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A Comparison of Krill and Fish Oils: Is One Better Than the Other?

Kim is an RN and author of the book "360 Health: Your Guide to Cancer Prevention, Healing Foods, & Total Body Wellness."


Essential Fatty Acids

Why do people take fish oil or krill oil? Because both contain Essential Fatty Acids (or EFAs). EFAs are long-chain polyunsaturated fats that are "essential" because our bodies do not manufacture them, and they must be obtained from outside sources. The two main EFAs are Omega 3s and Omega 6s.

A healthy balance of EFAs is needed for healthy hormone production and thyroid function; for cell membranes; for brain function; for cardiovascular health (think cholesterol and triglycerides); for inflammation reduction; and for healthy skin and hair ... to name a few.

The typical Western diet has an overabundance of Omega 6s. They are found in things like highly processed corn oil, soybean oil, sunflower oil, and nuts and seeds. These foods, especially the oils, are found in just about any packaged, convenience food. There is no lack of Omega 6s in most people's diets.

The recommended ratio of Omega 6 to Omega 3 is 2:1. The American diet has more like a 10:1 ratio or even higher. A diet high in Omega 6s is directly attributed to inflammation and disease.

To balance out the high consumption of Omega 6s, it is important to get adequate amounts of Omega 3s. These are much less prevalent in the Western diet. In foods, Omega 3s are found largely in seafood, and to a lesser extent, in foods like flax seed, hemp, chia, and walnuts. Many choose to use supplements to gain enough essential Omega 3s, however.

The important forms of Omega 3 are EPA and DHA. These are ONLY found in fish and seafood (and marine algae). The form of Omega 3s in nuts and seeds is ALA, which must be converted in the body to become EPA and DHA. But this doesn't happen easily or as effectively.

So let's look at a couple of the supplements that contain biologically-ready forms of EPA and DHA: fish oil and krill oil.


How Are Fish Oil and Krill Oil Made?

Fish oil is derived typically from the tissues of oily fish like salmon, herring, mackerel, anchovies, and sardines through a process of heating, centrifuging, and separating the solids and water from the oily parts of the fish. Impurities are then removed and anti-oxidants added.

Krill are tiny shrimp-like creatures living in the world's oceans. They feed on phytoplankton, and are thus at the bottom of the aquatic food chain. Antarctic krill tend to be the coveted species for manufacturers because of the Southern Ocean's pure waters and the harvesting techniques. High quality krill oil is made by freezing the krill immediately upon harvest and then using a cold-vacuum extraction process to obtain the oils. This ensures that none of the nutritional value is lost upon degradation.


Pro Krill Oil Arguments

Proponents of krill oil list a few unique qualities that are lacking in fish oil.

  • Astaxanthin: Krill oil naturally contains a powerful antioxidant called astaxanthin. Astaxanthin inherently protects the fats from oxidizing and becoming rancid. It is anti-inflammatory. It is also responsible for giving the supplement a reddish hue.
  • Phospholipids: The Omega 3s in krill oil are attached to phospholipids, whereas in fish oil, they are attached to triglycerides. Phospholipids (and the accompanying Omega 3s) are readily absorbed by the body because the cell walls in the human body are made from phospholipids. Arguably, krill is more "bioavailable" since fish oil is bound to triglycerides that are not as easily assimilated by the body. Because of the better absorption, less krill oil may need to be taken than fish oil.
  • Purity: Krill, being at the bottom of the food chain and eating only plants, do not have the same contaminants that larger fish contain. Mercury and other toxins are not present in krill. They are also mainly harvested from cleaner waters off of Antarctica.
  • Less GI Upset: Krill oil is typically better tolerated. It lacks the "fishy burps" that fish oil supplements are known to cause.
  • Sustainability: Krill are the largest biomass in the world. Only 1-2% of the krill population is harvested every year. The krill population is monitored by The Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR). The Marine Stewardship Council (MSC) certifies that harvesting is done in compliance with strict sustainability criteria to avoid overfishing.
  • Help with Arthritis: In this one study, 300 mg daily was found to alleviate joint stiffness, inflammation, and pain associated with arthritis after only 7 days with major improvements after the 14 day mark.
  • Improvement in Hyperlipidemia: In a study of 300 people given daily doses of krill oil over a 12 week period (versus a placebo group), those given krill had a statistically significant reduction in serum triglycerides and also did not increase LDL levels of cholesterol.


