Is Fermented Cod Liver Oil Safe or Rancid?

Katie Wells Avatar

Reading Time: 9 minutes

This post contains affiliate links.

Read my affiliate policy.

Fermented Cod Liver Oil- Safe or Rancid
Wellness Mama » Blog » Health » Is Fermented Cod Liver Oil Safe or Rancid?

I’ve written in depth before about the supplements I personally take, which for a long time included fermented cod liver oil.

If you follow many bloggers in the natural health community, you’ve probably seen the recent drama about the potential quality issues with fermented cod liver oil. I delve into this in depth below but the summary of my personal current opinion on the issue is that:

  1. There is conflicting evidence on the safety of fermented cod liver oil (and more recently even on the safety of any omega-3 supplements) that warrant more research.
  2. Health and nutrition continue to become more and more personalized so what works for me is not likely to work for you and vice versa.
  3. I personally am focusing on getting all nutrients from food whenever possible and with rare exception and am sticking to foods like sardines and other low-mercury fish in place of supplements.

It is important to note that this is strictly my personal opinion and is in no way close to medical advice (nor is any information on this website). As always, I encourage you to do your own research and due diligence on any health related decisions.

FCLO Drama…

Fermented Cod Liver Oil is considered a traditional food that has been recommended by the Weston A. Price Foundation and many real food bloggers (including me) for years. It was even the WAPF recommended brand for use in homemade infant formula and many members take it religiously.

On August 21, 2015, Weston A. Price Foundation Vice President Dr. Kaayla Daniel released a 100+ page report detailing the results of independent lab tests that she had on samples of Green Pastures Fermented Cod Liver Oil and that alleged major issues with the brand, including rancidity, lower levels of nutrients than were claimed, and sourcing issues.

Dr. Daniel’s report claims that FCLO is not actually fermented, is rancid, putrid, and adulterated with other (cheaper) oils. It also alleges that there are lower levels of fat soluble nutrients in FCLO than claimed and that the oil isn’t even from cod. Serious claims from a well-respected person in the real food community.

Understandably, this has left many people in the real food community reeling and looking for answers. I’ve gotten many emails, comments, and social media messages in the last few days asking what my take on the subject is, and have spent a lot of time researching this myself.

Below is my personal opinion and research on this issue based on the information available right now. I will continue to update this post as more information is revealed.

My hope is that no matter the outcome of further research and study about fermented cod liver oil, the real food community will take this as a lesson in the importance of verifying the quality of supplements and use this as an opportunity to improve the real food movement, rather than to divide the community.

Is Fermented Cod Liver Oil Safe or Rancid?

In short… I don’t know.

Based on the information available from both sides, I don’t think it is possible for anyone (short of Green Pastures, the company producing the fermented cod liver oil in question) to know the answers to all of the questions that many people are asking right now. At the same time, there are some holes in the report from Dr. Daniels and some potential financial ties that have come to light that call her motivation into question.

When our family first started taking fermented cod liver oil years ago, I did a lot of research on the company and on cod liver oil in general (as anyone should do before taking fat soluble vitamins regularly). The only lab reports I was able to find at the time were from Green Pastures and they showed no rancidity in the fermented cod liver oil and verified that FCLO did contain the fat soluble vitamins it was known for.

The recent report from Dr. Daniel calls these tests into question. Her results have the lab company and the party funding the test blurred out, which is somewhat suspect, though I do not think that this necessarily discredits the information in the reports. The report does, however, make some assertions about certain compounds being harmful as a justification for why FCLO is not safe, and some of these claims are not backed by existing science (or are at least controversial).

In the last six months or so, I’ve actually been researching and testing different forms of cod liver oil after readers have inquired about different brands and reported issues they’ve had with FCLO.

My Experience

Our family has seen benefits from taking fermented cod liver oil over the years, including reversal of tooth decay. I’ve also noticed that my skin is naturally more sun tolerant since taking FCLO, probably from the fat soluble vitamins it contains.

At the same time, there is the possibility that the quality of Green Pastures FCLO has changed since I researched it years ago, or that more recent lab testing has been able to reveal problems that were undetectable years ago.

Fermented Cod Liver Oil: The Claims

FCLO is Not Fermented:

There may be some truth to this claim. I’ve talked before about the importance of fermented foods for health, and why the naturally created beneficial bacteria in fermented foods are so important.

The red flag that Daniels explains is that oil cannot ferment. The process of fermentation requires the presence of a carbohydrate as the food for the fermentation process. Many people (including me) assumed that an unnamed carbohydrate was used for the fermentation process but was removed by the process so it was not listed on the ingredients or that the livers themselves were fermented and not the oil (as an oil can’t ferment without another ingredient).

