FAQs: All about fermented cod liver oil (and why I don’t take fish oil)

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A note from me before you delve into this extensive Q&A on fermented cod liver oil:

Fermented cod liver oil is the only “supplement” I take regularly and I recommend it for others as well. I first learned of this product several years ago while beginning my nutrition studies and while weighing the differences between it and a standard omega 3-rich fish oil supplement. I chose to move forward with FCLO and, based on my continued studying and research on the topic, will remain taking FCLO and not an isolated polyunsaturated fatty acid / omega 3-rich fish oil.

Additionally, when I dug into the research for this post, I ended up taking myself down a bit of a rabbit hole and discovered more resources than I thought would exist on the production of not only fermented cod liver oil and cod liver oil, but also fish oil. In my research I’ve discovered that the industry around and production of fish oil is enormous and is very much like that of seed oils. I’ll do my best to delve more into these topics in a follow-up post to this one in the very near future, but I didn’t want to delay sharing this one as wading through the rest of the information I’ve discovered will take me some time.

Please note: With this post, as with anything you read on this website – the information is not intended to be a replacement for professional medical advice, diagnosis, or treatment. Understand that tens of thousands of people read this blog, and I am not able to tell every unique reader a specific dose that is right for you, your family, or your friends. This is information for you to use to form your opinion and take action thereafter – or not. 


Chris Kresser, L.Ac

Chris Kresser, L.Ac


“Fermented cod liver oil is the one supplement I think nearly everyone can benefit from. I’ve seen it clear acne, lift depression, balance hormones, and reverse autoimmunity. I use it myself and recommend it to all of my patients.” – Chris Kresser, L.Ac.


What is fermented cod liver oil (FCLO)?

Fermented cod liver oil is a cold-processed form of oil that is gently made from cod livers. The fermentation process allows the oil to be separated from the livers without damaging the vitamin or polyunsaturated fatty acid (omega 3/EPA/DHA) content of the oil. This oil is then gently purified and then combined with flavorings (except in unflavored varieties) and bottled or placed into capsules.

There is currently only one company producing fermented cod liver oil that we know of, Green Pasture – many people find the cinnamon flavor most palatable. (Note: Balanced Bites is not affiliated with nor sponsored by Green Pasture in any way.)

How is FCLO different from standard cod liver oil or fish oil?

fcloVSfishoilSQProcessing is everything. Cold processing and fermentation protect the naturally occurring nutrients (omega 3 fatty acids as well as vitamins A & D) present in cod liver oil, however, heat processing will damage them.

In order to make use of nutrients that we eat in our foods, a reduction process needs to occur. We consume macronutrients (protein, carbohydrates, and fats) and micronutrients (vitamins, minerals, and phytochemicals), but the end usable form of these constituents are the metabolites of each: amino acids, glucose, and fatty acids and the individual molecules that make up the micronutrients.

In our bodies, digestive breakdown is the mechanism by which we do this internally – by means of not only the physical churning in our stomach, but also by means of stomach acid, bile, and, perhaps most notably digestive enzymes.

There are several ways in which the reduction of nutrients may occur: heat, synthetic chemical processing, and digestion (or fermentation, which is an exogenous means of pre-digesting nutrients).

Heat is damaging to delicate nutrients, especially when they are isolated from their whole-food source.

Synthetic chemical breakdown of nutrients is damaging as well. 

Digestion or fermentation (enzymatic breakdown) is by far the safest and most effective way to reduce the molecular structures in foods to their end usable constituents.  (If you are an organic chemistry-buff, perhaps you’ll know a lot more about what the following information means than I do) When reduction is initiated by digestion (digestive enzymes) or fermentation, 100% of molecules break “to the right” – which is how our body uses them best. When the reduction is initiated by either heat or synthetic chemicals, 50% of the molecules break to the left (which may be toxic or unhealthful at the very least) and 50% to the right.

I will get into a lot more on the differences of the processing and production of fish oil, cod liver oil, and fermented cod liver oil in a post in the very near future as I noted in my introduction. This is a big topic and deserves its own post. 

For more information on this redox process, check out the source of the information I just provided above in the video below from Dave, owner of Green Pasture.

