Five truths about fermented cod liver oil

29 March 2016 
By: Katrina

As part of its extensive product range, GPA Wholefoods (the best organic supplements in Australia) offers the popular Green Pasture Products Blue Ice Fermented Cod Liver Oil (FCLO) nutritional supplements, which are highly recommended by the Weston A Price Foundation (WAPF).

In recent years, some within the wholefoods and nutrition sector have questioned the benefits of FCLO, and raised a number of questions about the purity and effectiveness of the product. 

One of the more prominent of these voices has been Dr Kaayla T. Daniel, PhD. In August 2015, Dr Daniel published a free e-book, Hook Line and Stinker! The Truth About Fermented Cod Liver Oil, denouncing the health benefits of FCLO.

The publication raises a number of serious questions and concerns about the nutritional integrity and benefits of FCLO, and makes a range of highly negative claims, including that FCLO is rancid, adulterated, made from fish other than cod and does not contain the high levels of fat-soluble vitamins and fatty acids that it purports to. 

In 2014 and 2015, Damien Armstrong, Co-Director and Technical Manager of GPA Wholefoods, visited the Green Pasture Products manufacturing facility in O’Neil, Nebraska to ensure that products were being manufactured to the suppliers stated methods and standards. Damien was give an all-access tour and was authorised to view any part of the facility he wished and to ask any questions about any materials or equipment he saw onsite. Damien witnessed the full manufacturing process for Blue Ice™ Fermented Cod Liver Oil from start to finish, including visiting the pharmaceutical manufacturer contracted to package the product, and visiting the independent scientific testing laboratories to overview the testing procedures in action.

A number of responses to Dr Daniel’s book have been published online, including from the Weston A. Price Foundation (WAPF). 

As a further response to these negative claims, this paper outlines five truths about Green Pasture Products Fermented Cod Liver Oil. This is supported by evidence from Green Pasture Products, the WAPF and other third parties as indicated, to highlight the many benefits of FCLO and the evidence to support our position that FCLO is a highly nutritious, safe and effective nutritional supplement.


Green Pastures Blue Ice Fermented Cod Liver Oil is made in small batches with extraordinary care. We ferment livers from fish that have been exclusively wild caught in the Bering Sea/Aleutian islands region.’

One of the negative claims about FCLO is that it is made from the livers of fish other than cod (such as Alaskan pollock) and as such is not actually ‘cod liver oil’ and therefore does not contain the high nutrient value that it is claimed to have.

Further, there have been claims that FCLO is made from farmed, rather than wild-caught fish. These claims have serious ramifications, both for the nutrient profile of FCLO and the integrity of the product.


  • Alaskan pollock (also known as walleye pollock) is a common name for one species of fish in the Gadidae family—Gadus Chalcogrammus. However, this fish is NOT a pollock. 
  • The United States Food and Drug Administration (FDA) provides a definition of cod, and has determined (through improved DNA testing technology), that Alaskan pollock belongs in the cod family. 
  • Seven different species of fish are listed under the family name Gadidea, including various cods, pollocks, haddock and hake, and the genus name for Alaskan pollock is now Gadus, the same as the cods.
  • Green Pasture Products recently updated their product information and labels to include the species name from the Gadidae family that is used in their cod liver oil products, clearly stating that their product is made from wild-caught cod: 

Contains: Cod (Gadus macrocephalus Pacific Cod)

It should be noted that this is not a requirement of the FDA or World Health Organization (WHO), but that Green Pasture Products are the first company globally to list species names on their products.

Image : The Truth Behind Fermented Cod Liver Oil 


The FDA, WHO, Codex Alimentarius International Food Standards (CODEX), and Food and Agriculture Organization of the United Nations (FAO) allow for many other species of fish to be classified as cod.


‘Fermentation is a natural enzymatic and microbial action that releases the oil from the livers.’

Fermented fish products are not a new idea. They have been made and consumed in traditional cultures for thousands of years and used all over the world for their many profound health benefits.

