Important Update on Cod Liver Oil
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Important Update on Cod Liver Oil


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An independent analysis of Green Pastures Fermented Cod Liver Oil suggests that it may not live up to its claims. But is the analysis sound? Get the nitty gritty details and my recommendations.

best cod liver oil
One of the best ways to get a daily dosage of cod liver oil is in capsule form. obewon/iStock/Thinkstock

As many of you know, I’ve long been an advocate of cod liver oil. In addition to being a good source of long-chain omega-3 fats like EPA and DHA, it’s rich in vitamins A and D, which are difficult to obtain elsewhere in the diet.

For several years I’ve recommended Fermented Cod Liver Oil (FCLO) from Green Pasture. I took this product myself, and my wife took it throughout her pregnancy and while she nursed our daughter, Sylvie. I recommended it to my patients, readers, podcast listeners, and friends and family.

About a year ago, I received an email from a new company called Rosita Real Foods regarding a new cod liver oil product (called Extra Virgin Cod Liver Oil, or EVCLO) that they were bringing to market. Leading up to the launch of their product, they sent out a series of emails explaining how it is manufactured, processed, tested, and produced.

I was impressed by their transparency: they provided test results for fatty acids, vitamins, dioxins & PCBs, rancidity, and oxidation by-products on their website, along with a list of institutions that performed the testing as well as the dates of the tests.

As soon as the EVCLO product became available, I ordered some. I noticed right away that it smelled, looked, and tasted fresh. This, together with Rosita’s transparency and third-party testing, was enough to convince me to switch over to EVCLO and begin recommending it to my tribe.

Independent Analysis of Green Pasture Fermented Cod Liver Oil

Last weekend I received an email from Kaayla Daniel, a nutritionist who has been involved with the Weston A. Price Foundation (WAPF) for many years. She had grown increasingly suspicious of the Green Pasture product recently, and she requested that the WAPF conduct independent analysis of it to determine whether it lived up to its claims. The WAPF voted not to conduct this testing, so Kaayla took matters into her own hands.

My take on the recent report on Green Pastures Fermented Cod Liver Oil.

The result is a 110-page report with test data from multiple independent laboratories both in the United States and abroad with expertise in testing marine oils and nutrient levels. You can read the full report for free here. But in short, these were the conclusions from her report:

  • One of the three batches of FCLO that were tested was found to be rancid, based on free fatty acid values.
  • Levels of vitamins D, A, and K are lower than Green Pasture claims on its website.
  • DNA testing of the livers purportedly used to make FCLO suggests that it is not made from cod, but from Alaskan pollock. Oils from Alaskan pollock liver have a different nutritional and fatty acid profile than those from cod livers (which explains the next finding).
  • While all other cod liver oil products contain more DHA than EPA, FCLO contains more EPA than DHA. This EPA-to-DHA ratio is consistent with what you would find in Alaskan pollock liver oil.

Kaayla’s report certainly raises a number of issues that deserve attention. However, I do have some concerns about the data she presents. They arose out of research I did over the weekend, as well as discussions with colleagues in the fields of biochemistry, nutritional science, and lipid science.

Are the Fat-Soluble Vitamin Tests Results Reliable?

Testing for fat-soluble vitamin levels is incredibly complex and not yet standardized. I am concerned that the approach to quantifying them in Kaayla’s report was oversimplified. This is based on communications I’ve had with Dr. Chris Masterjohn, a nutritional scientist and an expert in fat-soluble vitamins.

Chris has noted that there are likely at least half a dozen (if not more) vitamin D compounds in cod liver oil, and it may be that the preponderance of biological activity comes from compounds other than vitamin D3 or D2. (This is the case with cow’s milk, where most of the vitamin D activity comes from 25(OH)D and very little comes from vitamin D.)

In fact, one vitamin D expert has remarked that a scientist could spend an entire career simply characterizing the factors responsible for the vitamin D activity in cod liver oil. Clearly there’s a lot more to this than comes across in Kaayla’s report.

This may explain why Dave Wetzel, the owner of Green Pasture, has been attempting to quantify the fat-soluble vitamin content of FCLO for many years but has never been entirely successful. It seems that there are many different vitamin-D-like or vitamin-K-like compounds in FCLO (and other cod liver oils) that cannot be easily measured with current analytical methods. Measuring the biological activity of vitamin D compounds by feeding the substance in question to rats may be a better method of determining vitamin D content than quantifying the levels of D2 and D3. (Green Pasture did this kind of testing in 2009, and the results indicated that FCLO contained roughly 400 IU of vitamin D per tsp, which is in line with what you would expect for cod liver oil.)

