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Fish oil is one of the best known and most popular supplements on the market today. fish oil is rich in omega-3 fatty acids, which are essential for good health, and it has a number of well researched benefits that have been recognised by the medical community. Krill oil is a recent addition to the market and it is being touted as having benefits that outweigh those of fish oil.

Fish oil is manufactured from the by products of the seafood industry, including waste material from fish processing and inedible bycatch, while krill oil is extracted from Antarctic Krill, a small crustacean near the bottom of the food chain, and one of the world's most abundant species. It is estimated that the biomass of krill is twice that of all humans on earth, and krill is harvested at sustainable levels from the southern ocean. Both oils have similar attributes, but there are also a number of differences that distinguish fish and krill oils. Let's have a look at both oils.

Fish Oil vs Krill Oil Benefits

Both fish and krill oils are rich in omega-3 fatty acids, which, along with omega-6 fatty acids are considered essential nutrients, because we cannot produce them and must obtain them through the diet. There are three types of fatty acid that are important in maintaining health and wellbeing. Alpha Linoleic Acid (ALA) is the shortest omega-3 fatty acid, and it can be used by the body, to a very limited extent, to produce the two longer, more biologically active omega-3 fatty acids Docosahexanoic Acid (DHA) and Eicosapentaenoic acid (EPA).

The recommended intake and therapeutic dose of omega-3 is based on the levels of these two long chain fatty acids. While a properly balanced diet should feature all three omega-3 fatty acids, care should be taken to ensure sufficient DHA and EPA is being consumed. The best food sources of omega-3 fatty acids include oily fish and krill, flax seeds, some nuts, and algae.

These sources differ in relative ratios of omega-3 types, and in general, aquatic sources are richer in DHA and EPA, while plant sources tend to contain more ALA and are therefore considered lower quality. Long chain omega-3 fatty acids play a diverse variety of roles in the body, and are required for the functioning of a number of different organs and systems.

This includes:

Cardiovascular – Regulation of healthy blood lipid levels, required for normal blood clotting.

Nervous System - supports healthy nerve and brain functioning, and regulates the production of neurotransmitters.

Joints and Inflammation – Reduces inflammation through regulation of the production of inflammatory chemicals within the body.

Endocrine – Used as the starting point for production of a number of hormones.

Cellular – maintains cell membrane structure and assists in cell division.

General – Maintains health of skin and hair.

Fish oil vs Krill Oil - Difference Between Fish Oil and Krill Oil

Both fish and krill oil are rich sources of omega-3 fatty acids, but there are a number of physical differences between the two products. The most significant of these is the way that the omega-3 fatty acids are packaged, which is different in each type of oil.

While fish tend to store DHA and EPA as fatty acid esters, they are stored differently in krill, in the form of phospholipids. Scientists have only performed a small amount of research into the differences between these two types of fat, but it is believed that the phospholipid form of these fatty acids may be absorbed better (1).

Another study showed that krill oil, despite containing lower levels of DHA and EPA, exerts an identical metabolic effect to the equivalent amount of fish oil (2). The authors noted that fish oil contains higher overall amounts of DHA and EPA. This, again, implies that the omega-3 fatty acids in krill oil are better absorbed. It is believed that the phospholipid structure may pass more easily through the gut wall, but more research is required to support these findings (2).

Another factor that many people believe distinguishes between krill and fish oil is the presence, in krill oil, of a poweful antioxidant known as astaxanthin. This carotenoid pigment has been shown to exert a number of beneficial effects in humans, including protection against oxidative stress, reduction in inflammation, and even benefits in the treatment of cardiovascular disease. Unfortunately, astaxanthin is found in krill oil in amounts much lower (about fifty-fold less) than levels which have been found to exert this therapeutic effect (3).  While many krill oil supplements are fortified with additional antioxidants, so are many fish oils, and both types of oil are high in vitamin A, which is a potent natural antioxidant.

