Many claims are made, particularly by the makers of krill oil, that it is vastly more stable than fish oil. A popular consumer review organisation found that both oils are relatively stable once on the shelf (7). Most are blended with antioxidant stabilising agents such as vitamin E and rosemary oil.

Krill oil vs Fish oil Study

It is known that different blends of fish oil from different species can exert different effects on human health due to different ratios of various fatty acids. As these two supplements are similar, it might seem like the findings that apply to fish oil are also true of krill oil, but this is not the case. The data concerning fish oil and krill oil must be considered seperately.

Although many properties of krill oil are exciting and hint at benefits over and above that which fish oil can deliver, there is just not enough research to support many of these claims.
Fish oil is one of the best studied nutritional supplements available. It is very well known for having proven effect on a number of diseases. It is so effective that it is often prescribed by doctors in place of pharmaceutcal medication.

There are many areas in which the preliminary data on krill oil agrees with that of fish oil. A good example of this is that neither oil shows any appreciable effect on diabetic symptoms, such as blood glucose, insulin levels or other diabetic markers in humans. It also has no influence on body weight.
Fish oil has a remarkable effect on cardiovascular disease, where it can lower triglyceride levels and blood pressure in hypertensive people. This is an interesting area, as the small amount of research that has been done in humans suggests krill oil has a similar effect on blood triglycerides, but a very different effect on other blood lipids.

The small amount of evidence so far also indicates that krill oil might work differently to fish oil in treating inflammation. Fish oil has been long known for its ability to improve joint health by reducing inflammation, but not for its effect on C-reactive  protein (CRP), a marker protein that rises in response to inflammation. Early experiments have shown that krill oil is effective in reducing CRP levels in the bloodstream, indicating that these two similar supplements may have different modes of action.
There are also areas where there is not yet any evidence for krill oil's efficacy, such as the treatment of mental health and prevention of cognitive decline, something fish oil is known for.
Such differing results show that the two oils are not interchangeable, although the small number of studies of krill oil do not yet draw a definitive conclusion.

The cause of these differences has not been researched – there are very few direct comparisons of fish oil and krill oil, but two options are the presence of different substances in krill oil, or the phospholipid form of these long chain fatty acids. Phospholipids have known health benefits, and there is some evidence for the role of phospholipids in treating or reversing conditions such as lipid disorders and obesity, arthritis, oxidative damage in athletes, and animal studies show reductions in inflammation, obesity and hepatic steaosis (4).

Krill Oil vs Fish Oil for Bodybuilding

The benefits of Omega-3 fatty acids have been known to bodybuilders for some time. Studies in both animals and humans have shown that it can help in the preservation of lean muscle mass when the body is in a catabolic state, for example, during a cutting cycle, and that it may stimulate muscle growth in healthy adults by enhancing the body's anabolic response to insulin and amino acids (8). Krill oil may have added benefits on top of this. If krill oil does have greater anti-inflammatory properties than fish oil, supplementation could mean smoother recovery from training.The benefits of phosphate-bound fatty acids are also worth considering. There is some evidence that phosphatidylcholine, which is the main form of fatty acid in krill oil, has a detoxifying effect on the liver which can enhance IGF-1 production, and that it may support fat loss.

Krill oil is a very promising nutritional supplement that may work in a different way to fish oil, and is a substance worthy of a great deal more research. Fish oil has a long history of preventing and lessening the symptoms of disease which is backed up by a huge amount of scientific testing.
In spite of their differences, if you want omega-3, you cant go wrong with either of these beneficial marine oils.

(1) Shaikh SR, Edidin M. Polyunsaturated fatty acids, membrane organization, T cells, and antigen presentation. Am. J. Clin. Nutr. 84(6), 1277–1289 (2006).
(2) Schuchardt JP, Schneider I, Meyer H, Neubroner J, Von Schacky C, Hahn A. Incorporation of EPA and DHA into plasma phospholipids in response to different omega-3 fatty acid formulations--a comparative bioavailability study of fish oil vs. krill oil. Lipids Health Dis. 2011 Aug 22;10:145.
(3)Ulven SM, Kirkhus B, Lamglait A, Basu S, Elind E, Haider T, Berge K, Vik H, Pedersen JI. Metabolic effects of krill oil are essentially similar to those of fish oil but at lower dose of EPA and DHA, in healthy volunteers. Lipids. 2011 Jan;46(1):37-46.
(4) Lena Burri, Nils Hoem, Sebastiano Banni, Kjetil Berge. Marine Omega-3 Phospholipids: Metabolism and Biological Activities. Int J Mol Sci. 2012; 13(11): 15401–15419.
(5) Fassett RG, Coombes JS. Astaxanthin, oxidative stress, inflammation and cardiovascular disease. Future Cardiol. 2009 Jul;5(4):333-42.
(6) Stacy E. Foran, MD, PhD; James G. Flood, PhD; Kent B. Lewandrowski, MD. Measurement of Mercury Levels in Concentrated Over-the-Counter Fish Oil Preparations: Is Fish Oil Healthier Than Fish? Arch Pathol Lab Med—Vol 127, December 2003
(7) Fish Oil. - accessed 20/11/2013
(8) Smith GI, Atherton P, Reeds DN, et al. Omega-3 polyunsaturated fatty acids augment the muscle protein anabolic response to hyperinsulinaemia-hyperaminoacidaemia in healthy young and middle-aged men and women. Clin Sci (Lond). 2011;121(6):267-78.

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