Industrial Production of Cod Liver Oil: A Fairy Tale

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Fatty acids are classified as saturated, monounsaturated, or polyunsaturated. We can use the story of the three pigs to illustrate how the body uses and stores each type of fat. Each pig went out into the world to build their own home. The first pig built a house of straw, the second pig a house of twigs, and the third pig a house of bricks.

Saturated fats such as coconut oil, palm oil, lard, tallow, and duck fat are the house of bricks. They are highly stable because all of the carbon-atom linkages are filled, or “saturated,” with hydrogen. Saturated fats are excellent for cooking and frying because they remain stable when exposed to high heat. The heavy-duty ‘brick walls’ of saturated fats are the most resistant to breaking down due to heat, light, moisture, and oxygen.

3 pigs corganic

Monounsaturated fats are the house of twigs. Usually coming from seeds or nuts, these fats are liquid at room temperature. Monounsaturated fats have one double bond in the form of two carbon atoms and therefore lack two hydrogen atoms. While some monounsaturated fats can be used for cooking, their smoke point (the temperature at which the oil starts to emit smoke) is not as high as saturated fats. Olive oil, peanut oil, and macadamia nut oil are examples of monounsaturated fats. They are best used for cooking at lower temperatures, sauteing, and in salad dressings. Keep these oils in cool, dark storage places to extend their freshness.

Polyunsaturated fats have two or more pairs of double bonds and therefore lack four or more hydrogen atoms. The unpaired electrons at the double bonds make these oils unstable and highly reactive. They are, of course, the house of straw. Found abundantly in nuts, seeds, and vegetables, as well as fish oils, polyunsaturated oils have a low smoke point. They’re best used as salad oils or for supplementing one’s diet. The highly sought-after omega-3 fatty acids are polyunsaturated fats. In plant oils, such as flaxseed oil, walnut oil, poppy seed oil, and sunflower seed oil, the omega-3s come in the form of alpha-linolenic acid (ALA). In oils such as fish and cod liver oil, they are in the form of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Omega-3 fatty acids are fragile and oxidize (go rancid) quickly. Fresh and unprocessed polyunsaturated fats should be refrigerated and kept away from light, oxygen, moisture, and metal as much as possible. They should also be consumed in a relatively short period of time before the big bad rancidity wolf comes knocking.

A Wolf Dressed in Sheep's Clothing

wolf in sheep

Largely unknown to the public is that commercial cod liver oils go through a battery of processing steps involving high heat, high pressure, vacuums, solvents, moisture, and chemicals. The fragile omega-3 fatty acids are heated so high, in some cases, that trans fats are formed, which remain in the oil. Heavy metals and other contaminants from fish sources in polluted waters, as well as toxins formed due to improper handling, long-term storage, and exposure to heat and oxygen, must be “cleared” from the oil prior to bottling. These highly refined processing steps are designed to create an easy-pouring, shelf-stable cod liver oil. However, the processing steps themselves create additional harmful substances, for which more heat and solvents are required. Each step further weakens the integrity and nutritional value of the oil. Big bad wolves (and even good wolves) use their keen sense of smell to seek out their prey. The human sense of smell is not nearly as sensitive as the wolf’s, but we do use our sense of smell and taste as a preservation instinct, which keeps us from eating rotten and spoiled foods, and even foods that have become rancid. The nose and taste buds give the signal to reject rancid foods before they are ingested or even before they enter the mouth. Industrial cod liver oil processes (similar to vegetable oil processes) eliminate the rancid taste and smell, tricking our senses into believing the oil is fresh and nutritious. Putting fish oil into capsules or adding flavors further disguises undesirable odors and tastes.

industrial production clo


Industrial cod liver oil is sourced and undergoes the following processes:

Sourcing the Fish.