Is FCLO Really Rancid?

If FCLO were truly rancid, we would expect to see very low levels of EPA and DHA in the oil. Once fatty acids (like EPA and DHA) undergo peroxidation, they cannot be regenerated from their peroxides. However, on page 102 of Kaayla’s report, the lab results show that FCLO has approximately 315 mg/tsp of DHA and 685 mg/tsp of EPA, for a total EPA/DHA content of 1,000 mg. According to Rosita’s website, EVCLO has approximately 1,200 mg of EPA/DHA combined. So, while the batch of FCLO tested in Kaayla’s report contained less EPA/DHA than EVCLO, it still contained a substantial amount—which would not be expected if the oil were rancid as claimed.

The claim that FCLO is rancid was based on high levels of free fatty acids found in the oil. Kaayla suggests that this is an accurate way to determine rancidity in marine oils. However, according to most lipid scientists, hydrolysis of triglycerides and other esterified lipids into free fatty acids is completely unrelated to oxidation and is therefore not an accurate measure of rancidity.

Instead, TOTOX, anisidine, MDA, and TBA/TBARS are better indicators of whether an oil is rancid. In Kaayla’s report, FCLO received good scores from all of the labs on TOTOX, and all but one lab (which was not able to obtain a result at all) on anisidine. Two of the labs reported normal TBA values. One lab reported a TBARS value that was high, and another reported an MDA value that was 10 times higher in FCLO than in other cod liver oils.

These results are somewhat mixed. The majority suggest that FCLO is not rancid, while two of the test results suggest that it is. I think more investigation is needed on this before any firm conclusions are drawn.

Variability in Test Results from Lab to Lab

There was significant variability in test results from lab to lab and test to test. The samples Kaayla sent in for testing had manufacture dates ranging from 2012 to 2014. It’s conceivable that Green Pasture changed its production methods during that period of time, which could explain the variation in the results.

Another possibility—and one that is likely—is that the variability is at least in part explained by different methodologies and techniques used by different labs. Unfortunately, this is difficult to verify and investigate further because Kaayla was not able to name the labs in her report (due to legal agreements).

Though this seems to be common practice in this field, I feel that the omission of the names of the labs that performed the analysis weakens the reliability of the findings. Given the known complexities involved in this kind of testing, as well as the variability between labs, it’s unfortunate that we can’t ascertain which lab did which tests. This isn’t a criticism of Kaayla, because I imagine it was beyond her control, but I do see it as a downside.

Summary and Recommendations

Kaayla’s report does raise some concerns, but clearly there is a lot more to it than initially meets the eye. Rather than viewing her report as the final word, I hope that it’s the spark for an informed and forthright investigation into the issues that she has raised.

Green Pasture has issued a preliminary response here. Interestingly, it makes some of the same points I have made in this article (that biological activity may be a better measure of vitamin D content than quantifying D2 or D3 levels, and that free fatty acids are not an accurate measure of rancidity in marine oils). They are also working on a more detailed response, which I look forward to reading.

One of the lingering issues that Kaayla raised in her report is the finding that the livers used to make FCLO were not from cod, but from Alaskan pollock. I certainly hope Green Pasture addresses this in their upcoming response.

Frankly, I feel that I don’t have the information I need to make a clear decision about whether to continue recommending FCLO. I am in touch with several people with expertise in marine oils, lipid science, and nutritional biochemistry in an attempt to better understand the implications of Kaayla’s report. I will report back to you as I learn more.

In the meantime, I do feel confident in recommending EVCLO from Rosita Real Foods. As mentioned above, they are transparent about their manufacturing process, they post independent lab results (including the names of the labs that performed the tests) on their website, and their product smells, tastes, and looks fresh. They also have an extensive FAQ with answers to many questions about their product and process.

How Concerned Should You Be If You’ve Been Taking Green Pasture FCLO?

Kaayla’s report identifies some issues that deserve further attention, including lower-than-reported levels of vitamins A, D, and K, possible rancidity, and a different ratio of EPA to DHA than would typically be found in cod liver oil.

However, it’s worth pointing out that I have numerous patients whose health noticeably improved after taking FCLO. I’ve heard similar reports from hundreds of readers and podcast listeners, as well as from women who went through my Healthy Baby Code program. In fact, my wife would count herself among this group, and if you search around on the internet, you’ll find testimonials from many people with similar stories.

So, while I do think this report warrants more investigation, I don’t think it is cause for panic. I will continue to investigate this issue and update you when new information becomes available.

