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BY Bo Martinsen, MD Jan 14, 2016

Fish Oil, Salmon Oil, Cod Liver Oil, Krill Oil: What’s the Difference?

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Today, the omega-3 industry is specializing more than ever. On the supermarket shelf, you don’t just find fish oil any longer, but a broad range of products under that main heading.

As we get a greater selection of omega-3 products, how do you decide what to pick? One helpful method is to consider the source of the oil.

Regular Fish Oil

Norwegian fishing boat
Although many brands imply their fish oil comes from arctic waters in their advertising, most of it actually originates in South America, Africa or China.

Fish oil is in many ways a wide category term. It’s oil made from fish. If you are talking about fish oil, you could mean an oil coming from a particular variety, including cod or salmon. For the rest of this article, however, I’m going to discuss regular fish oil as a specific category, and one that is manufactured in a different way from cod liver and salmon oils.

Where Does Fish Oil Come From?

The great majority of the world’s fish oil is a byproduct of the animal feed industry (1). This includes the capsule products sold at Walgreens and Costco, as well as the fish oil used as a base for pharmaceutical omega-3 oils. The oil comes from anchovy, herring, sardines and mackerel, typically fished off the coast of South America, North Africa or China. While the fish meat gets ground into pellet feed, the oil is multi-purposed. Some of it goes towards fish feed and pet food. The rest is refined and encapsulated for human consumption. As the Norwegian newspaper Aftenposten explained, there’s often no quality control differentiation between the oil destined for people and animals before the refining process (2).

This origin story explains why regular fish oils typically taste and smell bad and often produce ‘fish oil burps’. Since the main goal is to produce fishmeal, the manufacturers have little interest in maintaining the quality of the fish oil. The oil is usually extracted last and often goes rancid within a short period of time. New techniques enable manufacturers to make the oil taste less offensive. However, you can never restore a rancid fish oil back to freshness.

As for the nutritional profile, some of these fish oils have the highest omega-3 content – up to 30% combined EPA/DHA (3). On the other hand, half of the fats are saturated, or the double of what is found in salmon or cod liver oil.

How Much Fish Oil Should I Take Daily?

Depending on the fish oil product, it typically takes 8 to 10 large capsules to get the 3000 mg EPA/DHA omega-3 recommended for getting anti-inflammatory benefits.

Fish Oil Pros

Fish Oil Cons

Contains the most EPA/DHA per oil dose.
Byproduct from the animal feed industry.
Typically rancid.
Half of the fats are saturated.

 

Fish Oil vs. Salmon Oil

Salmon oil sounds good. You visualize a beautiful salmon fillet, and imagine you get the same quality you would if you ate wild caught fish. The reality is not as pretty. Because salmon is an expensive fish, it’s the leftovers – head, intestines and fins – that get turned into the oil, not the fillet. To be fair, those parts of the fish are fine to consume, so no negative comments there.

Most salmon oils, however, come from sea farmed salmon, which nutrition-wise is very different from its wild cousin. The fish delivers the same nutrition it gets, and sea farmed salmon typically gets its omega-3 from pellet feed. But how much omega-3? The problem is, it can be hard for consumers to find out what the farmed fish are fed, especially if the fish comes from a foreign country.

salmon oil vs. fish oil sea farmed vs. wild

Is Sea-Farmed Salmon Better than Wild Salmon?

What we do know is that sea farmed salmon usually contain much more omega-6 (4) and saturated fats than wild salmon (5). In addition, depending on the type of salmon, the EPA/DHA content is relatively low, typically ranging from 8 to 16% of the oil. That means, you would need twice as many salmon oil capsules to get the same EPA/DHA dose found in regular fish oil capsules. As for getting a clinical dose of 3000 mg EPA/DHA, you would need around 20 capsules per day. That low dose also makes salmon oil more costly per omega-3 unit than typical fish oil capsules.

On the plus side, sea farmed salmon oil is often fresher than the wild version because the time from harvesting the fish to processing the oil is shorter.

If you happen to find a salmon oil that comes from wild salmon, the fatty acid balance resembles cod liver oil, but contains less omega-3. In addition, wild salmon oil is often rancid because of the long transportation time and because the fish is often stained with blood, which oxidizes the oil.

Salmon Oil Pros

Salmon Oil Cons

Often fresh because of short time from harvest to processing.
Often made from sea farmed salmon.
Lower in saturated fats than regular fish oils.
Low omega-3 levels compared to other types of fish oils.
More expensive per EPA/DHA dose.