Green Pastures owner Dave Wetzel has been less than transparent about this fermentation process, though supposedly he has brought several WAPF members and high profile bloggers to his facility to see the process and verify its quality. (I have never been to the facility and have no firsthand knowledge of this process, so I have to rely on Dave’s explanation of his process).

This is one area that I hope we see more detail on from Green Pastures and from independent sources in the future. For now, the debate about the process used and what part of the process actually requires fermentation does not necessarily mean that the final product is not high quality, but it does raise some interesting questions to explore.

FCLO is Rancid:

Fats and oils cannot ferment without carbohydrates, so what happens when they are exposed to the conditions of fermentation? In short, they go rancid.

This is the basis for the claims in the new report. The independent lab results from Dr. Daniel show several biomarkers of rancidity in the samples tested (these were not present in the reports I found in my initial research).

In Daniel’s tests, peroxide, free fatty acids and other biomarkers of rancidity were found. I was unable to find clear answers directly from Green Pastures, though I found several older articles and interviews in which Dave states that his product does not contain these biomarkers or that the substances are not harmful. Again, more research is needed from independent sources on this.

Low Levels of Vitamins:

Another claim in the reports is that FCLO contains less fat soluble vitamins than claimed and that the Vitamin D is in the form of D2 and not D3.

The common consensus among medical experts is that D3 is the preferred form, though Green Pastures claims that D2 is equally safe and effective. To be fair, all forms of cod liver oil contain higher levels of D2 and this does not necessarily raise a red flag, but again, more research is needed.

Also, Green Pastures has never made claims, to my knowledge, about the levels of nutrients in their products, carefully explaining that they are a food product and that levels can change.

Not Actually Cod:

The report further claimed that the DNA tests on Green Pastures products showed that the livers used were from Alaskan Polluck, not cod. This seems to be partially an issue of understanding of fish species and families, since:

The Alaska pollock or walleye pollock (Gadus chalcogrammus, formerly Theragra chalcogramma) is a marine fish species of the cod family Gadidae. Alaska pollock is a semipelagic schooling fish widely distributed in the North Pacific with largest concentrations found in the eastern Bering Sea.

After hours of research, I could not find any definitive answer directly from Green Pastures about the origin or species of the fish they use. The closest I could find was Dave’s vague answer from his own FAQs:

Ok, The question arises on the topic of location of the fish. The fish school in the northern, cold waters around the Arctic Ocean. They do not have a nationality and a fish can school for a 1000+ miles in its life. So the relevance of the specific spot the fish is cleaned is not relevant to the discussion, ‘is the fish safe to consume’.

Red Flags from the Report

While Kaayla’s report certainly raises some concerns about FCLO, it also raises some concerns about its own validity. For instance:

  • The labs used for the testing and who paid for the independent testing is not disclosed. This isn’t necessarily a red flag on its own, but given the rumored history of drama within the WAPF organization, I think it deserves further investigation. Given how much heated press this report has generated, I can certainly understand the potential desire of a donor to remain anonymous in the report,  but it does raise a red flag.
  • Though I have no firsthand experience with any of the board members of WAPF, including Sally Fallon or Dr. Daniel, reports of internal drama run rampant in the real food community. In fact, I avoided joining the WAPF for years partially because of these claims. We have not heard an official response from WAPF or Green Pastures yet, and I think that thoroughly evaluating both sides will be an important step for any of us looking to understand the long term validity of these claims.
  • The one funding source that Kaayla mentions in the report, Dr. Ron Schmid ND, has a long and somewhat dramatic history with FCLO. He reportedly took (really large doses- above the recommended amount) of regular cod liver oil and then fermented cod liver oil for decades and attributes them to his severe heart disease. He has also stated publicly that he attributes his miraculous recovery from heart disease with discontinuing taking FCLO. Not exactly an unbiased source. Again, this does not discredit the information, but does raise some additional questions.
  • While Daniels lists sources for many of her claims, she doesn’t list her sources for many of her quotes. In fact, while she says she talked to many experts (including “top university professors, scientists, researchers, lab managers, doctors and other health care practitioners”), these sources are unnamed for many of her more serious allegations. Obviously, these claims would carry much more weight if they were substantiated and sourced.
  • It also raised a red flag for me that Daniel has a call to action for her own services in the report, saying: “Finally, if you think you have health challenges related to FCLO consumption, share your story with friends, colleagues . . . and me. If you think you’ve been harmed, I would like to offer you a FREE mini appointment by phone or face-to- face on Skype. To share your story or to make your appointment, contact me at ***********” I can understand her desire to help others if she truly feels that FCLO is harmful, but a report making these allegations does not seem like the appropriate place to make this offer. Again, not a reason to discredit the report, but a red flag.
  • Emerging information has also revealed some potential political ties from the new organization Dr. Daniels founded after leaving/being forced out of WAPF and the makers of the Extra Virgin Cod Liver Oil product she recommends. In other words, the company she recommends as an alternative to FCLO is a sponsor of her new organization so she may have a bias here. Additionally, there is a lot of information floating around about potential conflict within the old organization hierarchy of WAPF that suggests there may be much more to the story on both sides.

