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cod liver oil

Cod Liver Oil – 3 Reasons to Avoid It And the rise of Fermented Cod Liver Oil (FCLO)

written by Vin Kutty

comments 43 comments

cod liver oil

In early 2010, an environmental group sued several fish oil manufacturers for selling polluted fish oil.

All the major TV news channels covered the stink. Every single channel re-worded the plaintiff’s press release without digging deeper. The late Paul Harvey would have dug deeper for ‘The rest of the story.

The products named in the fish oil lawsuit are:

  1. GNC Liquid Norwegian Cod Liver Oil
  2. Nature Made Cod Liver Oil
  3. Nature Made Odorless Fish Oil
  4. Now Foods Double Strength Cod Liver Oil
  5. Now Foods Salmon Oil
  6. Now Foods Shark Liver Oil
  7. Solgar 100% Pure Norwegian Shark Liver Oil Complex
  8. Solgar Norwegian Cod Liver Oil
  9. Twinlab Emulsified Norwegian Cod Liver Oil
  10. Twinlab Norwegian Cod Liver Oil

Notice a pattern?

6 of the 10 products named in the lawsuit are Cod Liver Oils.
cod liver oil
8 out of 10 are ‘liver’ oils.

None of the TV channels that talked about this endlessly pointed this out!

The other four were Shark liver oil or Salmon oil.

This cod liver oil issue was not a coincidence or a surprise to those of us in the fish oil industry.

Here’s why:

  • Cod, like Shark, are long-lived fish. As they go about living for years and years, and during that time, they accumulate environmental toxins.
  • And the toxins are most concentrated in the livers.

So when you drink Cod liver oil, you should expect environmental toxins! That just makes sense!

This extensive report from Norway is revealing.

So that’s Reason #1 for Avoiding Cod Liver Oil: Pollution

Reason # 2: Lack of Industry Participation & Transparency

They say you can tell someone’s character by the company they keep. You can apply that to professional company as well.
cod liver oil

Reliable fish oil manufacturers are members of GOED, the Global Organization for EPA and DHA Omega-3.
It is an industry group that sets standards and requires that members follow a certain code of conduct and produce products that meet quality standards. Sounds fair to me.

Oddly, Cod liver oil companies, even though they sell 7% of all Omega-3 pills, have been absent from GOED. Lots of fish oil, krill oil and algae oil companies openly belong to GOED. But you’d be hard pressed to see Cod folks. Hmm.

Part of the reason is that it is a very traditional industry that’s out of the mainstream. GOED has been reaching out to Cod liver oil manufacturers to help them embrace quality standards. We’ll see if they are successful.

Reason #3: Over-fishing.

Atlantic Cod is an over-fished and threatened species.
Cod population has declined drastically
ICES (International Council for the Exploration of the Sea) coordinates the management of North Atlantic fisheries. We get most of our Cod liver oils from the North Atlantic.

There are a dozen countries that harvest cod and this makes it very hard to manage. Only 1 out of the 12 areas has sustainably managed their cod fishery – Norway. All the others have over-fished to the point of not having enough mature fish to reproduce the stock back to normal.

Of course, if I have to choose between my health and the environment, I have to side with my health. Sorry!

But you don’t have to make such dramatic choices. Cod is not the only source of Omega-3 available to you!

I know many people who take cod liver oil because it contains these Vitamins A and D. Both are critical, but there are purer sources.

If you want Vitamin A, you can take a purified Vitamin A extract from cod liver oil – get the goodies minus the contaminants. And if you want Vitamin D, cod liver oil doesn’t give you enough of it anyway…unless you take it by the spoonfuls. You’ll still need a separate Vitamin D supplement. You need about 4000 IU per day and cod liver has less than 10% of it.

Fermented Cod Liver Oil

And there is this thing called fermented cod liver oil or FCLO.

It’s an old scandinavian treat and popular with folks following the ‘paleo’ or caveman diet. I fully agree with the principles and science behind the paleo diet, but I don’t get the fermented cod liver oil thing.

The manufacturing of modern FCLO product is more shrouded than a health product ought to be. Technically you cannot ferment oils and fats, so it should be called ‘Putrefied liver oil.’

