Fermented Cod Liver Oil — Should You Take It?

What is fermented cod liver oil and why is it different from regular cod liver oil? Why should you take cod liver oil, and specifically fermented cod liver oil?

Why Fermented Cod Liver Oil?

IMPORTANT UPDATE: I no longer recommend this product. Please see my post: My Take on the Fermented Cod Liver Oil Scandal

Dr. Oz was on Oprah a while back, saying that he believes cod liver oil is the number one nutritional supplement and that we should all be taking it. I heartily agree!

However, now there's something even better than cod liver oil: fermented cod liver oil.

We've been using the fermented cod liver oil from Green Patures for a month or two now and we love it. It's more economical, we like the taste, but most importantly, it is much more nutritious than any other cod liver oil on the market.

A lot of people ask what is the difference between regular cod liver oil and fermented cod liver oil.

Fermented Cod Liver Oil

Fermented Cod Liver Oil?

I recently heard Weston A. Price Foundation President Sally Fallon Morell speak about the differences between regular high-vitamin cod liver oil and fermented cod liver oil. She said that throughout history, cod liver oil was traditionally processed via fermentation, and not processed with heat. She said that the fishermen would throw the livers into a barrel, add a little sea water, and then leave it to ferment. Today, almost all cod liver oil is processed by heating it. Except for Green Pastures new fermented cod liver oil, which is made the traditional way. (Okay, maybe they don't actually use barrels and sea water but you get the idea.)

We know the benefits of raw foods and fermentation — so it seems obvious that fermented cod liver oil would be much more nutritious and more bioavailable to our bodies.

I was doing some reading on Dave Wetzel's blog (founder of Green Pastures) and he shares the following information about why fermented fish oils (cod liver oil and skate liver oil) are better for us:

1. Fermented fish liver oils are extracted without heat but rather a natural lacto-fermentation

2. We select exclusively organ tissue as the source of the fermented fish oils (compared to industrial model fish oils) as this is where the nutrients are located. There is much more to fish oil nutrients than EPA and DHA. It is only because of the heavy industrialization of this industry that this field of products has nothing else to discuss but Omega 3, EPA and DHA. These nutrients will occur naturally in all fish oils including the fermented clo/skate liver oil. I think the real story is in the thousands of micro nutrients that are provided in a Fermented fish oil.

3. Fermented liver oils are a deep rich pigment. Pigments are nutrients.

4. The oils have a 8-9mg/g total quinone count. Butter oil is in the 23-25 mg/g range. These figures are very high! The complex of the quinones is completely different between the fish liver oils and the butter oil. Even the quinone complex between the different fish oils is unique (variety is complete nutrition). Quinones consist of nutrients such as vitamin K's, vitamin E's, CoQ enzymes and other known and unknown nutrients/components.

5. Lacto-fermentation transforms natural vitamin A into different metabolites that are easily absorbed into our bodies (just as in your gut if your gut is working properly). I have found reference to at least 15 different natural forms of Vitamin A that nature provides. Not just the 2-3 that are commonly discussed.

6. There are over 3000 derivatives of vitamin D. Many are natural and others are produced in laboratories. Not much of the vitamin D topic is understood or discussed in mainstream science. Current discussions are just scratching the surface of the topic. Reminder, vitamin D is more accurately categorized as a hormone, not a vitamin.

7. At some point I would like to see the science on the effects of plant hormones and a variety of quinones as they relate to human health. Science is just starting to look at these questions.

8. Efficacy — there is a difference between the processed cod liver oil and the fermented CLO.

9. It takes 6 months to 1 year to make fermented cod liver oil. This is why it is no longer made.

10. Fish oils have historically been fermented for extraction; back in the Roman empire days, Viking era and all the way up to the Mid 1850's. Rendering was introduced during the mid 1850's as a more efficient fish liver processing method. The livers yielded a much higher total oil volume and the process could be accomplished in several hours rather than several months. What they did not understand is the effects that heat had on the nutrients (their science was not ready to address this question) . As with all industrial models, the focus was on: profitability, speed or turns and, marketability (taste).

11. Economical. Substantially more nutrients (including A/D) per ml or teaspoon compared to other brands. Source: Green Pastures

I don't know about you but I think this is very exciting. Thanks to Dave Wetzel for bringing back REAL cod liver oil made the traditional way.