 

Fish Oil vs. Cod Liver Oil

Cod liver oil is the original omega-3 source. Already in the 1700s, doctors were recommending cod liver oil for patients with joint pains, although its rich history dates back further (6). Considered a safe food product, cod liver oil is especially recommended for children and pregnant women in countries like Norway (it’s worth noting, other omega-3 sources do not enjoy the same government-endorsed status) (7).

Part of the reason cod liver oil has been used for so many years is that the oil is easy to extract. The cod liver contains its omega-3 rich oil in small vacuoles. When the oil is extracted, there is limited amounts of rancidity-creating blood present. However, since cod liver oil was historically left in open vats and exposed to heat and oxygen, the poor taste became notorious and limited its popularity. With modern technology and increased focus on freshness, cod liver oil has come a long way. For instance, Omega Cure® cod liver oil is tasteless and can even be used in chocolates or cookies.

Nutritional Benefits of Cod Liver Oil

Cod liver oil is the only omega-3 source that also contains significant amounts of vitamin A and D*. As for the omega-3s, it typically contains around 20% EPA/DHA, and has only half the amount of saturated fats of regular fish oils. To get a clinical dose of 3000 mg EPA/DHA, you would need to consume one tablespoon (15 ml) of oil or 15 capsules.

Of course, not all cod liver oils are alike. While Omega Cure is a fresh, full-spectrum cod liver oil, store-bought cod liver oils are typically highly refined and oxidized (rancid).

Cod Liver Oil Pros

Cod Liver Oil Cons

Long history of medicinal use and safety.
If not manufactured correctly, vitamin A and D content may exceed dietary recommendations.
Can be a good source of vitamin A and D.*
Contains less saturated fats than regular fish oils.
Often comes in liquid, making it easier to get an effective dose.


* The vitamin A and D in modern cod liver oils is unfortunately reduced due to necessary refining. One tablespoon of Omega Cure, for instance, contains only 30% of the daily vitamin A recommended and only 10% of the daily vitamin D recommended.

Krill Oil vs. Fish Oil

Although not derived from fish, krill oil is also a popular omega-3 source. So what’s the difference between krill oil and fish oil?

Like regular fish oils, krill oil is a byproduct from the animal feed industry where the main goal is to make feed for chicken or sea farmed fish. Compared to the above fish oil products, however, krill oil is much harder to extract. The manufacturers typically use solvents to extract the oil. In some cases, the use of these chemicals can have serious consequences. In 2012, for instance, chemicals caused a deadly explosion at one krill oil facility (8).

Nutritional Makeup of Krill Oil

Depending on the product, krill oil typically contains somewhere between 15 to 25% EPA/DHA. Krill oil has become popular because the labels claim you only need one capsule a day. Looking at the research, however, you have to wonder what that one capsule is supposed to be achieving. Even the krill oil manufacturers’ own studies show that you need more than 4 capsules per day to get any meaningful increase of omega-3 in the body (9). And if you look at the amount of EPA/DHA per capsule, it would take more than 20 capsules to reach a clinical dose of 3000 mg EPA/DHA.

Krill Oil EPA/DHA chemical makeup
Krill oil typically contains between 15 to 25% EPA/DHA, albeit it significantly less DHA than EPA.

Is Krill Oil As Good As Fish Oil?

So far, krill oil lacks the scientific support that cod liver oil and fish oil have in spades. The manufacturer’s claim that the astaxanthin antioxidant renders additional benefits has not been proven, nor that the special phosholipid form makes any difference in terms of bioavailability relative to other fish oils (10, 11).

The krill oil manufacturers also struggle with rancidity issues. At the cost of 5 times as much per omega-3 unit than regular fish oil, you’ve got to wonder if krill oil is worth it. Particularly until researchers learn more about its efficacy and safety.

Krill Oil Pros

Krill Oil Cons

The jury is still out on this one.
Byproduct of the animal feed industry.
Solvents are used to extract the omega-3, raising safety questions.
Expensive compared to other omega-3 products.
Not enough studies to support manufacturers’ claims of efficacy at recommended doses.

 

What’s the  Main Message?

Taking a clinical EPA/DHA dose of any of these omega-3 oils should lower triglyceride levels in the blood. However, the manufacturing methods, the freshness factor, and the nutritional profiles of the oil will also impact clinical effects.