Traditional cod liver ‘fermenting’ technique:

  • Throw raw cod livers in a vat with some brine
  • Leave it exposed to air and sunlight for, oh, about 6 months
  • Wait for the rotting livers to release the oil. It rises to the top and you skim it off.

Yes, it contains nutrients like Vitamins A and D that most people are deficient in. And in the right ratios, no less. There may even be some Vitamin K2 in there. But I’d much rather you get that from your diet. I try to get my A, D3 and K2 from liver, grass-fed butter, sunshine, cheese, and eggs – all foods on the Paleo altar. I also supplement with A, D3, K2 and E complex when my diet falls short.

Besides, fermented fish liver is simply too repulsive a concept for me to choke down. (Not that I’m squeamish – I faced my fears and choked down some super stinky fermented herring called Surströmming while visiting Stockholm. Hey, when in Rome…)

We live in a post-industrial world. There are literally over a hundred types of PCBs in fish liver. Modern fish oils go through several purification steps that virtually eliminate environmental toxins.

FCLO  passes the 90 parts per billion industry threshold level. That’s a low bar and doesn’t make me comfortable. I want it under 5 parts per billion. Until then, no thanks.

Is My Cod Liver Oil bashing Fair?

OK – you may be thinking that my Cod-bashing ways are self-serving. After all, our company sells concentrated fish oil. I’m not trying to pump up sales of our product by bashing cod liver oil (we can barely keep up with demand!)

I expect to get a lot of hate mail for this one. So, to my naysayers, I say:

  1. Show me proof (an IFOS report or the like) that your cod liver oil is pure, clean and potent and that it passes standards that fish oil manufacturers follow
  2. Show me how it’s made and processed
  3. Show me how much Vitamin A is present in your product
  4. Show me some membership or association with some group whose rules you have to live by
  5. Show me that the cod are harvested sustainably

Most GOED members can easily do this.

If your cod liver oil can do all of the above, I will happily eat a heaping plate of crow (or fermented cod livers.) Your pick. I’m frequently wrong (just ask my wife) but I don’t think I’m wrong about this.

A couple of centuries ago, cod liver oil was enough to cure kids with rickets and other ailments.

Cod liver oil was your great granddaddy’s fish oil. Let it stay that way.



Join the conversation

    • Leslie, you obviously didn’t get his point. There is nothing wrong with cod liver oil itself. What is wrong is the way it is harvested, and manufactured, or brought to public consumption. Instead of cod liver oil, why not eat sardines? They too have all the omega fats of cod liver oil. For all the cod liver oil you consume, your skin is very thin, and your brain can’t seem to process contrary information as a being a good thing. Why should anyone listen to you or me if you tell him to be quiet? Eh what’s the use? Slurp down your expensive cod liver oil. I’ll save money by eating cheaper sardines, and save cod from being over fished.

      • Cod liver oil is not expensive. In fact, it is likely cheaper than sardines. A 12 fl oz. bottle of Cod liver oil costs me $10 and lasts me nearly 2 months. 2 tins of sardines a day at even $1 each would be $120. What’s the more economical and beneficial route? The cod liver oil.

        • Hi Mike W – fish/cod liver oil is certainly the cheapest way to get the most Omega-3. But sardines are PACKED with a lot of other nutrients that you need. And each sardine you eat is (hopefully) taking the place of a slice of bread or cookie! The way I look at fish oil is that it is NOT a replacement for eating fish, but a way to get much needed Omega-3 if I happen to skip eating fish on a regular basis.

  1. Leslie I agree with you he needs to STOP with the bull shhhhht. i’ve took cod liver oil for decades and i give it to my children and nothing has happen to us we are all still alive living on our borrowed time!!!

    be blessed

    • Leslie & Cubanflowers – If you are happy with your cod liver oil, by all means, continue taking it. My point is that there are better alternatives these days, like molecularly distilled fish oils, which have a lot less environmental toxins than cod liver oil. Large, long-lived fish like Atlantic Cod and Salmon naturally tend to accumulate toxins over time. The level of toxins are probably low enough to not cause serious harm, but then there is the issue of Atlantic cod being over-fished. It just doesn’t make sense to me if there are better alternatives. Although, I’m beginning to change my opinion on the ‘too much Vitamin A’ thing…I’m finding out that a lot of people are actually deficient in Vitamin A and could probably use a couple of ounces of liver, like our grandparents used to eat.

