Constant Controversy

Cod Liver Oil and Our Changing Food Paradigms

Cod liver oil—what is it? That stinky stuff kids had to take on a spoon? A magic medicine that heals rheumatism, clears the scrofula of TB and helps children recover from measles? A beauty aid that smooths the skin? A messy industrial product used to tan shoe leather? A clean, clear, standardized yellow liquid or a brown oil that rises from rotting livers?

It’s all of these and more. In fact, our views on cod liver oil can serve as a kind of bellwether for evolving attitudes on food, health and processing over the years. Cod liver oil is the quintessential traditional “natural” remedy and also one of the first common foods subjected to industrial processing. And as tradition has collided with modern science, cod liver oil has suffered the buffets of changing attitudes. Even in the early days, when this ancient folk remedy first caught the attention of modern physicians, it provoked instant and constant controversy.

Since early human settlement in northern Norway, cod and cod products have served as the cornerstone of industry for the region. Even as early as the Viking Age, cod liver oil brought prosperity as a chief item of trade with northern Europe, both for consumption and for industrial purposes. Some types were used for oil lamps, ovens, leather treatment, paint manufacture, coloring processes in textile production, soap manufacture, tempering and lathing of steel, manufacture of explosives for the armaments industry, and industrial lubricants, while more carefully extracted versions were consumed as a food and medicine for humans and animals, or used as skin creams and healing ointments, and even as a lubricant for childbirth.1

The method used by the Vikings was actually a kind of steam extraction. They brought water in a pan to boil and then placed birch tree branches on top of the pan; the cod livers were put on top of the branches. As the steam from the boiling water rose, it began to cook the livers, and oil from the livers would drop into the pan.2

The first notes on cod liver oil used for medicinal purposes appeared in 1789 in Manchester, when a Dr. Darbey described using cod liver oil as a remedy for rheumatism. In 1824, a German journal mentioned cod liver oil as a remedy for rickets.3

The year 1841 saw the publication of the Treatise on the Oleum Jecoris Aselli or Cod Liver Oil as a Therapeutic Agent in Certain Forms of Gout, Rheumatism, and Scrofula; with Cases, by John Hughes Bennett, MD. (Scrofula, by the way, is tuberculosis of the neck, characterized by firm, rubbery nodes that eventually break open and supperate. It was a common medical problem at the time.) Bennett was “formerly president of the Parisian Medical Society, and of the Royal Medical and Royal Physical Societies of Edinburgh.”

Bennett notes that cod liver oil had a long history as a popular remedy in Sweden, Norway, Germany, Holland, Scotland, Britain, France and Belgium. He describes it as useful in treating gout, rheumatism, scrofula, caries, diseased joints, tubercular affections, enlarged mesenteric glands (a type of lymph node) and obstinate chronic afflictions of the skin.

In the early days, according to an industry document, fishermen put the livers in barrels to ferment, bringing them into port when the fishing was over. As the weather grew warmer, the cod liver oil separated from the livers and floated to the top. “This type of oil is called ‘raw cod liver oil’ and was drawn off continuously. The first cod liver oil to be separated in this way is clear with a mild taste and is referred to as ‘raw medicinal oil.’ Subsequently, the liver emits a darker and stronger tasting cod liver oil.” Thus, according to this document, both a pale and a darker oil came off the fermenting livers.

Fall2015-fallon-bottleBottle of Whitman’s emulsified cod liver oil, produced in Boston, circa 1910. The color of the oil is brown.

When no further oil could be extracted in this way, the remains were heated in iron cauldrons. This oil was called “brown oil” and was considered the poorest quality—and presumably sold for industrial uses.4

In his 1841 publication, Bennett begins by describing a light or yellow transparent cod liver oil and one that is brown and opaque. The lighter one is generally used in medicine, he states, while the other is used for industrial purposes, such as the preparation of leather. However, on questioning physicians, he found that many stated a preference for a darker oil. This darker oil, he says, is not the same as the industrial oil, but something between the clear yellow oil and the dark, opaque, unpleasant-smelling industrial oil. This oil is described as brown or reddish but translucent.