In traditional Tahitian culture, shark livers were placed in the stomach of the shark, hung from trees and allowed to ferment in order to yield the oil they contained. In Norway, traditional cultures placed cod livers in salted barrels with brine, and after a period of six months, harvested the oil that rose to the surface of the barrel.

Image :  Kay Baxter, The Fat –Soluble Activators by Sally Fallon Morrell,.

One of the most strident claims against Green Pasture Products Fermented Cod Liver Oil is that it is not actually fermented. The basis for this argument is that the fermentation process cannot occur without carbohydrate and that cod livers lack sufficient carbohydrate for fermentation to take place. 

In addition, some have protested that oils cannot be fermented—which is true. But the name ‘Fermented Cod Liver Oil’ was derived from the process to extract the oil from the liver. The livers are fermented, not the oil. 

There are three ways to rupture the cell walls of cod liver tissue to extract lipids: 

  • temperature (either heat or cold fracturing)
  • chemical
  • fermentation/digestion.

The first two methods (temperature and chemical) are common ‘industrial’ approaches—quick and efficient, but damaging to the nutrient content of the foods.

Fermentation/digestion is a natural process of bacterial and enzymatic breakdown that produces foods which are pre-digested, more readily consumed and used by human bodies, while retaining a stronger or broader essence of the original product. 

In the case of fermented cod liver oil, the process is not complicated but does take time to complete. It is simply an enzymatic and bacterial digestion of the liver releasing the oil. Or, in simplistic terms, it is essentially the same process that takes place in one’s digestive system. 

The result is a light to dark brown cod liver oil that has hundreds of thousands of molecular structures bound within the fatty acid structures. There are ways to lighten the oil but this would include adding preservatives to the vats (preventing the natural process), or running the product through a variety of bleaching or earthen material, which would cause stripping of the pigments and waxes.


  1. The frozen cod livers are added to fermentation vats along with Green Pasture Products starter culture, salt and water. The vats are then sealed and allowed to ferment. This process—which can take up to 12 months—produces three distinct layers within the fermentation vats:

a.    At the bottom of the vat is the solid liver material and sediment. 

b.    On top of this is a water layer, which is formed as water is released from the cod livers during fermentation. 

c.    On top of the water, an oil layer is formed. 

  1. After the fermentation is complete, the top layer, containing the oil, is pulled from the fermentation vat and centrifuged to remove all sediment and liver material, and to separate out any water that was pulled from the vats with the desired oil.

The Green Pastures starter culture used in FCLO products is a proprietary blend developed over years of testing and research by Green Pasture Products.


In October 2015, Jacob A Friest, PhD Organic Chemistry, 2015 Chair of the Nebraska Section of the American Chemical Society released an independent scientific evaluation of Green Pastures Fermented Cod Liver Oil products. His report: Fermented Cod Liver Oil (FCLO): Investigation of Green Pastures Fermentation Process and Food Safety Implications, concluded:

  • ‘Green Pastures does not claim, neither do they advertise, that their product is produced by the fermentation of cod liver oil, but by that of the carbohydrates found in the whole cod livers themselves. 
  • cod livers contain between 1 and 2 grams of carbohydrates for every 100 grams of liver. Typical fermentation processes only require 0.62 grams of carbohydrate per kilogram to lower the pH by 0.1 pH units1. Based on the 1 to 2 grams of carbohydrate/100 grams of liver, this would give rise to a total drop in pH between 1.6 to 3.2 pH units. If we assume that the process of fermenting a cod liver begins at neutral pH of approximately 7.0, the natural levels of carbohydrate found in cod livers would be sufficient to lower the pH of the final fermented product batch to between 3.8 and 5.4.’’ 
  • This brings us to the question of what is an acceptable pH range to achieve a safe-for-human consumption product? Dr. Daniel asserts that the pH needed to prevent food spoilage for true lacto-fermented product is less than 4.6. However, as published by the Food and Agriculture Organization of the United Nations (FAO), raw fermented sausages are only moderately acidic with a pH range of 5.0-5.5 and are safe for human consumption. 
  • In her article Dr. Daniel indicates that the pH of the bottled FLCO product is between 5.17 and 6.0. After questioning David Wetzel about Green Pasture’s fermentation process, these numbers are as expected and in no way disprove that effective levels of fermentation were achieved to ensure product safety.’ 