In many ways, we should stop talking about omega-3 in general and start clearly attributing the source of the omega-3 oil and the dose in reporting any new study. Right now, it’s as if we are making a judgement about the health benefits of grains, without mentioning whether we’re discussing barley or wheat or quinoa, refined grains or whole grains.

As you go forth looking at different omega-3 supplements, consider the source and what that means for the daily dose you need to consume. And of course, if you have a question, post them in the comments below.

fresh full spectrum fish oil dose omega 3 innovations

References:

1. Halvorsen, Johannessen, Ida and Randi. Vi skal jo selge et produkt’: Oljen er produsert i anlegg som lager dyrefor – i Sør-Amerika.” Aftenposten. May 20, 2008.

2. Halvorsen, Johannessen, Ida and Randi. “Nordmenn kjøpte overpriset fiskeolje fra Sør-America for 285 millioner kroner i fjor.” Aftenposten. May 15, 2008.

3. Omega-3 Fatty Acid, Fish Oil, DHA (docosahexaenoic acid), EPA (eicosapentaenoic acid). WorldHealth.Net. American Academy of Anti-Aging Medicine. December 30, 2005.

4. Hamilton et al. Lipid composition and contaminants in farmed and wild salmon. Environmental Science and Technology. 2005 Nov 15; 39(22):8622-9.

5. Kirkpatrick, Kristin. Fish Faceoff: Wild Salmon vs. Farmed Salmon. Health Essentials. Cleveland Clinic. March 3, 2014.

6. Guy, Ruth.  The History of Cod Liver Oil as a Remedy. The American Journal of Diseases of Children. 1923; 26(2):112-116. doi:10.1001/archpedi.1923.04120140011002.

7. Kosthold for gravide. Helsedirektoratet.no. November 1, 2015.

8. Neptune at fault in deadly plant explosion, CSST rules. CBC News. May 8, 2014.

9. Burri, Lena. Optimizing the Omega-3 Index with Krill Oil. Superba Krill. Aker BioMarine.

10. Daniells, Stephen. Krill and fish oil supplements equally effetive at boosting omega-3 levels, says DSM study. NutraIngredients-USA. September 10, 2015.

11. Salem, Norman and Kuratko, Connye. A reexamination of krill oil bioavailability studies. Lipids in Health and Disease 2014; 13:137. DOI: 10.1186/1476-511X-13-137.

We put a cod liver oil, krill oil, prenatal omega-3 and fish oil capsule to the taste test. Watch what happens next:

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12 thoughts on “Fish Oil, Salmon Oil, Cod Liver Oil, Krill Oil: What’s the Difference?”

  1. Fran Griffin says:

    My last Bone Density test (May 2015) was slightly below normal. I was asked to stop my cod liver oil. Could you please tell me why???

    1. Bo Martinsen, MD says:

      Many years ago, there were some speculation that high vitamin A levels could lead to an increased risk of developing osteoporosis. At that time, cod liver oil was not purified and therefore contained lots of vitamin A.

      Recent research has shown that this link is unsubstantiated, and that cod liver oil may actually help preserve the bone structures, especially when combined with exercise. In addition, one tablespoon of Omega Cure only contains about 30% of the daily recommended value of vitamin A.

      I would discuss this topic further with your health care provider. If you would like me to send you more research articles connected to this topic, however, let me know.

  2. Holly Ryan says:

    Hi–
    I have read (if I understand the study correctly!) that it is “oxidized” fish oil fats which have an anti-inflammatory effect. The study said “omega-3 fatty acids, such as EPA, are highly poly-unsaturated and readily undergo auto-oxidation”. It sounds like cod liver oil, with its higher level of polyunsaturated fats that you talk about in the above article, would thus have the anti-inflammatory effect–have I got that right? I am not sure whether this particular anti-inflammatory effect would be applicable to my type-2 diabetes.
    Thanks for your thoughtful website articles!

    1. Bo Martinsen, MD says:

      I’m happy to hear you appreciate the articles, Holly.

      To answer your question, any omega-3 oil needs to be non-oxidized to deliver best results. This is because the omega-3 molecules are likely involved in protecting the cholesterol in the body from oxidation. To quote from another article I wrote, “By being in position to be oxidized first, the omega-3s let the cholesterol molecules remain in their pure, unadulterated state — thus preventing the buildup of plaque in the arteries. It’s important to note, however: If the omega-3 molecules are already oxidized and rancid, they are not be able to serve this function.”

      If you want to read more about the omega-3 molecules’ role in the cell and how they manage the body’s inflammation response, I’d recommend this article: “What Is Omega-3, and Why Is It Important for Your Health.”