The Bottom Line

Based on the available information at this time, it is extremely difficult or impossible to draw a definitive conclusion on the issue of the quality of Green Pastures FCLO or other CLO products. I think that this whole “scandal” is a symptom of a much bigger problem- the mud slinging between competing companies and emerging attacks on both sides of the fence.

The report brings up some serious points and hints at some possible misleading information from Green Pastures over the years. As a mom who has given FCLO to my own family for years and seen good enough results to share my experience with you, I am extremely angry and disappointed in Green Pastures if any of these claims turn out to be true. At the same time, there are some serious holes in the Dr. Daniel’s report and the potential financial ties to the new company bring up more questions.

I think more research and disclosure is needed from both parties, and like I said, I hope that all of us in the real food community will use this as an opportunity to improve, learn more, and get to the truth, and not as an excuse to argue and divide.

At the end of the day, I have to hope and trust until I see evidence to the contrary that both the founders of Green Pastures and Dr. Daniel are interested in health and serving their communities and continue to evaluate any information as objectively as possible.

At the same time, I don’t think either side is unbiased.

Green Pastures, of course, derives a profit from the sale of their FCLO. Dr Daniel has a rumored history of contention with different parties within WAPF and with Green Pastures as well as potential financial ties to the new EVCLO company. Again, none of these are relevant to the validity of the data in the reports or even necessarily to the motivation of either party, but they do provide a possible motivation for slanting information one way or the other.

At the end of the day, things are rarely what they seem on the surface and my guess is that we will continue to find more from both sides of this story.

What Our Family is Doing

As I mentioned, after many reader questions, I have been researching FCLO and alternative cod liver oil sources for months.

Since there is so much conflicting information on the issue right now, please share any information or research you’ve found in the comments below. Has your opinion of FCLO changed as a result of this report?

Katie Wells Avatar

About Katie Wells

Katie Wells, CTNC, MCHC, Founder of Wellness Mama and Co-founder of Wellnesse, has a background in research, journalism, and nutrition. As a mom of six, she turned to research and took health into her own hands to find answers to her health problems. is the culmination of her thousands of hours of research and all posts are medically reviewed and verified by the Wellness Mama research team. Katie is also the author of the bestselling books The Wellness Mama Cookbook and The Wellness Mama 5-Step Lifestyle Detox.


329 responses to “Is Fermented Cod Liver Oil Safe or Rancid?”

  1. Feruza Avatar

    Any oil can go rancid and it goes rancid very fast (in my experience). Even Rosita cod liver oil got rancid in my fridge after a few months. I wonder if the oil is shipped during summer time it goes rancid faster due to summer heat? I guess this was the case for me with both FCLO and Rosita.

  2. Prof. Paul Schultz Avatar
    Prof. Paul Schultz

    I am sixty five, a male, and taking FCLO from Green Pastures for a month with no real evidentiary cavity healing noticed. Having examined the following website
    Look at the sponsors “as seen on tv.” That tells me all I need to know this is all political disinformation to bring someone (Green Pasture) down in my humble opinion.

  3. Rhonda Avatar

    my holistic dr does not recommend cod liver oil from any brand as for variety of reasons.
    I’ve seen some of it addressed on nutri- spec website.

  4. Galia Avatar

    Many people don’t seem to understand the process of fermentation in general and this seems to be where a lot of the confusion is coming from.

    As an analogous example, cultured butter is not itself actually cultured, but simply comes from clabbered milk. It therefore has many more beneficial organisms than butter made from a mechanical extraction of the cream from the milk, with no culturing in the process.

    In the same way fermented cod liver oil comes from the fermentation of the liver and not the fermentation of the finished product/oil. This is obvious to any person familiar with fermentation of foods. But I can see how it can easily be misunderstood by someone with no knowledge on the matter and with just a literal reading and interpretation of the words.

Older Comments
1 8 9 10

Leave a Reply

Your email address will not be published. Required fields are marked *