Important Update on Cod Liver Oil

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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.

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.

Now I’d like to hear from you. What has your experience been with FCLO? Have you tried EVCLO? Did you notice a difference in how you felt after switching? Let us know in the comments section.

Note: I earn a small commission if you use the links in this article to purchase the products I mentioned. I only recommend products I would use myself or that I use with patients in my practice. Your purchase helps support this site and my ongoing research.

Filed under: Fitness