Because a fish is higher up the food chain than an algae-feeder like krill, there is an idea that fish accumulate toxins such as mercury, other heavy metals, and chemicals such as PCBs and dioxins. Krill oil is sometimes marketed to capitalise upon these fears. Both fish and krill oil are stringently monitored for contaminants by regulatory organisations, such as Australia's Therapeutic Goods Administration (TGA), who are responsible for ensuring the safety standards of goods such as these, which are available commercially. In addition, an international fish oil standards committee has been formed to ensure a high quality standard is maintained across all producers, regardless of country. Studies have shown that consuming fish oil as a supplement provides the same benefits and is just as safe, if not safer than consuming oily fish (4).

Fish oil vs Krill Oil Study

Fish oil is one of the best studied nutritional supplements on the market, and it has been proven time and time again to have a beneficial effect on many conditions, including cardiovascular health and inflammatory conditions like arthritis. These are the two medical conditions for which it is has official usage recommendations from bodies wordwide, including the Australian Heart Foundation and the American Food and Drug Administration (FDA).

Fish oil and krill oil are similar but not identical. It is tempting to apply the findings for fish oil to krill oil. In many cases, comparing these two supplements will yield similar results, but the small amount of research that has already taken place has shown some Important differences between the two supplements. This means we cannot make assumptions and must consider these two omega-3 rich marine oils seperately. By the same token, some of the early findings have hinted at some very exciting benefits of krill oil over and above what fish oil can deliver, but at this stage, there is not enough research to make any definitive claims.

Fish Oil vs Krill Oil for Cholesterol, Cardiovascular and Heart Health

Some of these interesting findings regard effects on lipid levels in humans. It has been known for a while that fish oil is extremely effective in reducing levels of blood triglycerides, and hypertension, in patients with cardiac disease. Fish oil supplementation is sometimes used by doctors as an alternative to pharmaceutical treatment. Early studies into krill oil's effect on blood pressure and triglyceride levels found similar effects. However, it was also found that fish oil and krill oil have markedly different effects on the levels of other types of blood lipids, which means a lot more work needs to be done to fully explore the effects of krill oil on cardiovascular health (5).

Fish Oil vs Krill Oil for Inflammation, Joint Health and Arthritis

Similarly, it has been shown that krill oil is effective at treating inflammation, but may have a different mode of action to fish oil. It is only early days, but scientists have shown that krill oil reduces bloodstream levels of CRP, or C-reactive protein, a marker of inflammation. Fish oil is widely taken by sufferers of conditions like arthritis to reduce inflammation, but years of study have shown that it eases this condition by a mechanism that does not involve CRP. This indicates that these two substances are likely to combat inflammation through different methods (7).

Fish Oil vs Krill Oil for Cognition and Depression

There are also benefits of fish oil that have not yet been explored in krill, including the important and emerging role of fish oil in the treatment of some forms of cognitive decline and mental illness. While there is speculation, the true cause of these differences is yet to be determined, although an obvious frontrunner is the make up of krill oil, which has up to 40% phospholipid, as opposed to fish oil, which only contains around 1%. There is some evidence for the health benefits of phospholipids in the treatment of conditions like obesity, lipid disorders and oxiative damage. The roles of other substances, such as astaxanthin, that may be present in this new and under-researched omega-3 source also cannot be discounted (6).

While fish oil has proven itself as one of the most best and most versatile supplements on the market, krill oil is new to the market, and only has a small amount of research behind it. What we have seen so far is very promising, and with time it is hoped that we will come to have a full appreciation of the unique properties krill oil has to offer.

(1) 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.
(2)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.
(3) Fassett RG, Coombes JS. Astaxanthin, oxidative stress, inflammation and cardiovascular disease. Future Cardiol. 2009 Jul;5(4):333-42.
(4) 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
(5) 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.
(6) Fish Oil. - accessed 20/11/2013
(7) Kwantes JM, Grundmann O. A Brief Review of Krill Oil History, Research, and the Commercial Market.  Journal of Dietary Supplements, Early Online:1–13, 2014.

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