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Ann Marie Michaels

I have 25 years of experience in digital and online media & marketing. I started my career in Silicon Valley and Los Angeles, working at some of the world’s top ad agencies. In 2007, after my first child was born, I started this little food blog which I grew to over 250K monthly unique website visitors and over 350K social media followers. For nearly 15 years, I've helped my audience of mostly moms and women 25-65 cook for their families and live a healthier lifestyle.

 The year after I started the blog, I founded a blog network in the health & wellness space called Village Green Network. I started the company on my coffee table and bootstrapped the business to over $1.3 million in annual revenue within 5 years. During that time, I helped a number of our bloggers become six figure earners. After being censored on almost every social media platform for telling the After being censored on almost every social media platform from Facebook and Instagram to Pinterest and Twitter, and being deplatformed on Google, I am now deployed as a digital soldier, writing almost exclusively about politics on my blog Cheeseslave.com. Because who can think about food when we are fighting the second revolutionary war and third world war? Don't worry, there will be more recipes one day. After the war is over.

64 thoughts on “Fermented Cod Liver Oil — Should You Take It?

  1. Thanks for posting this. A while back I bought some Nordic Naturals cod liver oil instead of the regular fish oil. I told my husband it was because of the vitamin D and vitamin A in the cod liver oil. He read the back of the bottle and was not convinced, as it shows extremely low levels. Is the packaging wrong, do you think, or should I expect extremely low levels?

    On another topic… (you are a wealth of information, btw)… I am currently on armour thyroid medication. I hate that I am on this and would like to naturally heal my thyroid. While armour is basically dessicated pig thyroid, I would like an option that doesn’t require a prescription. I was wondering if you could do a post on everything you are doing/taking to heal your adrenals and thyroid. I have a feeling my adrenals are bad as well due to some symptoms.

    I also wanted to say that I really appreciated you doing your post about the baby formula. We have been making it now for a couple of weeks and our baby seems to be doing well on it. If it’s not too personal to ask (since having babies we talk about this all the time :)) what were Kate’s bowel habits like after she started on the formula? Did she experience any constipation or green poos or were they still yellow? We haven’t had any problems, I was just wondering since you breastfed solely for 4 months and our boys only did for a week or so.

    Thanks for all of your information. Hope you are feeling better.

    Mrs. S

  2. Hi, Mrs. S,

    Can you tell me how much vitamin A and vitamin D the Nordic Naturals provides? How many IU per serving?

    Acc to the WAPF website, here are the correct amounts we should be taking:

    Children age 3 months to 12 years: A dose of cod liver oil that provides about 5000 IU vitamin A daily

    Children over 12 years and adults: A maintenance dose of cod liver oil that provides about 10,000 IU vitamin A daily

    Pregnant and nursing women: A dose of cod liver oil that provides about 20,000 IU vitamin A daily

    You do need the right ratio of A to D. It says on the WAPF site:

    “Some of the brands recommended in various articles on our website we no longer endorse because the manufacturer is removing vitamin A out of concerns of toxicity. An adequate dose of vitamin A-reduced cod liver oil may supply more unsaturated fatty acids than is considered safe. Some brands of cod liver oil contain very little vitamin D compared to vitamin A. The ration of A to D in cod liver oil should be 10 to 1 or less. (In one popular brand, the ratio of A to D is almost 100 to 1.) Vitamin A and vitamin D work synergistically and without the vitamin D, the vitamin A could be toxic.”


    Have you tried searching for “thyroid” and “adrenal” in the search box on my blog? I’ve written a lot about what I’ve been doing — and you can find all the posts by doing a search. The biggest thing I think that would help is Iodoral — that might help you start to reduce the Armour you are taking. Also helping to support the adrenals which will in turn support the thyroid.

    I also recommend reading Dr. Rind’s site — https://www.drrind.com

    Re: the formula — Kate didn’t really have any problems with constipation — and no green poos. She did however have cradle cap that would not go away when she was on commercial formula. When she got on the raw milk formula, it went away within a week or two.

  3. Hi Ann Marie,

    Would you happen to know how long fermented CLO can be stored before it loses potency? I have been searching the web, but cannot find any specifics on this.

    I just ordered from Green Pastures– Very excited! Thank you so much for this post.


  4. Hi there,

    I wish Green Pastures would make the fermented CLO with the butter oil! I buy their combo capsule right now and love it. I know that Weston Price found that combining these two fats worked wonders. I don’t always want to make butter oil so love the convenience of the combo.

    I think I’ll write Green Pastures and request it… not that I’ll get my wish, but it can’t hurt :)>.