How is fermented cod liver oil different from an omega 3-rich fish oil in nutritional content?

The main goal or focus of supplementation with fish oil is to increase your omega 3 fatty acid intake whereas the main goal or focus with fermented cod liver oil is to increase your intake of fat soluble vitamins that are critical for immune health – including vitamins A, D, and K2 – in ratios that are appropriately balanced for ideal nutrient assimilation from this whole-food source.

While there is omega 3 (Eicosapentaenoic acid – EPA, and Docosahexaenoic acid – DHA) content to fermented cod liver oil, the amounts are not concentrated to supply high doses of these fatty acids.

Furthermore, the primary benefit of fermented cod liver oil is the concentrated presence of naturally occurring fat-soluble vitamins: A, D, E and K2 that are scarce in modern diets. There are omega-3 fatty acids in fermented cod liver oil (FCLO), however, the cold processing, fermentation, and concentrated food-form of this supplement make it a much safer and more health-promoting option than isolated PUFA available in traditional fish oil supplements on the market.

I consider fermented cod liver oil to be more of a concentrated superfood than an isolated nutrient supplement. Some of the many other nutrients found in fermented cod liver oil include: CoQ10 (also rich in heart tissue and some fish like sardines) and various quinones (known for anti-tumor, anti-microbacterial, and anti-cardiovascular disease properties). There are potentially thousands of other unspecified nutrients within this concentrated superfood.


“One gram per day of omega-3 fatty acids from fish oil reduces cardiovascular mortality in patients with chronic heart failure or who have recently had a heart attack. However, fish oil may increase cardiovascular and total mortality, especially when used for more than four years in combination with a standard modern diet.” – Chris Masterjohn


What is the omega 3 content of fermented cod liver oil?


Click to view larger.

The funny thing about a whole-food “supplement” is that it’s not produced with the same type of exacting methods as other highly refined omega 3, isolated PUFA oils are, so determining an exact EPA/DHA content is not quite so simple. Furthermore, the value of fermented cod liver oil (FCLO) is not primarily its EPA/DHA content, though it contains whatever amount is naturally occurring, not concentrated/isolated. According to Dave Wetzel, owner of Green Pasture:

15% of FCLO will naturally be EPA
10% of FCLO will naturally be DHA

1 teaspoon of ~5000 mg of total oil in 1 tsp
1 tsp contains approx 500mg of DHA
1 tsp contains approx  750mg of EPA
1 tsp contains approx 1250mg TOTAL of EPA/DHA omega 3 (or 1.25 grams)

500mg of fermented cod liver oil per capsule
8-10 capsules = 1 tsp

Skate liver oil contains slightly more EPA/DHA per serving than fermented cod liver oil at 15-16% DHA, 12% EPA.

Information isn’t labeled because the industry is touting claims of the EPA/DHA content in fish oils, which, after processing/industrializing, the product is void of many nutrients and all that remains are EPA/DHA – so that is what is marketed. Farmed fish can change the fatty acid profile of an oil.

photo credit: http://nourishingourchildren.wordpress.com/

photo credit: http://nourishingourchildren.wordpress.com/

Also according to Dave Wetzel, (the company who is the sole producer of fermented cod liver oil at this time),

“We do not have a deep focus on the fatty acids in the FCLO because, over time and work, I have concluded that these fatty acids are not what the focal point of the product should be. The only reason EPA/DHA/Omega 3s are discussed/pushed to the degree they are is after one completes the industrialization of these oils they have destroyed/damaged the real deal and they are left with some fatty acids. One always sells what they have. In the case of industrialized fish oils, fatty acids are about all that is left of value.

This is not to say that these fatty acids are not important. These types of oils will always contain a good supply of EPA/DHA and Omega 3s. The real story of Fermented Cod liver Oil is beyond this topic. I think the real story  is the thousands of other molecular structures known and unknown.

In our society the question of EPA/DHA and Omega 3s persist so here is how you can calculate this total for any product if you know the % of EPA/DHA/Omega 3 in any oil.”