“Many apothecaries in the large towns of Germany have told me that they only keep two kinds, which they call the white and the brown, and that the latter only is used medicinally; but this, in point of fact, is the yellow variety. At Wildbad, however, being present at the half-yearly medical association of Wurtemberg, I had an opportunity of examining and comparing the three different kinds of cod liver oil, then presented to the meeting [September, 1840]. The first was of a light straw colour, almost white much resembling, in appearance, castor oil, perfectly transparent and of a peculiar taste. . . The second was of a golden colour, also transparent, but somewhat less disagreeable to the smell and taste; and the third was of a deep chestnut brown colour, almost opaque, exceedingly nauseous to the taste, and produced an impression on the tongue which gave rise to a burning sensation. Of these the second or deep golden yellow colour is for the most part used medicinally throughout Germany, although, in different places, it is more or less turbid and deep in colour. By some, however, the third or brown kind, not withstanding its disgusting taste, is preferred. When in Mayence last March, I was furnished by Mr. G. Von Siebold, an apothecary of that town, with a cod liver oil, which he said had been prepared for medical purposes with great care. It was clear and transparent, and of a dark reddish colour when held to the light, resembling the colour of diluted tincture of iodine. The taste of this oil is not more disagreeable than the yellow variety, but not having hitherto been much used in medicine, its therapeutic virtues are unknown.”

Thus the four types of cod liver oil then available can be summarized as:

• Very light or white: Not preferred by physicians; unpleasant taste and odor (probably bleached with chlorine);
• Yellow, clear, most often preferred by physicians, less disagreeable odor and taste. Sometimes described as “brown”;
• Reddish brown, clear, smell and taste like the yellow, prepared for medical purposes, considered the best by many physicians;
• Dark brown oil, opaque, disagreeable smell and odor, leaves a burning sensation on the tongue; probably sold for industrial uses but nevertheless used by some physicians.

In a footnote, Bennett notes that he found a cod liver oil very similar to the reddish translucent oil he had found in Mayence in London, Edinburgh and parts of Germany. The London cod liver oil came from Newfoundland. The cod liver oil from Hamburg or Bremen is “that kind which has been employed with such good effect throughout Germany, and which, in colour, resembles old Malaga wine.”

Bennett encountered many descriptions about how cod liver oil was processed. One source told him that the livers were placed in casks and “allowed to putrefy, by which means the oil is separated.” By another method, used in Bergen, Norway, the light variety percolates “itself from the liver of the fish, but that the brown kind is obtained by boiling the residuum, when no more of the former will flow out.” Another physician relates that three kinds are prepared in Bergen, “one by spontaneous percolation, a second by pressure, and a third by coction” [boiling]. Another source states that “the light oil flows from the liver during the first few days, merely by the action of the sun’s heat, and the brown oil is procured afterwards from a period of eight to fourteen days, when it has become putrid.” Yet another source states that “. . . both sorts are obtained by the artificial application of heat; the lighter is the first portion, which is procured and skimmed off, and that the brown is procured by a stronger heat, which induces a certain degree of decomposition.” Yet another source “asserts that the lighter oil is obtained by boiling the liver, and the brown by boiling also the intestines which are surrounded with fat.”

Another method involves placing the livers in an upright cask with three spigots, one above the other. Upon exposure to the sun, the fat melts. The clearest oil flows from the upper spigot while the other two yield two kinds of brown oil. The residue left in the cask, subjected to hot pressure, “yields a very dark and thicker oil, which is for the most part used in the preparation of leather.”

Preparation of cod liver oil on the coast of Ireland proceeds by heating the livers in an iron pot “until their substance is broken down.” The oily pulp is put into a canvas bag and drained with pressure. A second heating and pressing of the residue yields an oil that is more dark colored and more strongly scented.