  5. Ann Marie,
    This is a great post, just makes me feel good about taking my fermented CLO every morning.Cole takes it right off the spoon! What a guy! I am wondering if you know the difference between the high vitamin fermented CLO and the high nutrient fermented CLO? I orderd some at the Deidre Currie festival and I must have ordered the High Nutrient on accident.


  6. Book Recommendation:

    Salt, A World History

    By Mark Kurlansky

    I think this should be on every NT foodie bookshelf!!! He discusses the fermented fish throughout human history in detail and salt-making. Great, easy read.

    He also has another book, Cod, which is on my reading list.

    Ok, the librarian will sign off now before she gets too excited and recommends a dozen more!

  7. The Nordic Naturals that I buy is rather low in vitamin D – that is why I take extra D3 ( not ideally – but I REALLY need it living a dark place like Denmark)

  8. Excellent article! This is the first time I’ve read about fermented cod liver oil. Very interesting topic and something I would like to learn more about. It is true that omega 3 fatty acids, EPA and DHA are in the spotlight right now. Your comment on the dozens of other micronutrients found in fermented cod liver oils is well taken Thank you for an interesting article.

  9. I’m curious what kind of fermented cod liver oil you give your children….capsules, licorice flavored, cinnamon tingle? Do they drink it straight from a spoon? Just don’t want to waste my money.


  10. My daughter tolerates the cinnamon tingle. She is almost 2. When she was younger it was too “spicy” for her. So I’ve been giving her the plain no-flavor Quantum brand.

  11. I don’t understand what the fermented skate oil is that is mentioned above as being helpful with spider veins and how does it work? internally or topically? THANKS for any answers or help you have for me. I am plagued with spider veins all over my lily white legs!

  12. Hello. I was wondering if the Garden of Life brand cod liver oil was ok to use. They dont seem to process there oil like other brands and do not remove the natural vitamins.

  13. Can you tell me what you would recommend for getting children to take the cod liver oil. My husband loves it, my baby gets it in his homemade formula, and I can almost take it without gagging. I tried to give it to the kids in a shot glass with some homemade lemonade but they took a tiny sip (the oil had risen to the top) and both spit it out.

  14. Will the fermented clo help with my acne? I have developed some acne now that I’m an adult. Please anyone help! Thanks in advance.

  15. I put a little oil in a little grapefruit or pineapple juice in a baby food jar, shake it up well, and my daughter slurps it down with a straw. I think getting the oil past the lips helps a lot, and mixing with juice sort of emulsifies it and cuts the oily feel.

  16. @ Reshonda

    YES! I just got the new Wise Traditions journal (from https://westonaprice.org ) and there is an article in there about how acne is related to vitamin A deficiency. Start taking fermented cod liver oil!

  17. @ Greta & Cassie

    Yes, we buy organic fresh-squeezed orange juice just for the purpose of disguising cod liver oil. I also give my daughter the gummy fish. They look like “Swedish fish” and taste like cinnamon but they are pure cod liver oil (from Green Pastures).

  18. Interesting about vitamin A and the possible toxicity without D. Thank you for the thought starter on that. Will look into it, especially supplementing with D at high dose.

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  20. I couldn’t agree more with this post…Green Pastures has really hit the nail on the head when it comes to quality. We have seen time and time again people benefiting from their raw fermented cod liver oil. Too bad others are out there claiming to be the best…

    Thanks for all your information and may God bless your passionate pursuits for healthy living!

    If you have time, check out our site at www.threebrancheshealth.com.

  21. I wanted to respectfully say that I have followed much of what Weston A Price Foundation has recommended and that is why I tried the fermented cod liver oil from Green Pastures. But I have to say that I truely believe they are wrong on this one. I honestly think they have led people to believe that just because it is “raw” and “fermented” all buzz words to us, that it is better. I believe that FCLO was absolutely NOT meant to be food for us no matter what they say about the Roman soilders and Vikings. We have no quantitative way and truely knowing what all they ate. And all the studies that Weston A Price did was not with this gabage. Please do not follow blindly or throw out what your OWN mind and body are screaming at you just to believe what someone else says because frankly that is when a good thing can become a cult. I believe they are wrong on this and that people in this generation need to stick with what Weston A Price and what our own grandmothers have taken and taught us to take and that is regular cod liver oil. The fermented “sounds” better but use your brains and instints on this please and do not put this stuff into your body or the bodies of your precious children.