That said, I am currently of the opinion that supplementing with an isolated omega 3 polyunsaturated fatty acid is not the best route to improving the omega 3 content of our cells. I have yet to come across a standard fish oil manufacturer who will discuss their production methods from fish to the consumer. What we know about delicate PUFAs is that they are highly oxidizable (susceptible to damage) by the actions of light, heat, and air. We also know that this damage occurs at a much higher rate when the PUFAs are isolated, meaning not within their original, whole-food form. For example, omega 3s in fatty cold water fish are not likely damaged by cooking methods such as poaching or baking, but when oil is extracted from the seed of the canola plant, the remaining delicate PUFA is likely already damaged by the processing it has undergone, and then we are told to cook with this oil. I believe this to be the larger issue around inflammatory PUFAs entering our system than a lack of healthful omega 3s.

Bottom line: When nutrients are readily available in food, we should eat them that way. If omega 3 fatty acids are your main goal of taking a fish oil or even fermented cod liver oil, increasing your fatty cold water fish intake is more likely your best bet.

What if I want to take more DHA than fermented cod liver oil provides?

You may be interested in trying a fermented skate liver oil which is a very rich source of DHA. Skate liver oil contains slightly more EPA/DHA per serving than fermented cod liver oil at 15-16% DHA, 12% EPA.

How much vitamin A and D are in fermented cod liver oil?

vitaminsADinFCLOUnfortunately, the levels in each batch of fermented cod liver oil vary with the batch itself as well as with the testing methods and labs use.

The best estimate that Green Pasture has is roughly 800 IUs of vitamin D per mL, though the company and a lab used to test the vitamin D content has stated that the hard and fast number-value of the vitamin D content may or may not be as indicative of its efficacy as the synergistic value of the vitamin D contained therein. The vitamin D, which is mainly D2 and some D3 in cod liver oil, is not added to the product. It is not standardized and it is not synthetic. It is present in the form of a variety of metabolites, not only one form as in most supplements. Historically, IUs weren’t how people determined dosages, we merely used a bigger or a smaller spoon to take our cod liver oil.

In terms of vitamin A content, the vast majority of the content within fermented cod liver oil is in the form of palmitate and some retinol. Again, without it being an added ingredient, it’s nearly impossible to provide value counts for isolated nutrients within the product for every batch made.

The amount of vitamins A & D in fermented cod liver oil is in a 10:1 ratio balance so that you will be consuming 10x as much vitamin A as vitamin D with each dose – these are natural, healthy, and appropriate levels as they occur in a whole food.


“When someone is looking for numbers, its almost like drug terminology. Cod liver oil isn’t like that. We’re not adding anything to the product.” – Dave Wetzel


“…we have continually pointed out that vitamins A and D work together and that without vitamin D, vitamin A can be ineffective or even toxic. We do not recommend Nordic Naturals regular cod liver oil or any brand of cod liver oil that is low in vitamin D. But it is completely inappropriate to conclude from this 2004 study that cod liver oil is toxic because of its vitamin A content. Similar reviews could be put together showing the benefits of vitamin A and cod liver oil in numerous studies, including the studies from the 1930s. Obviously the solution is to use the type of cod liver oil that people took in the 1930s, which did not have most of the vitamin D removed by modern processing techniques.” – Sally Fallon

What were traditional uses for/benefits of cod liver oil?


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Source: http://archpedi.jamanetwork.com/article.aspx?articleid=1173883

Cod liver oil has been known for decades as a potent immune system supporter as well as for improving heart function, glucose tolerance, vision, and lowering systemic inflammation.

According to Krispin Sullivan,

“Cod liver oil greatly improves heart function to prevent heart disease and to treat it even in advanced stages, after a heart attack and after heart surgery. Cod liver oil alters the linings of the arteries in such a way as to improve healing after damage. This is attributed to the omega-3 fatty acids but vitamin A, D and K all have important roles to play in facilitating mineral absorption, improving muscle function and supporting elasticity of the blood vessels. The inflammation-reducing prostaglandins made from EPA help mediate the inflammatory response in the arteries. In other studies the heart-protective effect was associated with changes in the muscle response to serotonin, increasing the heart’s ability to “relax.” In a study with rats, treatment with cod liver oil actually caused artery-blocking atheromas to become smaller and blood vessel diameter to enlarge.55 Weston Price noted that heart attack deaths increased during periods when the vitamin A content of the diet was low. Cod liver oil can provide vitamin A on a continuous basis throughout the year.”