Dr Friest’s evaluation shows that pH values for FCLO fall well within the normal pH levels accepted for the fermentation of raw meat products, as described by the FAO:

‘It is important to understand the layers formed during the fermentation process and how the oil is separated/purified by centrifugation to understand why the FCLO pH falls outside the normal pH range for fermented animal meat products. This is because the major acid by-product of a lacto-fermentative process is lactic acid. 

Lactic acid is a highly water soluble acid and is extracted from the resulting oil during the pulling and centrifugation of the oil. To be certain of this, Green Pastures has measured the pH of the resulting water layer (brine) at the end of the fermentation process and found it to be between 4.8 and 5.04.’


‘Our fermented cod liver oil is a raw, unadulterated, whole food. There are no additives of any kind. It is routinely third-party tested for purity.’

According to Green Pastures’ product information, Green Pastures Fermented Cod Liver Oil is:

  • 100% raw 
  • produced by age-old traditional methods—fermented for up to 12 months in large stainless steel vats, without the use of any heat, making the oil extremely stable
  • completely free from synthetic vitamins 
  • naturally rich in EPA, DHA, Omega 3 and Vitamins A and D.


FCLO is tested:

  • before it leaves the Green Pastures Products manufacturing site, to ensure the product is suitable for use
  • upon arrival at pharmaceutical packaging company, to ensure no contaminated or substandard product enters production line
  • immediately prior to being packaged
  • every six weeks that it is in storage at the packaging facility, to ensure no degradation in quality, or contamination.

In addition, FCLO samples are randomly tested from the production run and also during and after packaging. Samples are also retained from every batch in the event that further testing is required.


‘Blue Ice™ Fermented Cod Liver Oil provides ample amounts of the fat-soluble vitamins A and D in their most readily absorbed forms, and the inflammation-reducing, and brain and nervous system-supporting, Omega 3 fatty acids, EPA and DHA.’


Fish do not receive vitamin D from the sun. Vitamin D is present in oceanic environments via organisms such as phytoplankton and zooplankton, both of which contain Vitamin D2 and D3. At present, very little is known about the pathway of Vitamin D in fish and its effect on the food chain. Overall, we are in the infancy of understanding the origin of vitamin D in the sea. While measuring Vitamin D is difficult, from the research that has been completed to date, it appears a variety of forms of Vitamin D are present in FCLO, including D2 and D3.  

Measuring the nutrient content of FCLO

Vitamin D content We currently know of around 500 types of naturally occurring Vitamin D, and some scientists have estimated there could be as many as 6000 naturally occurring types. However, most (if not all) laboratories only test for only one or two types of vitamin D. According to Green Pasture Products:

Nutrient assays, including vitamins A and D, for our fermented oils vary widely depending on methodology, lab and batch. Current science struggles to answer the questions we have on our sacred fermented foods.

There are many naturally occurring metabolites and co-factors that make the issue of measuring natural nutrients difficult in the fermented oils. We do know that historical cultures liberally consumed these sacred foods to great benefit without today's standardization of knowledge.’


Green Pastures fermented cod liver oil characteristically contains the following nutrient levels. While these amounts are typical, the ratios naturally vary from batch to batch, as with any fresh/unprocessed food.

  • Vitamin A 1825IU, Vitamin D 426IU per 2 caps (or per 1ml)
  • EPA 150mg and DHA 90mg per 2 caps (or per 1ml).


Research shows that trans fats are a naturally occurring part of many marine-based oils, including cod. 

A 2008 French study examined seafood consumption in some French coastal communities and the fatty acid composition of seafood. Further, a report published in 2014 by the Oriental Journal Of Chemistry—Fatty Acid Composition of Some Potential Fish Oil from Production Centers in Indonesia, confirms the presence of naturally occurring trans fats in marine oils. Earlier research from Japan has also shown that naturally occurring bacteria found in fish viscera produced trans fatty acids.

The Weston A Price Foundation ordered tests of its own, and other major brands of cod liver oil on the market and found that trans fats were present in all samples.