    1. i’m really glad you are going with your instincts and sharing your heart. one thing you did not mention was WHY you felt this is wrong. i’d be interested in any personal experiences you may have as to why you feel this way.

      without your putting down why you feel this way, there’s no way for us to know what it is you are truly objecting to.

      i have yet to try the FCLO, but i am very curious about it. i take carlsons brand of regular CLO right now.

    2. @Amanda

      The Green Pastures fermented cod liver oil is the only brand that is fermented the way it has been fermented for millennia. The other brands of cod liver oil are ALL heated and refined.

      You say you think the WAPF is wrong on this but you don’t say why. You also don’t present any sources re: why you think it is not a good food for us.

      Beliefs and opinion based on nothing are one thing; facts are something else. Present the facts, please.

      1. ‘The Green Pastures fermented cod liver oil is the only brand that is fermented the way it has been fermented for millennia.’

        Sorry but where is the historical research into ‘fermented cod liver oil’ being used for ‘millennia’-and specifically by ‘whom’. And was it intentionally fermented and recorded as a recipe or did archeologists find traces of decomposed oil in containers?You say Romans, Norseman etc but this seems at this stage,annecdotal. The trouble with these sort of health fashions is that they can carry the romance of traditionally wise grandmothers etc.. But unless one can provide historical
        fact it can just be myth- which is a dangerous game to play with your health.

        I personally have no issue with traditional foods having grown up on them -nor with cod liver oil-but there are big claims being made about these products and i have yet to find any historical records on fermented cod liver oil-[besides Weston A prices ‘research’]

        I think just because one is hopeful it is no reason not to investigate thoroughly before flinging oneself onto a bandwagon.

    3. Hey Amanda and Ma,
      I think you should look into Dave Wetzel’s method of fermenting the CLO and how he came about it.

      @ Amanda: I’d be curious why you consider FCLO wrong or why you are so strongly against FCLO.

      1. Hi Rob

        Thanks, but can you provide a link please?

        I just want to be clear that I’m not necessarily against it-

        BUT I am experienced enough to have seen
        many many trends and fads come and go in the health food sector-people become absolutely passionate about whatever the buzz is-often disproportionately- and during that phase of ‘infatuation’ if you will – like falling in love with a new religion, belief system/person or substance-that will make everything better, they do not want to hear a word against there chosen product, not even if its the voice of reason suggesting some proper healthily sceptical research should be done or searched for.

        And then suddenly the ‘substance’ whatever it is -is barely heard of again -and becomes ‘So last season’ but often not before people cause themselves problems-you must have seen this social phenomenon yourself.

        I really feel Cheeseslave should be a bit more rigorous about this,and err on the side of caution. Some of the ‘advice’ is problematical and potentially dangerous.

  22. ok, ok… I’ll go take it right now. lol…. I’ve been a little spotty about taking mine lately. I do feel GREAT when I’m good about it though!

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  24. Hello, I have been researching FCLO and CLO for some time and hoping for more information. I see all of the WP folks love Green Pastures and FCLO, but I don’t see tons of research on the GP site. I respect the good work they do, but also feel that I need to be knowledgeable and not just accept something b/c others are saying it is good and “sacred”. I am really eager to use FCLO from GP, but just need some clarifications. As much as I don’t like federal bureaucracy watching over and meddling with what we do, in some ways I like the standards being set so that we can make sure things like toxins are not present in our supplements. The common person may not have the time, intelligence, or resources to research well and be as thorough as they may want to be. It is even confusing for me and I prioritize these things. All this being said, I have written to GP to help me with some questions. I am posting the letter here in case anyone else can also help me and share info. Thanks a million in advance!!!
    Jessica (see questions below and sorry for such a long post 🙂


    I am new to FCLO and have been researching it earnestly. I do not see some of my questions in your FAQ. Please forgive me if I overlooked them.

    First, I saw under your “Environmental and Sustainability Statement” that you say in the third paragraph- “All our fish products utilize fresh raw materials that are by-products.” I do not understand what this means. Is the oil made from by-products or the organ itself?

    Second, I see that the Peroxide Value noted is 10. I read that the Council for Responsible Nutrition’s Voluntary Standards for Omega 3’s list the Peroxide Value as a MAX of 5 mEq/kg. 10 is double this. I am wondering also what the Anisidine values are and the TOTOX values.

    Also, I know the fish is fermented, but I thought that some level of molecular distillation is needed in order to remove toxins and contaminants. Is this true? I know it is necessary to meet California’s Prop. 65. I see you have N/A here and I am assuming you don’t meet it b/c you are not marketed as a supplement.