      In terms of benefits for Type II diabetes, omega-3 is instrumental in lowering triglyceride levels. Studies from institutions like the University of Michigan reveal that having elevated triglyceride levels is one of the most important factors in predicting nerve fiber loss in diabetic patients.

  3. Mary Hedges says:

    I have been taking Omega Cure for several years but wonder if it is tested for Mercury and other pollutants?

    1. Omega3 Innovations says:

      Absolutely, Omega Cure is both purified and tested for mercury and other pollutants. We cover this topic more in-depth on the About Our Oil page in the “Excellent Purity Standards” section: https://www.omega3innovations.com/about-our-oil

      If you have more questions about this important subject, please don’t hesitate to let us know.

  4. Gary says:

    Does this product increase prostrate cancer developing? Thanks,

    1. Omega3 Innovations says:

      Hi Gary. Omega Cure should not increase the risk of developing prostate cancer. It is a GRAS product, meaning it is Generally Regarded as Safe by the FDA.

      We do understand your concern, however, given the much-publicized study from 2013 that suggested fish oil could be linked with an increased risk of developing prostate cancer. What you should know is that within the scientific community, that study was heavily criticized for its hastily drawn conclusions and poorly designed research protocol (The same study had, amongst other strange conclusions, also found that smokers had a lower risk of developing prostate cancer than non-smokers).

      If you’re interested in more information, we have written about omega-3 and prostate cancer in these two articles:

      Rancidity: The Link Between Fish Oil and Prostate Cancer?

      The Omega-3 and Prostate Cancer Resource Guide

      Also, you may be happy to know, a new research study from 2015 has shown that increasing one’s intake of omega-3 may in fact help inhibit the growth and spread of prostate cancer cells. Take a look here:

      http://www.nutraingredients.com/Research/Omega-3-may-help-fight-prostate-cancer

      We hope this helps answer your question. Let us know if you have others.

  5. Zona says:

    I am interested in the comparison of Flaxseed Oil to other oils? I have been using Barlean’s Flax Oil , organic pure and unfiltered, freshly cold pressed. It does not contain Vitamin A or D.

    1. Omega3 Innovations says:

      Hi Zona,

      That’s a good question. The reason we didn’t include flaxseed oil in this discussion is that it does not contain the same type of omega-3 you get in the marine-sourced oils discussed above. When you get your omega-3s from flaxseed or other plant sources like walnuts and chia seeds, it’s important to know that these plant sources only contain ALA omega-3, which has significant limitations.

      To quote from another one or our blogs, 12 Myths about Omega-3 Fish Oil:

      “In order for the ALA molecules to be effective in the fight against inflammation, they have to be elongated to EPA and DHA. This conversion step is more difficult and limited than most people realize. For example, you’d need to drink about a cup of flaxseed oil to get one teaspoon worth of EPA. This is why eating fatty fish or taking cod liver oil is more effective than flaxseed in putting a damper on inflammation and why the vast majority of omega-3 research has been conducted on fatty fish and fish oil.”

      You might also want to read another blog by Dr. Chalmers, which discusses how ALA compares to EPA, DHA and other types of omega-3 that you get in fish oils:

      https://www.omega3innovations.com/blog/epa-dha-ala-how-to-decipher-the-omega-3-alphabet-soup/

  6. Nelly Mastroeni says:

    Is it better to have Cod Fish Oil Carlston brand or Omega coming from anchovies and sardines? which of these two is better?
    Thanks for your reply,
    Nelly

    1. Omega3 Innovations says:

      Hello Nelly,

      Of course we recommend our Omega Cure cod liver oil to you as the best omega-3 supplement. Besides being exceptionally fresh, it is also a full-spectrum oil, meaning it has not been skimmed in the same way as most other cod liver oils and fish oils. You can read more about how Omega Cure compares here.

      To answer your question, however, we suggest you evaluate the best brand based on these two factors:

      1) Is the oil fresh? Taste and smell your chosen brands. Open up the capsules, if necessary. If the oil has a strong fishy smell or flavor, it is rancid.

      2) Am I able to get an effective daily dose? If you are going to get the benefits of omega-3, you need to take an effective daily dose, meaning for most adults between 2000 – 3000 mg of EPA/DHA omega-3 daily. Usually, a liquid supplement, as opposed to a capsule product, will make it easier to swallow that dose every day.

      Best of luck, and if you have more questions, don’t hesitate to let us know.

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