Pro Fish Oil Arguments

Proponents of fish oil claim that it is vastly superior to krill oil.

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  • Higher Omega 3 Content: The concentration of EPA and DHA in fish oil is much greater. Fish oil contains around 30% EPA and DHA. Krill oil only contains around 14% EPA and DHA.
  • Less Costly: Fish oil supplements are much less expensive than krill oil, especially given that one might presumably need to take more krill oil than fish oil to get the same Omega 3 content.
  • More Research: There are literally thousands of studies and reviews of fish oil supplements and their benefits. There are only a handful of studies on krill oil because it is newer to the market. Fish oil's efficacy and reliability are much better documented.
  • Known Cardiovascular Benefits: Although krill oil may also give some of these same benefits, fish oil has been proven to help with various body systems. Fish oil can help support healthy cholesterol and triglyceride levels. It also seems to surpass krill oil in cardiovascular support by reducing inflammatory cytokines.
  • Hormonal and Brain Help: Fish oil can reduce adrenal stress hormone production. It is also known for helping to stabilize moods by regulating serotonin. The abundance of EPA and DHA in fish oil also have been linked to better brain function. In a study of Alzheimer's patients, those taking fish oil scored higher on cognitive memory tests than those not taking fish oil. DHA especially is also linked with positive brain development for infants and children.
  • Less Metabolic Syndrome: Fish oil has been shown to decrease the incidence of metabolic syndrome. Metabolic Syndrome is a cluster of risk factors including abdominal obesity, elevated blood sugar, hypertension, elevated triglycerides and low-density lipoproteins (LDLs).
  • Bone and Skin Health: Due to its highly anti-inflammatory nature, fish oil can improve skin texture and overall skin health. It is also associated with reduced inflammation in joints. Studies have also shown bone density may be aided by consumption of fish oil.

Which Supplement Should I Take?

Both fish oil and krill oil offer advantages. Depending on the consumer's specific needs, one may be a clear choice over the other. For example, since krill oil seems to trump fish oil in joint health, specifically in regard to rheumatoid arthritis, someone with RA might choose krill. On the other hand, if someone has known cardiovascular disease or a family history of it, they may choose fish oil since many more studies have associated fish oil with cardiovascular health.

In doing research for this article, quite a few doctors and authors suggested actually taking both. Krill oil may be more easily absorbed and offers the added anti-inflammatory component of astaxanthin. Fish oil has significantly more EPA and DHA per pill, so one can get a "fuller dose" with less pills and less cost. A combination of the two may be the most beneficial formula.

Video Encouraging Use of Both

What to Look For in a Supplement

Krill oil should come from the Antarctic region which provides the cleanest and purest supplement. It should be "cold-pressed" so that oxidation and degradation do not occur. The Marine Stewardship Council's seal of approval is also important to ensure the krill was correctly harvested. Anyone with a shellfish allergy should NOT take krill oil.

Fish oil should also meet certain criteria. According to Chris Kresser, an integrative medicine practitioner, one should look for the following things to ensure a high quality fish oil: purity, freshness, potency, nutrients, bioavailability, sustainability, and cost. The supplements should meet international standards for contaminants. They should have an adequate amount of DHA and EPA. The fish oil should be harvested in a sustainable way, not contributing to the overfishing dilemma. More expensive supplements are not always better.

The consumer, whether taking krill oil or fish oil, should always read labels and inform their doctors prior to beginning any supplement regimen.

Fish Oil

Krill Oil


This content is accurate and true to the best of the author’s knowledge and does not substitute for diagnosis, prognosis, treatment, prescription, and/or dietary advice from a licensed health professional. Drugs, supplements, and natural remedies may have dangerous side effects. If pregnant or nursing, consult with a qualified provider on an individual basis. Seek immediate help if you are experiencing a medical emergency.

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