Depending on the producer, commercial cod liver oil could come from actual wild-caught cod, or it could come from pollock or haddock (sourced from Alaska and/or Russia) or other fish species, both wild-caught and farmed. The international production of cod liver oil is regulated by only one rule—the final product must match the specific EPA/DHA ratio found in raw cod liver oil. Cod liver oil contains about 9% EPA and 14% DHA, whereas fish oil generally contains about 18% EPA and 12% DHA. Cheaper oils are often added to achieve the correct EPA/DHA balance. The oil, regardless of the country of origin, is then bottled and sold as true Norwegian or Arctic cod liver oil.

Cod Liver Oil Extraction.

Wild cod are caught in large trawlers that spend weeks at sea. In the best scenario, the fish are eviscerated at sea, and the livers are collected in containers and transported to the rendering plant. At worst, the livers are collected and stored aboard the ship for long periods of time, where they undergo excessive oxidation. Upon arrival at the processing facility, the livers are ground up and then either heated for a length of time or cold pressed mechanically to extract the oil from the livers. The remaining liver mass is then heated and put through a decanter to remove solid parts, before it is centrifuged, separating the liver mass into crude oil, water, and sludge. At this point, the crude oil intended for human consumption is further processed, while the residues are dried to produce liver meal to be sold as fish and animal feed. Most cod liver meal is shipped to Southeast Asia for the shrimp feed industry. The idea that cold pressed cod liver oil is somehow raw or gently processed compared to heat rendering is a marketing ploy. Cold pressing refers to the extraction of the oil from the liver. Once extracted, however, the oil is subjected to high heat during the degumming (212° F), deodorization (374° F or higher), and molecular distillation (392° F) steps.

Carbon Treatments.

Carbon treatments are used on the initial crude oil to remove dioxins, furans, and polyaromatic hydrocarbons (PAH), which are toxic. The European Union recommends the reduction of dioxins, furans, and PCBs in feed and food. It sets out action levels for certain food sources, including farmed fish, to encourage member states to proactively reduce dioxin levels. When these contaminants occur in wild-caught fish, the reason is environmental pollution rather than a point source; therefore, no action levels have been set for wild-caught fish. Generally, carbon treatment is necessary for farmed fish and fish caught near industrial areas.


The crude oil is hydrated, heated to 100° C (212° F), and treated with phosphoric acid to separate the phospholipids, resins, proteins, minerals, and other materials intrinsic to cod liver oil. The main reason for the removal of phospholipids is that some of the compounds, particularly the calcium and magnesium salt of phosphatidic and lysophatidic acids, are strong emulsifiers. If these compounds remain in the oil during the alkali refining/neutralization step, they may inhibit the separation of the soaps. Phospholipids (also called phosphotides) will react with water to form insoluble sediments.

Alkali Refining or Neutralization.

Due to the length of time between harvesting the fish and sitting in holding tanks, the oil’s triglycerides break down, through hydrolytic rancidity, into free fatty acids, creating a rancid smell/taste, and the oil begins to turn brown. To remove free fatty acids, pigments, phospholipids, and water-soluble materials, it is necessary to alkali refine the oil. This process produces soaps that must be removed with water or steam washing, followed by centrifuging.

Water Washing.

Water washing and silica treatment remove the soaps created by the alkali, oxidation products, and other trace metals.


Drying removes the moisture from the water washing. Moisture, heat, oxygen, light, and reactive metals further contribute to the oil’s rancidity.


The major objective of bleaching is to return the oil to an acceptable pale color using clays treated with mineral acids. Depending on how long the oil has been sitting, up to 2% bleaching earth may be used. Acid-activated bleaching earth also cleans out the hydroperoxides in the oil formed during previous steps.


Winterization concentrates the omega fatty acids. This is addition by subtraction. The oil is cooled to sub-zero temperature, causing crystallization and reduction in the amount of saturated fatty acids. Triglycerides and waxes are also removed. Removing the saturated fats and triglycerides further destabilizes the oil, as the remaining polyunsaturated fats, in the form of omega-3 fatty acids, are very fragile and oxidize easily. The human body does not require concentrated levels of essential fatty acids, especially in an isolated form. Denaturing the oil creates an imbalance that severely weakens its effectiveness.


