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Cod (or other fish) liver oil (CLO) for omega-3 EPA / DHA

It's all in the details . . .

If you choose cod liver oil as your daily Omega-3 supplement, it should be a quality, low- or no-heat processed undamaged) oil, containing its naturally present  A and D vitamins.   Quality CLO takes center-stage for its high content of these very necessary antioxidant vitamins, which are deficient in many people.   Vitamin D ‘s presence in the body is particularly low in those living in sunless climates, but also those in sunny areas, where many foolishly avoid the sun completely – either to avoid skin cancer or because their lives keep them indoors too much.

Vit A:• Absorbs minerals
• Builds muscle
• Immune system
• Aids good eyesight
Vit D:• Needed for strong bones
• Precursor to sex hormones
• Used by virtually every body cell

–    Fish and animal livers contain the highest level of vitamin A.     Since most people choose not to eat animal liver on a daily basis, then taking a daily supplement of a fish liver oil is one other way to ensure critical vitamin A;

–   Deep-water cod get their vitamin D content by indirectly eating phytoplankton which absorb sunlight in surface waters.    Phytoplankton is a tiny, plant-like organism drifting freely on the water’s surface, which utilizes nutrients from the water and captures energy from the sun by photosynthesis. Rich in EPA /DHA,phytoplankton is eaten by zooplankton, which is eaten by other fish, which are themselves eaten by cod.

CLO contains about the same amount of EPA /DHA,as natural fish body oil and krill oil but less than the newer concentrated oils).

Criteria for a good cod (or other fish) liver oil

A cod liver oil supplement ideally needs to be:

 Minimally processed.   To retain the integrity of the easily damaged omega-3 fatty acids and to prevent lipid peroxidation:

•   Processed in the absence of light, air or heat below 320°(temp. at which trans fats begin to form). 

•   Not destearinated or processed using solvents or bleach

•   Not molecularly distilled.  Some sources of cod liver oil use this method to remove contaminates, others use a filtration system.

Free of toxins (such as pcbs, mercury, dioxins) and lipid peroxides (oxidized fatty acids capable of producing damaging free radicals), and independently tested to verify purity;

High in NATURAL Vitamin A and D.   These vitamins are necessary to be able to absorb minerals; Since natural vitamins A and D are so critical to health, and are not easily obtainable in the diet, it makes sense to choose a marine oil supplement containing both quality EPA /DHA and high-level vitamins A and D. Most brands of cod liver oil go through a process that removes all of the natural vitamins, including A and D.  Some companies add synthetic  and D back in

Contain sufficient Omega-3 EPA and DHA to ensure a daily dose of a total of about 1000 mg EPA and DHA in a reasonably-sized daily dose.    In addition to the fish liver oils, eat oily fish such as sardines, herring, mackerel, anchovies, menhaden and wild salmon, which contain high EPA /DHA

Able to pass a taste test!    Otherwise you may be deterred from taking the oil on a daily basis.   Capsules are available, but usually require taking a lot for an equivalent liquid dose;

Fresh fish or cod liver oil does not have much of a taste or smell. The horrible tasting cod liver oil you may remember taking in the past, was most likely rancid;

Note: EPA / DHA and Vitamin A and D amounts vary with season and test methodology used;

Recommended brands of cod liver oil

Green Pasture® fermented cod liver oil (FCLO)


Cost (2/2024):

•   Liquid: $36 / bottle (amazon).    75 days – 1/2 tsp. per day (? mg EPA  / ? mg DHA). Cost / month: ~$14.40

Also sold by Radiant Life.

FCLO is processed without heat.     It is produced using a technically controlled process, based on the traditional method of allowing cod livers to sit in a barrel in the sun until the oil naturally separates and floats to the top. Green Pastures® uses a proprietary natural lacto-fermentation and cleaning method, that DOES NOT USE HEAT, to produce a toxin-free, undamaged oil. The age-old fermentation process is considered to increase the oil’s nutrient concentration and bio-availability. The oil contains around 400 IU / tsp vitamin K2, which protects heart and brain function and moves calcium to where it should be in the body – out of the arteries and into the bones. 1 teaspoon of FCLO contains 9500 IU vitamin A and 1950 IU vitamin D, a ratio of about 5:1. 