    • Cubanflowers: Your post made me smile…not at the grammar (Leslie included) but that you first swear at Vin to “stop with the bull shhhht” but then you say “be blessed.” Maybe it’s just tough love? 🙂

  2. Actually, cod liver oil makes use of the livers instead of discarding them, as is customary with many other species of fish. Molecularly distilled cod liver oil, a refined food, is likely not beneficial or harmful. Fermented cod liver oil, a whole food, has a long history.

    • Hi Greg – molecularly distilled cod liver oil has little or no Vitamins A and D. Sometimes, these are added back…from non-fish sources – I’m not a fan of this practice, even though it is not common. There is still Omega-3 in molecular distilled cod liver oil, so there is some benefit.

      Fans of fermented cod liver oil like the facts that it is a whole food, contains natural ratios of preformed Vitamin A (Vit A deficiency is becoming increasingly common) and D. In northern Europe where this practice was common, it was often the only potent source of these fat-soluble vitamins. Scandinavia doesn’t see much sun for half the year. Lately, followers of paleo diets (I’m one of them) have begun taking fermented cod liver oil. I prefer to get my Omega-3, A and D from fish/fish oil, liver, eggs, animal fats and sunshine respectively.

      – Vin Kutty

  3. Haha..this is funny..but very good points..thanks. Glad I decided to read this before I purchased it.

  4. I have no problem with “pharmaceutical grade fish oil” but when it comes to cleaning it so much you remove all natural nutrient from it, and then “fortify” it with synthetic versions of vitamin a or d you are adding to the cancer rates, and making people ill, because the synthetic versions of those are toxic.

    PS: livers are to clear toxins out… does not mean they are full of toxins if they’re functioning well at their job. But they are more concentrated in the nutrients they store, such as iron and vitamin d etc naturally.

    fermentation processes do not involve cooking or filtering all the nutrients out of something. nuff said.

    • Hi Valerie – you say you don’t have a problem with modern fish oil, yet you seem fairly convinced that we are adding Vitamins A and D to our products and that is giving people cancer. I don’t intend to convince you otherwise.

      Cod liver oils have gained in popularity due to it being an ancient food and appearing more natural, with Vit A and D. All true. When the Vikings ate cod liver oil centuries ago, they didnt have to deal with the polluted environment we do now. I’ve tested enough cod liver oil in my career to know that they are consistently higher in environmental pollutants than regular fish oil. Fermentation process does not clean this up. I pass. The reason we purify and concentrate our oil to high levls is to get rid of any smidgen of environmental toxins present and to concentrate the Omega-3 present.

      I’ve said it before on this website several times and I’ll say it again – if you want Omega-3s, eat more fish. If you want Vitamin A, eat more animal fats and liver from grass-fed ruminants. If you want Vitamin D, get it from the sun – Vitamin D from pills only help with calcium transport – they are not the sulfate form. You need the sulfate form for several health benefits.

      ALWAYS go with the real food – supplements are for people who are unable, unwilling or just cant stand the real thing.

      • You imply that sun exposure is necessary for the “sulfate form” of vitamin D and that only the “sulfate form: imparts certain health benefits. Can you tell me your source of this information. Thanks.

        • Hi Steve – I need to state a couple of things upfront: 1) sun exposure, especially if excessive, is not without risk and 2) the studies that favor sun light over Vitamin D supplements are not numerous. Some are compelling, but the evidence still feels less than rock solid.

          Here are a couple of studies:
          Sunlight Has Cardiovascular Benefits Independently of Vitamin D
          Does Incident Solar Ultraviolet Radiation Lower Blood Pressure?

          I’ve read a couple of more such studies. The number of studies that clearly show advantages of sunlight over vitamin D3 supplements is small. But most seem to show cardiometabolic benefits. This could be because of the production of nitric oxide in the skin, which helps with vasodialation. The sulfate angle you mention may have to do with ease of transport within the body – ability to be transported by blood (preferred?) rather than via lipoproteins.