To remove additional free fatty acids, mono- and di-glycerides, hydroperoxides, aldehydes, ketones, chlorinated hydrocarbons, volatile compounds (rancid fishy smells and taste), and pigments formed during the previous processing steps, deodorization is necessary. During this process, the oil can be heated up to 190° C (374° F) or higher as live steam passes through the oil at low pressure. This step may lead to the formation of trans fats (trans isomers) of EPA and DHA. A study on fish oil capsules on the European market found that all products studied had levels of trans fats. Trans fats were found in up to 4.5% of the total EPA and up to 5.9% of the DHA. This step also damages or destroys most of the vitamin A and vitamin D naturally found in cod liver oil.

Molecular Distillation.

Molecular distillation removes most of the remaining pesticides and organic pollutants, which include dioxins, lindane, DDT, as well as bromated compounds (flame retardants) and reduces all such environmental pollutants to lower levels. Temperatures can reach 200° C (392° F). Sometimes this step is used as a replacement for deodorization. Molecular distillation is also responsible for a tremendous loss of vitamins A and D naturally occurring in cod liver oil and the creation of trans fats due to high heat.

Synthetic Vitamins.

Almost all of the natural vitamin A (retinol) and vitamin D3 (cholecalciferol) is removed during the industrial processing of cod liver oil. At this stage, the majority of cod liver oil producers add vitamin A from a synthetic source, retinyl palmitate. Synthetic vitamin D3 derived from lanolin in sheep wool as a cholesterol source is purified to form 7-dehyrocholesterol, irradiated to form D3, and added to the highly processed cod liver oil. Sheep's wool is not a natural component of cod liver oil. Synthetics may also contain additives, colorings, fillers, byproducts, and other chemicals not found in the natural versions and are produced with the aid of harsh chemical reagents. Many animal studies have shown differences in absorption of synthetic compared to natural vitamins. Synthetic vitamins do not perform the same functions in your body as vitamins found naturally in whole food, which are very complex and work with other nutrients to produce their specific biological effects. Many synthetic vitamins deplete your body of other nutrients, and the kidneys must work harder to excrete them through your urine.


Once the oil is cooled, antioxidants are always added to processed fish oil for human consumption to protect the oil from further oxidation. “Natural” forms of antioxidants, such as ascorbic acid, isolated vitamin E tocopherols from soy, citric acid from GMO corn, and spice extracts are often used. The most common synthetic antioxidants are BHA (butylated hydroxyanisole), BHT (butylated hydroxytoluene), TBHQ (tert-butylhydroquinone), and propyl gallate.


To cover up the rancid fishy taste, most commercial cod liver oil producers will add flavorings such as “natural lemon flavor” to their products. While the flavor may be naturally derived from the peel of the lemon, the actual contents are proprietary, and the flavoring companies do not have to divulge their processes or ingredients (only certify that the flavoring is free of the eight major allergens). The flavorings are not organic, and some customers may have a reaction to the flavoring because of the citrus content. Other producers will use synthetic citrus flavorings and fruit flavorings derived from a mix of proprietary chemicals.



Fresh Cod Liver Oil is Now Available

Manufacturers of commercial cod liver oil would have you believe that some or all of these processes improve the nutritional value and cleanliness of the cod liver oil. The truth is that these processes are destructive to the oil. Cod liver oil is recommended and taken for the beneficial levels of vitamin A, vitamin D3, and omega-3 fatty acids naturally contained in wild-caught cod. As outlined above, the refining process severely damages these nutrients. The addition of synthetic vitamins in cod liver oil creates a product that is essentially no better than taking synthetic vitamin pills, which won’t include the fishy aftertaste. Most of the fragile omega-3s are broken down into free fatty acids and removed, along with a percentage of the remaining EPA and DHA containing trans fats. While these processes may be profitable for the cod liver oil producers and relatively inexpensive for consumers, the end result is a sterile oil with little to no healing effects that is likely to add oxidative stress to the body.