Unfortunately, a 2015 report personally funded by Kaayla Daniel, phD (a former member of the board at Weston A. Price Foundation (WAPF)), casts a shadow on FCLO.  Her 110 page report “Hook, Line and Stinker: The truth about fermented cod liver oil” available here,  included lab results that mentioned several problems, of which 3 are of particular concern to this author:

(1) Some reported lab results indicated rancidity in some of the  FCLO she had tested.  This was partly based on free fatty acid content, which may not be a valid measure of rancidity. Other indicators of rancidity were mixed. If oil’s EPA / DHA has been oxidized, it is no longer present in the oil – – – The EPA / DHA content of FCLO was measured at around 1000mg (315 mg DHA + 685 mg EPA) / tsp., which is 20% less than Rosita’s extra virgin cod liver oil at 1200 mg.

Of relevance, is a study comparing unrefined, fermented (Green Pastures is the only producer) and molecularly distilled CLOs, that found that MDA, an indicator of polyunsaturated fatty acid oxidation, was 10-fold higher in the fermented product, . . .”Brandon et al, 2012  This is very concerning, since PUFA oxidation is linked to several serious health problems, as written about by Dr. Mary Enig of WAPF.  MDA can damage proteins, DNA, and other important cellular structures.

(2) Dr. Daniel states that due to the low carbohydrate content of cod liver oil, that it can not be fermented.

In a blog at green pastures website, Dr. Sathivel, a Professor of Food Engineer, analyzes some reports of analyses for FCLO done in Sep. 2015 by two independent laboratories, mentioning that average MDA value of the oils tested was below the acceptable level, and concluding that FCLO is a good oil. However, there is no mention of the source of the FCLO analyzed. 

Q and A rebuttal by Weston A. Price Foundation in 2015 allays concerns in Dr. Daniel’s report

Green Pastures Blue Ice CLO

Rosita extra virgin cod liver oil (EVCLO)


Natural cod liver processed without heat, chemicals or mechanical pressure.

Contains natural vitamin A and D.

Oil smells and tastes fresh.   Fish caught off the coast of Norway. Every batch tested to meet strict European regulations. independent lab results

•   EPA/DHA    1/2 teaspoon (2.5ml, 2.3 grams) contains ~220 mg EPA  / ~300 mg DHA

•   Vitamin A .  1/2 tsp. contains ~2000 IU

•   Vitamin D.   1/2 tsp. contains ~200 IU

Cost (2/2024): 

•   Liquid: $65 / bottle (amazon).    60 days – 1/2 tsp. per day (~143 mg EPA  / ~195 mg DHA). Cost / month: ~$32.50

•   Capsules: $65 / 90 capsules (amazon);    3 capsules per day (~143 mg EPA / ~195 mg DHA) Cost/ month:$ 65  Twice as much as liquid   

Nutrapro cod liver oil

Concentrated oil has higher EPA / DHA than unconcentrated oils

Cost (2/2024):

•   Liquid: $33 / bottle (amazon).    95 days – 1/2 tsp. per day (~250 mg EPA  / ~360 mg DHA). Cost / month: ~$4.54

NutraPro International virgin cod liver oil nutraprointl.com

How to supplement CLO

Recommended CLO dosages

Adults / Children over 12 years: 1/2-1 teaspoon / day. You should not take more than 1 tablespoon CLO per day

Children 3 months – 12 years:  Half the adult dose

Pregnant and nursing women: Double the adult dose

No need to refrigerate CLO

Your diet should include sources of vitamin K2 along with cod liver oil

The best sources of vitamin are fermented foods and grass-fed animal fats. E.g. good quality butter, ghee, high-vitamin butter oil, or cheese (especially Brie, Gouda, Edam, Jarlsberg) and duck or goose liver. Dr. Price, the namesake of WAPF,  found that vitamins A and D work synergistically with what he called “Activator X” in high vitamin butter oil, which after a 60 year search is now recognized as vitamin K2  

Consume only fresh oil and keep it in the fridge  (consuming a rancid oil will do more harm than good).   The oxidation culprits are light, heat and air, especially light. Oil should have been bottled with a nitrogen-flush process to remove air (protects unopened oil from oxidation) and in a dark glass bottle. . Once opened, air will begin to oxidize the fatty acids, so do not use oil that has been opened for over a month.  Oil from an newly opened bottle can be transferred to smaller bottles and filled to the top, to be reopened as needed.    T