    So, how is the fish cleansed of contaminants, kept fresh from boat to your facilities (I know some brands like Nordic Naturals use Nitrogen) and where are you facilities?

    Please do not think I don’t see the value in this sacred and time consuming practice of fermentation. I am seeking clarification and a deeper understanding.

    Thank you so much for your time,
    Jessica Parthasarathy

  25. @Jessica Parthasarathy

    I think you are being really sensible-This is just the approach that is needed-I hope you get the answers were I didn’t and will post them here for those of us who take a more rigorous approach to supplements- my reservations with FLCO are growing as a result of vague info on blogs like these.

    I have to say Im very alarmed by the gung ho attitude on this blog to what is potentially a dangerous substance,and that is also being ‘prescribed’ by Cheeseslave[with what credentials I wonder??] for an 8month baby, which is truly disturbing!

    Cheese slave says this to another poster’ You say you think the WAPF is wrong on this but you don’t say why. You also don’t present any sources re: why you think it is not a good food for us.

    Beliefs and opinion based on nothing are one thing; facts are something else. Present the facts, please.’

    BUT WHERE is the research either into the oft repeated statement that it ‘was used by Vikings and Romans’ [The inference being that shrouded in the mists of antiquity is this supplement valued for millenia and recently rediscovered} or into the specific benefits of fclo over unfermented and its safety, that is not Weston A price.

    Its a double standard to ask posters to be specific and accurate about research when the blogger doesnt provide it herself and evades extremely valid points and questions-

    1. Ann Marie, Please help!! Also, I forgot to ask how the Cod Livers are kept fresh from the Arctic to Nebraska (where I believe they are fermented). Thanks again!

        1. I would love to get some feedback on this too. Interesting topic. Also, there is radiation debris from Japan’s catastrophe showing up all over the world (even in Massachusetts) so how can we be sure that any fish oils are safe? I don’t see this data on GP page at all and very little on their test results from toxicity and oxidation measure (under their purity statement). I think someone was saying that GP FCLO is made in Nebraska from cod livers that are gathered in the Arctic. So, how are they transferred and stored to prevent oxidation and how are they tested for toxicity? Cheeseslave can you help us out? Thanks!

  26. I also wanted to add my concerns about heavy metals in the Green Pastures fermented cod liver oil. Though heating is clearly going to kill off most of the nutrients we need, what other process do they use to ensure that the cod liver oils have mercury and other metals removed. Just because it’s ‘wild’ and it comes from the Arctic does not meet it’s metal-free. That’s a very dangerous assumption. The information on their site is too vague for my comfort — having dealt with significant heavy metal toxicity in the past. I would also worry about giving this to children without more rigorous studies. They say each batch is screened — then each batch should be numbered and the public allowed to call and verify what is actually in it. I think fermented fish is a strong part of a healthy diet — but taking concentrated fish oil daily could significantly add to someone’s heavy metal load if it’s not truly contaminant free.

  27. Maybe this article written by the owner of Green Pastures will help answer some questions of FCLO…not sure why I didn’t find this on the Green Pastures website, but I found it helpful.


  28. I do not wish to take GMO organisms into my bloodstream

    Please label all foods that contain them clearly



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  30. I can’t say the Censor’s warning makes commenting terribly inviting.

    That said I can’t find anything about WHAT is fermented? Fermentation requires carbohydrate and fish doesn’t seem to be a carb source.

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  33. Interesting discussion! I am looking into taking FCLO and wanted to ask what is the recommended dosing? Any concrete answers on the heavy metal testing? I am struggling with acne and I also heard that it helps with keratinosis pilaris? I was looking at the butter oil/FCLO capsules from GP. Thanks for the info!

  34. At first I thought you were acting crazy on the whole fermented cod liver thing. Well, I was taking the oil along with my children up until a few days ago. Myself and my youngest son always had a stomach ache and I couldn’t get it to go away. No matter what we took our stomachs always ached. I spent many nights up with my youngest son due to his stomach pains. I myself would feel lethargic at night and when I woke up. We stopped taking the oil and started Carlson’s cod liver oil and what a huge difference. We no longer have stomach issues at all. My energy is back to normal. We eat a very healthy diet and I did not want to believe this oil could cause these horrible stomach pains but when we stopped the fermented oil the stomach issues stopped. Also, me teeth no longer hurt.

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