Dr. Chris Masterjohn, a nutritional scientist with expertise in fat-soluble vitamins, published his preliminary thoughts on Kaayla’s report. It’s worth reading.


Join the conversation

  1. Since you’re on the topic of CLO, I’d like to ask if you have any knowledge of/information about the Omega Cure fish oil which I’ve been using for several years. Company is Omega Innovations. I’ve not been able to find any reviews/testing.

  2. Gravlax is a fermented fish, fish sauce is a fermented fish and these are traditional. Glycogen is a mammalian form of glucose and is stored in the liver.

    I love my FCLO and HVBO, and now I know much more about it than before, who new Alaskan Pollock is a Cod. I am sure Dave will be changing his description to reflect this understanding.

    I want to know who Dr. Daniels money for the test came from. Follow the money as Sally said in “The Oiling Of America”.

    • Ann, I think Gravlax is cured fish, the recipes I’ve seen needs sugar and salt added. I don’t know about fish sauce, it sure taste yummy to me, but I’ve never heard of people claiming it’s healthy too. Funny I too used the “follow the money logic” on this issue, and I think Sally Fallon is likely to have a lot more to gain than Dr. kaayla Daniel. Dr. Daniel knew she would be facing opposition and come under severe scrutiny when she went public with this and if she really took money from competitor then she knew she’s risking her reputation and her career. I don’t claim to know who’s right and who’s wrong, but if I apply Occam’s razor’s principle that the simplest explanation is probably right, then I would say Sally Fallon and GP got a lot of explaining to do.

    • Gravlax is not fermented, it’s cured with salt (and the process is fairly brief). “Surströmming,” on the other hand is fermented herring and considered a delicacy in northern Sweden. I’m from Stockholm, and have only had it once, but it is very definitely fermented and considered one of the foulest-smelling foods in the world.

      Wikipedia article about surströmming:

      Very funny video from BuzzFeed featuring Americans trying it:

    • Exactly! i read something the other day that Is important in this discussion. Is it true that Fallon’s Westin Price Foundation takes a lot of money from Green Pastures. Couldn’t this influence their recommendation of FCLO?

    • Your point about following the money is the exact reason we’ve stopped our FCLO use. WAPF’s biggest financial contributor is Green Pastures. Talk about following the money! They have every reason to be dishonest.

    • The thing that confuses me is that Kaayla Daniels is a longtime WAPF supporter. She has bucked “the system out there” for a long time. I was surprised that it would be someone who I would expect to support WAPF and any of the connections they have. So, she must have had some pretty big concerns to “in fight”

  3. I used Green Pastures FCLO during a 4-wee Real Food challenge in 2013. My diet was mostly paleo. It was success, judging by
    1. weight loss
    2. improved digestion and overall well-being
    3. inches loss
    4. significant positive changes in blood test numbers, cholesterol etc.
    So, while I might try the Rosita brand sometime, I’m ok with sticking to Green Pastures.

  4. I started with GP FCLO about 5 years ago. I really disliked the consistency and the flavors, but took it daily. It helped my dry skin and cracked heels from the inside out. It’s expensive though and was mail-order-only at that time, so one day I bought Nordic Naturals from my local Whole Foods. It was cheaper, easier to swallow and seemed to do the same job the FCLO had done. When I ran out of Nordic Naturals I bought Carlson’s for the same reasons I had tried Nordic Naturals. Carlson’s also did the same job as FCLO. One day at the WAPF conference in 2012 after having been away from FCLO for many months I took some. My throat burned and I coughed uncontrollably for 30 minutes afterward. My husband had the same reaction. Something had obviously changed with the FCLO. We then started buying the capsules to avoid the burn. But I never noticed a benefit from FCLO after that point. I stopped CLO altogether because I thought maybe somehow I had become “immune” to its benefits. That same day at WAPF, I remember testing some EVCLO at a booth and the person there was explaining to me about FCLO being rancid and that’s why it burned. I said I would keep an eye out for his product once it went to market. I liked the sample of EVCLO and I do believe the booth was Rosita’s. I’m glad one can now purchase Rosita’s. I’ll be giving it a try. Probably not going back to FCLO.

    • I’m not sure if this also applies to FCLO, but look up high quality Extra Virgin Olive Oil. It burns in your throat, very similar to the FCLO. I have tasted very high quality EVOO (with a high anti-oxidant score) and it caused me to cough for some time afterwards. At least in EVOO, the burning sensation is associated with high antioxidant content.