  • Cod liver oil contributes to bone health, preventing bone and muscle pain and joint pain.
  • Vitamin-rich cod liver oil has been shown to support the health of pregnant women by improving the fatty acid profile of their breast milk to optimize brain health in the infant.
  • Traditionally, infants were given cod liver oil to support immune health until Dr. Spock began to recommend vaccinations  in its place.
  • Vitamin A has long been shown to aid in vision health in diabetics and non-diabetics alike.
  • FCLO promotes proper absorption of calcium and magnesium, thereby helping to normalize blood pressure.
  • Inflammatory conditions like colitis and Crohn’s have been shown to improve with the type of omega 3s in FCLO moreso than to medications often prescribed.
  • Taken orally or applied topically, fermented cod liver oil helps to improve the quality of skin, both on the face and for issues of rashes, diaper rash, wrinkles, and more.
  • The vitamin A in fermented cod liver oil has been shown to be protective against cancer.

source: http://www.westonaprice.org/cod-liver-oil/clo-number-one-superfood

How much fermented cod liver oil should I take?

howmuchFCLOAs recommended by Green Pasture: (Dosage is best discussed with your physician.)

Below are some general ranges you might consider:

Fermented Cod Liver Oil
Children age 3 months to 12 years: 1/8-1/2 tsp
Children over 12 years and adults: 1/2-1 tsp
Pregnant and nursing women: 1-2 tsp

Emulsified oils are made of only 80% cod liver oil, so the dosages are slightly higher.

Fermented Cod Liver Oil & Butter Blend – 2/3 FCLO and 1/3 HVBO
25 pounds or less: 8 drops orally a day
25 pounds: 1/4 tsp a day
35 pounds: 1/3 tsp a day
45 pounds: 1/2 tsp a day
55 pounds: 2/3 tsp a day
Children over 12 and adults: as noted on the bottle [my note, Green Pasture did not provide a dosage recommendation here]

Chris Kresser, L.Ac. recommends a dose of between 5 mL to 10 mL per day for women trying to get pregnant or who are already pregnant or breastfeeding, and a dose of 5 mL per day for men.

Chris Masterjohn states that “An excess of the omega-3 fatty acid EPA from fish and cod liver oil can cause a deficiency in arachidonic acid. For this reason, cod liver oil should be used in moderation and in combination with a diet rich in egg yolks and organ meats.” In other words: more is not better. A standard dose is sufficient for most people.

Should I take FCLO on an empty stomach or with a meal?

It shouldn’t matter much in terms of digestive function whether you take it with a meal or away from a meal as it is a complete superfood, not an isolated supplement. That said, if you do experience any issues when taken away from food, take it after a meal – morning or evening doesn’t matter – just whenever you will remember to take it is the best time to do it.

Is fermented cod liver oil safe for pregnant/nursing mothers, children, and infants?

Yes. Many of the concerns pregnant women have about vitamin A toxicity should be quelled by the fact that FCLO provides vitamin A (and other nutrients) in balance as they occur in the natural, whole food of cod liver. Food-based nutrients are not the same as synthetic, isolated nutrient supplements and often do not carry the same toxicity dangers.

What is a good brand of fermented cod liver oil to purchase?

fcloThe only brand I recommend at this time is Green Pasture.

If I am sensitive to fermented foods, should I take a non-fermented cod liver oil?

I don’t recommend this approach at this time since I have not been able to verify that other ways of processing cod liver oil are safe to my own standards. If you are unable to take fermented cod liver oil due to a histamine or other allergen sensitivity, you may want to increase your intake of fatty cold water fish and fresh liver from pastured animals as well as your intake of vitamin K2-rich foods like grass-fed butter, hard cheeses made from grass-fed milk, and some pastured, clean-ingredient preserved meats like salamis.

Should I be taking FCLO or FCLO/Butter Oil Blend?