Click here to learn more about the production of Rosita Extra-Virgin Cod Liver Oil

Rosita method

Rosita Real Foods, based in Northern Norway, takes an old-world (paleo) approach to creating their Extra Virgin Cod Liver Oil (EVCLO). The Rosita family uses their own small fishing boats to fish the pristine waters of northern Norway, just as their Viking ancestors did. Only wild-caught Atlantic cod (Gadus morhua) are harvested, and the livers are individually inspected for health and plumpness. The extraction of EVCLO requires no heat, chemicals, solvents, putrefaction, or pressure. The raw oil then passes through seven layers of paper filters (similar to coffee filters) to remove any remaining fish sediment, followed by a proprietary sponge-like process that removes contaminants without the use of heat or solvents. A tiny drop of natural antioxidants (organic rosemary herb and organic vitamin E) is added to each bottle to extend the freshness of the fragile polyunsaturated omega fats. The process, from fishing to bottling, is completed within 48 hours. EVCLO is the first and only raw and fresh cod liver oil on the market. No other cod liver oil or food found anywhere in the world contains the high levels of vitamin D3, vitamin A, and omega-3 EPA and DHA in their natural state and proper ratios. No flavors are added to fresh EVCLO, and no processes are used to disguise the taste.

Click here to buy Rosita Extra-Virgin Cod Liver Oil


  • O’Connor A. What’s in Your Fish Oil Supplements? New York Times. 12 Jan 2014
  • Bimbo, A. The Production and Processing of Marine Oils. The AOCS Lipid Library.
  • Hjaltason B. and Garaldsson GG. Fish Oils and Lipids from Marine Sources. In
  • Modifying Lipids for Use in Food. F.D. Gunstone, edit. CRC Press: Boca Raton FL 2006. 64.
  • Ibid, p 74
  • Rajakumar K. Vitamin D, cod-liver oil, sunlight, and rickets: a historical perspective. Pediatrics. 2003 Aug; 112(2):e132-5;  Hjaltason B. and Garaldsson G.G., 56
  • Editorial. Oilless Cod Liver Oil. JAMA 20 Feb 1915; 64(8) 667-8
  • Ottoboni A. Ottoboni F.  The Modern Nutritional Diseases. 2013. NV: Vincente Books; Hjaltason B. and Garaldsson G.G., 57.
  • Mercola J. Important Cod Liver Oil Update. 23 Dec 2008.;;  Cannell J. Newsletter: Vitamin A Toxicity. Vitamin D Council. 15 Dec 2008
  • Sciotto C. Mjos SA. Trans Isomers of EPA and DHA in Omega-3 Products on the European Market. Lipids. 47: 650-667/
  • Hjaltason B. and Garaldsson G.G. 68.
  • Ibid. 64-68.
  • Ibid. 68-70.
  • Ibid. 70
  • Ibid 68-69
  • Albert BB et al. Fish oil supplements in New Zealand are highly oxidized and do not meet label content of n-3 PUFA. Scientific Reports 5(7928).  21 Jan 2015
  • Fresh or rotten?  Rotten fish oil polluting the market and putting health at risk.
  • Rubin Report.   Lite oksiderte omega-3 oljer og potensielle helsefordeler. NOFIMA 196:4647  October 2010,


Disclaimer: Please consult with your physician before using Rosita EVCLO, or taking this product if you are pregnant or lactating, diabetic, allergic to fish or iodine, using blood thinners, anticipate surgery, have a diagnosed cardiovascular condition, nutrient absorption issues, dealing with a chronic disease, bleeding or immune system disorders. Keep out of reach of children.

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

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