      The cinnamon flavor FCLO especially burned my throat. I switched to the Orange flavor and then the unflavored and those two burned far less. Cinnamon is a “hot” herb afterall.

      But my main gripe is why any company (Rosita in this example) feels the need to bash another company’s product. It is very poor form. It is low-handed and disgraceful. Companies ideally should promote their product for all the virtues of their products, how good they are, test results, color, etc. and let consumers draw their own conclusions.

      As far as I know, Green Pastures has done no similar bashing of the Rosita brand. They *have* educated folks on the intensive processing and synthetic vitamins of nearly all other commercial CLO (Rosita is excluded from this, because they don’t use the same intensive processing methods).

      In other words, it’s not just if you win the game, it’s how you play it. Do you play fair and honorably or do you throw mud and cheat?

      • Exactly,I am sure there are enough customers to go around for BOTH companies without one having to take out the competition in a smear campaign. As for me, this whole thing against Green Pastures stinks and I have stayed with their product. I will not be trying the Rosita product because I don’t trust a company that would handle their PR in this way instead of like you said, the merits of their own product, instead of tearing down another company’s product, to build up their’s.

  5. I’ve been taking Green Pastures FCLO for 10 years. I’m soon to be 69, and have never had any kind of problem/reaction from the FCLO, and I’m the healthiest senior I know. I’m going to continue what works for me.

  6. I have been taking GP FCLO for years and it never occurred to me (until I read Kaayla’s report), that all fermented products that I have ever tasted or made either taste sour (sauerkraut, pickles, kombucha), salty (fish sauce, cheese) or alcoholic/yeasty. This is the flavor of something preserved by good bacteria/yeast.

    FCLO tastes…fishy, strong, oily. But not salty, sour or alcoholic/yeasty.

  7. My experience with Green Pasture Fermented Cod Liver Oil: I decided to make a change after 6 months of extreme eczema rashes covering my body. I ordered 2 bottles of Green Pasture’s Non-Flavored FCLO. Three weeks ago I began taking 4 capsules daily. Skin that was completely raw, red, bleeding, itchy and inflamed is now covered in a healthy matrix of new tissue with just minimal dry skin over top. I would try out Rosita’s EVCLO, too, as it sounds awesome, but I believe I am allergic to Rosemary.

  8. Excellent update Chris. FWIW, here is my N=1 outcome: placebo effect or not I couldn’t say, but I tend to recover very quickly when I take GP FCLO – especially if I’m feeling a little less than 100%, but the “precautionary principal” applies for now and I’ll be switching to Rosita until GP responds. I believe FCLO is an essential food to help us ameliorate some of the ill effects brought about by modern industrial living. Please continue to help us sort this out.

    As a side note, I was a State regulatory investigator for many years. I can say from first hand experience that the current degree of consumer protection is utterly dismal (at best) – more like virtually non-existent. As long a producer doesn’t poison someone (and sometimes not even then), the penalties in most states for making false claims or selling adulterated products are so paltry that they are a complete joke. Cases are routinely settled for minuscule monetary fines that are simply baked into the cost of doing business. The USA desperately needs legitimate oversight of food producers to ensure claims aren’t falsified and that products are not adulterated. It is pitiful that it has come down to sending samples to labs to see what we’re actually buying and consuming. Makes me sick.

  9. The only Cod Liver Oil I use which doesn’t cause an after burp and tastes great is the Lemon Flavored, no Vitamin D added liquid Cod Liver Oil by Nordic Naturals. I have tried many great products but they all cause me to burp after.

  10. I tried Green Pastures FCLO for one full year, on the recommendation of a healthcare practitioner. After the year, I stopped because it made absolutely no difference in my health or how I felt.

  11. Thank you so much for this! We need people like you to make sure companies are selling products that do what they say, and are not just out for the money. We as consumers blindly put our trust in these companies…hoping they are being honest. I use green pastures FCLO everyday and it’s not cheap. I hope I’m not being fooled. Anywho, keep doing what you do, Chris! Blessings.

    • Agree! We need help inbour trusted practiooners to help verify the quality and true impact of our supplements!

  12. Hi Chris,

    I am 7 1/2 months pregnant (32 years old) and I’ve been taking two capsules of the non-gelatin GP FCLO preconception and throughout my pregnancy. With this new informantion at hand, I would like to switch to the EVCLO brand you suggested (until we know more from GP). I noticed on Rosita’s website, it does not mention Vitamin K as an ingredient. Do you know why this is? Do we still get Vitamin K out of the EVCLO? How many teaspoons do you recommend for pregnancy? (Extended question…should taking FCLO/EVCLO plus consuming a couple tablespoons of grassfed butter a day during pregnancy ptevent the need for the Vitamin K shot at birth?) Thank you, thank you!