A scientific analysis conducted by Subramaniam Sathivel PhD, Professor of Food Engineering at the School of Nutrition and Food Sciences and the Department of Biological and Agricultural Engineering, Louisiana State University Agricultural Center (LSUAC), was published on the Green Pastures website on November 20 2015. This report reviewed the laboratory test results produced by three commercial analytical laboratories of CLO samples from Green Pastures and five other cod liver oil brands. The report concluded that, while there are low amounts of trans fatty acids naturally present in fish, the amount contained in FCLO is minimal and highly unlikely to exceed recommended daily consumption:

‘Your company’s oil samples had a TFA average of 1.21%+0.51 (ranged from 0.54 to 2.01), the other commercial cod oil's TFA ranged from 0.26% to 2.13%. The report from the Eurofins Nutritional Analysis Center indicated that your company’s oil contained 0.81%+0.23. Merieux Silliker Laboratory report showed that your company’s oil had 0.60%+0.10 (ranged from 0.50 to 0.75) TFA and that the other companies’ oils had a TFA range from 0.65 and 0.90%.’\

‘According to the Department of Health in the United Kingdom, TFA consumption should not exceed 5 g/day (United Kingdom, 1994). Your oil contained relatively a low level of TFA (an average of 1.21%). At this level, it would require about 413 g of cod liver oil to reach the 5 g TFA limit. In general, about two full cups of fish oil per day exceeds normal consumption levels.’


The process of fermentation is a similar process to digestion. Enzymatic and bacterial processes break down cell walls and improve the digestibility of food and the bioavailability of the nutrients it contains. Yoghurt and cheese are common and widely used fermented products with universally recognised nutritional benefits. We do not refer to these foods as rotting or rancid. 

In the case of Fermented Cod Liver Oil, the fermentation process is simply the bacterial/enzymatic digestion of the cell wall to release the lipids from the cellular structure. Therefore, any suggestion that this naturally fermented product is rancid or rotting is both highly misleading and untrue.

The Weston A Price Foundation distributed samples of FCLO for testing to Midwest Laboratories and the Leicester School of Pharmacy. These tests showed that FCLO had no lipid peroxide species and is safe.

In addition, an independent review and evaluation of Green Pasture Products product testing and food safety by Dr Jacob Friest—PhD Organic Chemistry, and Chair of the Nebraska Section of the American Chemical Society—provides further proof that the product is not rancid. Dr Friest’s review concludes that:

‘Testing of FCLO by Midwest Laboratories and Eurofins Nutritional Analysis Center clearly demonstrates that FCLO is safe for human consumption and displays no signs of product rancidity or significant levels of biogenic amines. A critical analysis of Dr. Daniel’s testing regarding the safety of Green Pasture FCLO, in fact, demonstrates the safety of FCLO as well as the thoroughness in which it has been tested to prove it as such.’ 


The negative claims that have recently been circulated about FCLO are not backed by rigorous research and/or and based on insufficient scientific testing and research. Rather, these criticisms are founded on bias, opinion and the deliberate misinterpretation of data.

In addition, there are conflicting commercial interests at play in this area that may be influencing certain claims against FCLO. 

While we acknowledge that there are differing opinions circulating about FCLO, GPA believes in the product and stands by it for the following reasons:

  1. None of the negative claims made about FCLO are supported by the extensive independent analysis, testing and scientific research that we have consulted 
  2. We observe that the product is made under rigorous production values and has undergone scrupulous product testing.
  3. Damien Armstrong, Co-Director and Technical Manager of GPA has personally inspected Green Pasture Products manufacturing facility in O’Neil, Nebraska to ensure that products were being manufactured to the suppliers stated methods and standards. In addition, Damien witnessed the full manufacturing process for Blue Ice™ Fermented Cod Liver Oil from start to finish, including visiting the pharmaceutical manufacturer contracted to package the product, and visiting the independent scientific testing laboratories to overview the testing procedures in action. 

As a result, we at GPA stand by this product and have full confidence in continuing to supply it to our customers.



The case against:

Background/product information:


Scientific reports, reviews and analyses:




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