          Having said all that, I had a conversation with a dermatologist friend just yesterday about this. She is trying to convince me to quit baking myself in the midday sun just to get these benefits that D3 supplements cannot provide. She may win the argument. Still, I put on my shorts, cover my face and arms…and put a towel out on the lawn and bake myself for about 5 minutes on each side. I might do this every other week or so from late spring to early summer. By the end of summer, I am sick of the sun and heat and don’t want to be in it.

          I look at sun exposure from an ancestral perspective – we probably got a lot more of it in centuries and millennia past. That’s what our bodies are built for. We probably consumed a lot more natural sun-protective compounds like lutein, zeaxanthin, and especially meso-zeaxanthin during pre-agricultural times than we do now. It may be somewhat risky to get an ancestral amount of sun without also consuming an ancestral amount of carotenoids and other sun-protective nutrients like the ones mentioned above.

          PS: there is a microbiome angle to sunlight as well:

            • Hi Precious – I’ve seen nothing that indicates that the problem has worsened or improved. I still find no reason why someone should take cod liver oil when you have access to seafood, organ meats from well-fed mammals, sunshine, and highly purified and modern Omega-3 oils.

              Cod liver oils have trace amounts of Vitamins A and D. You can get that elsewhere.

  5. hi Vin Kutty
    please read your comments below, they are contradictory.
    “Cod, like Shark, are long-lived fish. As they go about living for years and years, and during that time, they accumulate environmental toxins.
    And the toxins are most concentrated in the livers.”

    Vin Kutty February 17, 2013 at 10:33 pm
    Hi AE – agreed. Liver is a processing center, not a storage unit.

    • Hi Mac – I should revise that. As is, it is contradictory. The truth is, liver is largely a processing center and not a long-term storage unit. But at any given time, liver still tends to house a lot of both the good and the bad. Products marketed as ‘cod liver oil’ are consistently the most polluted Omega-3 oils around. This may have less to do with liver as much as it does with Atlantic Cod, the species used to make these products. My stance on cod liver oil remains the same.

  6. I’m interested in finding a source for shark liver oil, however, I do NOT want anything to do with any products from the Pacific Ocean (RADIATION). So I’m thinking Atlantic Ocean sources for the shark liver oil is a much safer option.

    • Hi Terri – I would strongly caution you against consuming shark liver oil or shark products of any kind. They are long-lived apex predators, which means it accumulates a whole bunch of environmental toxins. Radiation from the pacific would be the least of your concerns if you end up taking shark liver oil.

      Just curious – is there a reason why you are looking for this product?

  7. Thank you for your commentary Vin. I have been taking Cod Liver Oil for a few years. I worry about the overfishing of cod though so I have decided to stop taking the oil. Sustainable cod fishing is a myth.

    Your comment about cod being long lived creatures and therefore major accumulators of toxic materials might have been true a hundred years ago. Due to decades of overfishing, cod don’t live very long now. The big ones are long gone and the cod in these times are lucky to live long enough to spawn once and are quite small when they are trapped in the net of a cod trawler.

    Consuming cod, in any form, is unethical in my opinion and I will no longer do so.

    • Hi Ronk – you may be right that there is no such thing as sustainable cod fishery. If you can overlook the environmental impact and potential issues with toxins, the only reason to consume cod liver oil is that it has pre-formed Vitamin A, a nutrient lacking in our diet because we no longer eat liver and organ meats from cattle like we used to.

  8. When I was young I used toSharkoferrol with milk in my breakfast. Now I
    am taking shark liver regularly. Believe it or not, shark liver oil is the best
    supplement you can take. Regards.

    • Hi Suresh – shark liver oil is a phenomenally bad idea. Sharks are long-lived apex predators. This gives them plenty of time and opportunity to accumulate environmental toxins like PCBs, Dioxins, arsenic and mercury. I would much, much rather you get a high quality cod liver oil.

  9. So….where do I get some of this “Scott’s Emulsion?” I am always looking for ways to reduce my repugnance, if not for fish oils, just in general. 🙂

    Great article, Vin. Very educational, as usual.