If you are looking for the additional value of vitamin K2, then the butter oil blend is likely your best choice. Fermented cod liver oil on its own may have some K2 value, but with the butter oil added, the K2 value is higher. You may also choose to take the FCLO liquid and add butter oil separately to your intake. Butter oil is not the same as eating grass-fed butter or ghee as it is much more concentrated, however, if you feel you eat a very large quantity of grass-fed butter, you may find that you want to only purchase the FCLO on its own. If you have a strong sensitivity or allergy to dairy, you may find you react to the butter oil, though this is far less common than you might imagine since the proteins in the butter are removed to create the butter oil.

Capsules or liquid, which is better to get?

The choices of capsules versus liquid or gel (if you are getting fermented cod liver oil/butter oil blend) depends on your own preferences. The liquid or gel allows for a greater volume of dose per container, so it is a more economical option than capsules. The liquid or gel also allows for a more customized dose size, since you can pour or scoop as much or as little as you like, whereas the capsules limit this a bit. If you find it difficult to digest capsules, the liquid or gel may be your best bet. If you find that it is completely impossible for you to take the liquid or gel, then capsules are a good option to get your dose in. Most parents report that the liquid is easy enough for their kids to take.

How does fermented cod liver oil taste? Is there a flavor that is better than others?

If you get a flavored variety, it tastes mostly like the flavor you selected with a slight background of fishiness. I think the cinnamon flavor is the best and covers up the fishy taste/smell most effectively. Many I know find other flavors palatable, but the cinnamon is my top pick. Standard fish oils are often deodorized and then flavored, making them much more palatable. If you are consuming the oil from the liver of a fish, it should have some hint of fishiness to it!

How can I make my daily dose of fermented cod liver oil easier to take?

Check out Sarah Pope’s video below!


Should I take a fish oil supplement?

Fish oil is very different from fermented cod liver oil. I don’t generally recommend isolated fish oil supplementation for a few reasons.

Fish oil or any other isolated omega-3 fatty acid supplement is geared toward balancing the ratio of n3:n6 (n=omega) in your body. If you’re eating a Standard American Diet, that ratio is likely 1:10 to 1:20. From an ancestral and general health perspective, this ratio should be under 1:4, if possible.

Instead of supplementation, I recommend that you eat fish (a whole food) to get omega-3. Nutrients in food are much more bio-available than supplements. It’s also difficult to know and trust the source of your isolated omega-3 supplements.

Additionally, omega-3 is a polyunsaturated fatty acid (PUFA), and PUFAs are highly susceptible to damage (oxidation from heat, light, and air) if not handled carefully and appropriately. I don’t trust that the delicate polyunsaturated fats in most omega-3 supplements were not damaged in the processing and extraction of the oil. Consuming damaged isolated omega-3 supplements is likely far worse than consuming none at all, so I don’t recommend them.

You may have read about how seed oils are produced in my post about canola oil. In my research on how standard fish oils are produced, I discovered that a very similar process is used and I will cover this topic more in a future post. For now, please take a look at the processing steps and the compounds removed by them that have been summed up in the chart below.

This chart was created by a fish oil industry website to explain the processing – this is not sourced from any organization who wishes to demonize fish oil – it is simply matter-of-fact information about this oil’s production.

Processing steps used to purify marine oils

Carbon Treatment Removal of dioxins, furans, and polyaromatic hydrocarbons (PAH). This can be performed on the starting crude oil if the oil is to be sold into the non-industrial market.
Oil Storage Insoluble impurities, trace moisture and some phospholipids will precipitate out in the tanks. The combination is known as “foots”.
Degumming Phospholipids, sugars, resins, proteinaceous compounds, trace metals and other materials.
Alkali Refining Free fatty acids, pigments, phospholipids, oil insoluble material, water soluble material, trace metals
Water Washing/Silica Treatment Soaps, oxidation products and trace metals
Drying Moisture
Adsorptive Bleaching & Carbon Treatment Pigments, oxidation products, trace metals, sulfur compounds, dioxins, furans, PAH and possibly some pcb’s.
Winterization Higher melting triglycerides, waxes. Used to enhance the unsaturated triglycerides.
Deodorization Free fatty acids, mono-diglycerides, aldehydes, ketones, chlorinated hydrocarbons and pigment decomposition products. This is usually the finishing step and results in a bland tasting oil.
Vacuum Stripping or Thin Film, Molecular or Short Path Distillation Removal of chlorinated hydrocarbons, fatty acids, oxidation products, PCB and free cholesterol. Sometimes this step is used as a replacement for the deodorization step.