Vitamin A and D content of fermented high-vitamin CLO

Vitamin A

Fermented high-vitamin CLO contains about 1900 IU vitamin A /ml.  i.e.  1/2 teaspoon of high-vitamin CLO contains about 4750 I.U. of vitamin A

The daily requirement for vitamin A is around 5,000 IU (child), 10,000 IU (> 12 yrs), 20,000 IU (pregnant) /day.   Weston Price points out that these doses are much higher that the U.S. RDA, but necessary because of the now recognized widespread deficiency of  vitamin D

Vitamin D

Fermented high-vitamin CLO contains 390 IU /mL vitamin D /ml.  i.e. 1/2 teaspoon of high-vitamin CLO contains about 975 I.U. of vitamin D.

The MINIMAL daily requirement of Vitamin D should be ~ 4,000 I.U. from all sources.   Rather than the woefully deficient suggested RDA of 200-400 I.U.Ideally we should be going out in the sun, but depending on the brand we use, the vitamin D in cod liver oil at least supplies some of our DVitamin D also protects the oil from oxidation.

Capsules vs. Liquid


•  Much less expensive than capsules

•  The best way to take CLO is to stir it into a small amount of water or fruit juice


For those who can’t handle the taste of liquid oil.

•  Protect oil from oxygen;

•  Protect user from its taste!

• To get a useful dose requires taking several capsules

• Capsules are 3-4 times the cost of liquid for equivalent dose

Other cod liver oil choices to consider

Available in the U.S. recommended as “good” by WAPF:

Engelvaer Cod Liver Oil 

Garden of Life Olde World Icelandic Cod Liver Oil 

NOW Foods double strength Cod Liver Oil capsules

Pharmax Cod Liver Oil

Sonne’s Cod Liver Oil

Swanson double strength Cod Liver Oil capsules

Twin Labs non-emulsified liquid Cod Liver Oil


Brandon T. Metzger, David M. Barnes (2012) Nutritional profiling of cod liver oil processed by molecular distillation, fermentation, or unrefined. The FASEB Journal 2012 26:1_supplement, 636.1-636.1. Abstract

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Deeply concerned about seeing so many people experiencing way too many health issues and weight challenges, I set out on a 20+ year journey to find out what was going wrong and what could be done about it...


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Food Fats and Oils – Healthy or Not?
Meet the Fatty Acid Families
Fat’s digestive journey
Cholesterol – Our Hero
Cholesterol and Saturated fat are NOT the “Darth Vader” of ischaemic heart disease
Food Oils
Best Frying Fats
Expeller-pressed vs, Solvent extracted?
Animal fat
Avocado oil
Canola oil
Coconut oil
Olive oil
Palm oil
Peanut oil
Selecting / Storing oils
Essential Fatty Acids
EFAs – Fats of Life!
Damaged / Toxic Fats
Health issues help w/ anti-inflammatory EFA supplementation
EFA Deficiency Symptoms
“Omega-3 Fix”
“Omega-3 Fix” – Omega-3 +++
We need more omega-3
How to do the “Omega-3 Fix”
EFA amounts in foods
Flax seed – 0mega-3-rich Oil, Lignans, Fiber
– Flax seed baking and storage stability
Eating fish for omega-3
– Are fish too toxic to eat?
– Salmon choices
How to choose a good marine oil supplement
– Fish oil
– Cod liver oil
– Krill oil
– Typical processing for marine oils
Science behind the “Omega-3 Fix”
Can we convert plant Omega-3 ALA to the needed EPA / DHA ?
“Omega-3 Fix” Recipes
Oats ‘n’ Flax Porridge
Fruit Slushy
Creamy Nuts ‘n’ berries
Budwig Salad Dressing
Budwig Spread
“Omega-6 – “How-to”
How to obtain good omega-6 fats
Borage, Blackcurrant or Evening Primrose Oils for Omega-6 GLA
EFAs – 5 vital functions:
(1) Cell Membrane integrity
(2) Cellular energy production
(3) Eicosanoids-“First Responders”
• EFA Conversion Chart
• Specific Eicosanoid Effects
(4) Systems Support
(5) Child Development