    • Hi! I took 5-10 caps of FCLO per day through my pregnancy along with some HVBO and organic alfalfa caps. We opted to avoid the K2 shot and my son had absolutely no sign of jaundice and was incredibly healthy. Congratulations on your pregnancy!

    • Hi Cara, congratulations on your pregnancy! I just had my third baby two months ago. My midwife had me take alfalfa capsules starting at 36 weeks, progressively increasing the dose, to help with blood loss and clotting. Alfalfa is rich in vitamin K. I had very little bleeding with delivery and recovered quickly. Good luck to you!

  13. Chris:
    Please allow me to both thank you as well as professionally commend you for your excellent response to Kayla Daniel’s report. Your substantive response and very balanced objectivity is truly appreciated and moreover a valuable contribution to the wellness community.

    While I am optimistic that the issues raised will result in quite a bit of good ultimately I did not want to miss the opportunity to highlight the extraordinary and valuable service you provide to so many.

    Please continue to keep us all informed as many are understandably very eager to receive updates on what is learned.

    Sean O’Mara, MD, JD

  14. Hi Chris,
    I’ve read about the problem with mercury in cod liver fish oil. EVCLO states that it is “real Norwegian cod liver oil” and my understanding is that it is retrieved from cleaner waters. Do you have any concern regarding mercury levels in cod liver oil?
    Thank you.

    • Mercury is not water soluble, so it will never be a problem in cod liver oil, or any fish oil for that matter. What you should be concerned with are fat soluble contaminants like PCBs, Dioxins, pesticides, etc. They actually concentrate into the oil, particularly cod liver oil, unless less stripped out with purification processes.

  15. I am wondering if you take the cod liver oil do you still need to take another source of Omega Three or can you just take the cod liver oil? I cannot swallow those giant pills!!!

  16. Travelling up the coast of Norway in June I was given some cod liver oil. No repeating at all. I had to give up Green Pasture cod liver oil because of the repeating.

    • I have never burped Green Pastures Blue Ice even once in all the years I’ve been using it.

  17. Hi Chris, I’ve been taking the FCLO for awhile now. What always struck me as odd is that I keep the oil refrigerated and when I take it each morning it’s luke warm at best. My question: Is luke warm out of the fridge normal?

    Thanks, Darlene

    • I would get a refrigerator thermometer. Nothing coming out of a fridge should be tepid.

      If it was kept in a door rather than a shelf, it will probably not be as cold there. I would not store milk in the door.

    • I’ve wondered the exact same thing. My FCLO is always luke warm and I keep it at the back of the fridge with my raw milk that needs to stay right at 32 degrees to keep fresh. It’s always seemed odd to me as well.

      • Does it need to be refrigerated? It doesn’t come in refrigerated container. I have some that I’ve had for quite some time from my shipment from radiantlife and I just left it in the box it came in. I figure it’s fermented, so how can it spoil? Am I wrong? Please advise.

  18. I took FCLO when I first learned about it, a few years ago. I did not immediately connect the ensuing chronic throat irritation with taking this until after some time when I had a severe burning in my throat at the time of actually taking it. Then I started to wonder if this was why my throat was inflamed. I stopped taking it and the thrat irritation went away. I also learned of EVCLO and bought this which I have no problem with. The taste of the FCLO was truly disgusting.

  19. Of course, because I just ordered a bottle of cinnamon tingle 3 days ago.
    And response to my question (email) regarding spoilage according to manuf date was as follows:

    “All of our oils are very stable and will not be adversely affected by ambient temperatures.

    The fermented oils will continue to digest, or change, over time which may change the color, taste, smell or texture. Refrigeration will slow this process, but all of our oils are very stable and do not require refrigeration; even after opening. We do not believe these oils are even capable of going bad or becoming rancid.

    Previously we used an expiration date that was dated two years out from the date of manufacture.

    With best wishes,

    Green Pasture”

    • The content of the email is quite disturbing. These oils are inherently unstable, that means that if they can’t go rancid, they already are rancid or there is so much preservative in them that they are non-functional.

  20. I tried several flavors of Green Pasture’s FCLO and always had the same result – acid reflux, nausea, headache, and just over all not well shortly after consuming. Believing this was a safe product that was good for me, it took me a little while to pinpoint the FCLO as the culprit. Now I stick with Carlson Norwegian CLO and have no problems.

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