source: http://lipidlibrary.aocs.org/processing/marine/index.htm

When it comes to omega-3/omega-6 fatty acid balance, I always recommend reducing omega-6 intake drastically (as you will do when you eliminate vegetable oils, grains, and legumes) before adding any supplementation of omega-3 fatty acids like fish oil. If you’re concerned about systemic inflammation, you may even want to watch your food-based intake of omega- 6-rich items other than oils. Nuts high in omega-6 fatty acids include almonds, pecans, pine nuts, pistachios, and hazelnuts. For the average person, eating foods that contain omega 6 fatty acids naturally is not likely, in my estimation, contributing to excess inflammation the way isolated forms of these fatty acids may be – from seed oils and especially damaged/oxidized seed oils. This is the main problem with restaurant foods and especially fried foods – it’s not the potatoes that make French fries unhealthful, it’s the old, rancid vegetable/canola/corn/soybean oils that they are fried in that make them unhealthful, pro-inflammatory foods.

Chris Masterjohn, Ph. D.

Chris Masterjohn, Ph. D.

According to Chris Masterjohn in his article “Precious Yet Perilous“:

  • The requirement for essential fatty acids is lowest in healthy adults and highest in infants and growing children, pregnant and lactating women, bodybuilders, people recovering from injury, and people with chronic disease. Alcoholism, diabetes, insulin resistance, certain genetic variations, and strict vegetarianism may make someone more likely to become deficient. Additional liver, egg yolks, and cod liver oil can be used to correct deficiencies.

  • Essential fatty acids are vulnerable to a process called oxidation, which can cause cellular damage. Replacing traditional animal fats with polyunsaturated vegetable oils may increase the risk of heart disease, cancer and total mortality.

  • One gram per day of omega-3 fatty acids from fish oil reduces cardiovascular mortality in patients with chronic heart failure or who have recently had a heart attack. However, fish oil may increase cardiovascular and total mortality, especially when used for more than four years in combination with a standard modern diet.


More related FAQs…

What is beauty balm and should I use it?

Beauty balm is a product we refer to often that has been made by Green Pasture and is a blend of oils, including fermented cod liver oil, that is created for topical application. The balm contains a proprietary blend of: Shea Butter, X-FACTOR Gold High Vitamin Butter Oil, Blue Breeze Organic Coconut Oil, Blue Ice Fermented Cod Liver Oil, Cranberry Oil, Organic Orange Oil, Lavender Oil. I highly recommend this product for anyone dealing with very dry skin or simply to apply for nourishment. I have seen great benefits from this balm applied to my face (clearer skin) and hands (softer skin) regularly.

Moller’s processing Fresh cod, steam processing, gentle refining to remove impurities, checked 8x along the way for oxidation and vitamin content (A & D), not added back. The Norwegian Health Authority recommends it be taken daily from as early as 4 weeks of age.


Sources & sites for more information:

Cod Liver Oil Basics & Recommendations (Weston A. Price Foundation – Sally Fallon & Mary Enig)
Separating fact from fiction on cod liver oil (Sally Fallon’s letter on Chris Kresser’s site)
Cod Liver Oil: Nature’s Most Potent Superfood (Chris Kresser)
Talking Nutrient Synergy with Dr. Chris Masterjohn (Episode #69 of the Balanced Bites Podcast)
Cod Liver Oil: The Number One Superfood (Krispin Sullivan – Weston A. Price Foundation website)
Superfood: Cod Liver Oil – Butter Oil Blend! (Liz Wolfe, NTP’s website)
Precious Yet Perilous (Chris Masterjohn)
Vitamin D, cod-liver oil, sunlight, and rickets: a historical perspective. (Pediatrics. 2003 Aug;112(2):e132-5.)
Update on Cod Liver Oil Manufacture (Weston A. Price – Dave Wetzel)
Cod Liver Oil Manufacturing (Weston A Price – Dave Wetzel)
Celebrating Dave Wetzel and fermented cod liver oil (Nourishing Our Children)
Processing of standard cod liver oil (Moller fish oil website)
Purchasing FCLO in the UK – Red 23


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