    • Hi Hunter – I don’t know. Some of their labels say they have added Vit A, others don’t. Better to call them. However, they have a nice 10:1 ratio of A to D.

  10. Have you seen the latest news on fermented cod liver oil? I guess you won’t have to eat a heaping plate of crow.

    Fermented cod liver oil is sold as a “superfood,” or even as the “Rolls-Royce” of cod liver oils, which are a source of vitamins and omega-3 fatty acids.

    However, this report says that Green Pasture’s (GP) “fermented cod liver oil,” or FCLO, is rancid, putrid, low in fat-soluble vitamins, and is not even made from cod. Who says so? Kaayla T. Daniel, Ph.D., who serves on the WAPF board of directors, where she is both vice president and a past recipient of the organization’s Integrity in Science award. Daniel is certified as a clinical nutritionist by the International and American Association of Clinical Nutritionists.

    • Hi Mo – yes, I’ve read the report published by Dr. Daniel. There was never any risk of me having to ‘eat a heaping plate of crow.’ 🙂

      She contacted me a few months before it was published to get my take on the matter. Unfortunately, I was out of the country at the time and never got a chance to share my data with her. The information I had does not contradict allegations made in the report. However, my focus was/is on rancidity and environmental contamination. Dr. Daniel also focuses on other issues in her report: that FCLO is made from Pollock and not real old world Cod as advertised (this is not a safety issue but a labeling issue), that there may be adulteration with rancid vegetable oil (I don’t think the evidence is compelling enough to support this allegation, but warrants further investigation), and that FCLO does not contain adequate Vitamins K2, A, and D to warrant all the excitement – (I agree but I have no data to support this.)

      I know Dr. Daniel well enough to know that her credentials and intent are solid. Her future role at the Weston Price Foundation is probably less so because WAPF is digging in. WAPF and the ancestral health thought leaders all unquestioningly drank the FCLO koolaid without critically analyzing the product claims. I think their hearts were in the right place – ‘take old-fashioned cod liver oil because it contains fat-soluble vitamins so rare in our diets.’ What’s not to like about that notion? On paper, I agree too.

      But after I bought the product several years ago, I knew instantly we had a problem – of rancidity. Back then, it was probably still made from Cod and that fish species is typically high in environmental contaminants. You can get the contaminants out if you use multiple molecular distillations and modern purification techniques…but that would also remove all the Vitamins A, K2 and D. I knew there was a problem 5-6 years ago. But that message coming from me would have seemed highly self-serving, no matter how well-substantiated my scientific arguments were.

      I think Dr. Daniel would have achieved more with her report had she removed the biting tone and emotionally charged language from her report. At least the issue has been brought to the surface by someone who has no conflict of interest. It’s about time.

      • The issue of rancidity (oxidation) stretches across all fish oils!
        This has been shown time and time again with fish oils i.e. whether directly derived from fish or synthetically recreated.
        Almost all fish are over-produced whether from the ocean or open aquaculture farms!
        The only fish I consume is whole fish from closed aquaculture farms!

    • Hi Mick – this is an observational study, so you cannot draw cause and effect conclusions.

      We know that fish intake is correlated to decreased risk for asthma. No surprises there…but cod liver oil intake has a U-shaped benefit profile regarding its effect on asthma – too little and too high are associated with higher asthma.

      We may assume that the U-shaped curve suggests that too little cod liver means there is higher inflammation. We may also assume (right or wrong) that too much may cause oxidative burden on the body. It may also have to do with higher levels of environmental toxins in the cod liver oil.

      People tend to instinctively point their finger at Vitamin A…I have a big issue with that because Vitamin A, especially in the presence of Vitamins D, K2, and some E does not cause problems at typically suggested doses of cod liver oil. It is virtually unheard of having issues with Vitamin A if you are taking between 5,000 and 10,000 IU of Vit A per day especially in the presence of other fat soluble vitamins. Despite the slightly misleading language in the abstract of the study you linked to, this study DOES NOT suggest that Vitamin is the issue.

      My preexisting biases against cod liver oil remain – they are more likely to contain higher environmental toxins and higher TOTOX readings. That’s where I’d look instead of Vitamin A.

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