In some areas, the fishermen simply boil the livers in an iron pot and then filter the oil through a towel containing a little sand.

A source from Sweden described processing that rendered the four kinds of oil Bennett had found in some apothecary shops:

• “(a) The first, which is almost of a gold yellow colour, much resembling old Rhine wine, quite clear and clean, and with a peculiar strong fishy smell, is obtained by the heat of the sun acting on the liver, placed in large cylindrical glasses. The oil then comes away, leaving the other fatty matters as a residuum. This kind is the most active, but as it cannot be obtained, in comparison with the other kinds, in so great a quantity, is seldom found in commerce, and is very dear [expensive].
• “(b) When from the liver, treated as above described, no more oil can be obtained, the residuum is placed in vessels made expressly for that purpose (or, in some laboratories, on tinned copper plates), and is exposed to 40o Reaumur [122o F], whereby a considerable quantity of oil flows out, which is darker and not so clear as the former, but has still a strong fishy smell, and in colour is between that of Madeira and Malaga wines. This kind is little inferior to the other, and in Sweden, is equally used internally as a remedy.
• “(c) When no more oil can be obtained from the liver in this manner, the residuum is placed in a kettle, cut in pieces, and then roasted, whereby the third kind, or the less pure. . . oil, is procured. It is thicker than the former kinds, not clear, it resembles in colour common syrup, but is somewhat browner, and possesses a strong, penetrating and burning fish taste and smell. This sort, which not only contains the oily and fatty, but also the biliary ingredient of the fish’s liver, is never used as a remedy in Sweden, but is employed in the preparation of leather, and hence is sold in immense quantities under the name of Curry oil.
• “(d) Besides these, there is prepared by chemical means a fourth kind [probably bleaching by chlorine], which is quite clear, has a very weak fishy smell, is similar in appearance to olive oil, and is disposed of in commerce as the only pure oil, but is never used internally in Sweden, and is there considered inert.”

Thus in Sweden, as in the rest of Europe, physicians recommended both the yellow and the clear brown cod liver oil, generally avoiding the thicker opaque brown oil as well as the very light oil.

A modern book on fish oils confirms the fact that before industrial processing, the medicinal oils were obtained by fermentation: “Formerly, the livers were allowed to stand in wooden vats or barrels, and the oil was removed as it floated to the surface after being released by autolysis [fermentation]. The two first batches removed in this fashion were used as medicinal oil, and the remainder as industrial oil. The residue was heated in underfired iron kettles, giving a dark oil which contained large amounts of free fatty acids.”5

Several years later, in 1849, L.J. de Jongh, M.D. of the Hague published a booklet entitled The Three Kinds of Cod Liver Oil; comparatively considered with reference to their chemical and therapeutic properties. He delineates three types of oil: a dark brown oil with a disagreeable smell and bitter taste; a dark oil, the color of Malaga sherry, with a smell not disagreeable and a fishy, bitterish taste; and a gold-yellow oil with a smell not disagreeable and a fishy, bitterish taste. He noted that opinions vary as to which type is the best, but de Jongh himself preferred the brown or light brown varieties (noting that sometimes the pale oil had been “blanched by chlorine.”). He based this opinion on his own clinical experience using all three types. “The brown cod liver oil has proved itself a most powerful remedy in rheumatism and scrofula.”

A few years later, in 1855, de Jongh wrote a two-hundred-ten page book: Cod Liver Oil. Causes of its Frequent Inefficacy and Means of Removing the Same; with Remarks upon the Superiority of the Light Brown over the Pale Oil, Directions for its Use and Cases in which the Oil has been used with the Greatest Effect. By that time, he was marketing his product, Dr. de Jongh’s Light Brown Cod Liver Oil, throughout Europe and importing it to the United States. Based on his clinical experience, he concluded that both pale and light brown cod liver oil were effective in curing a variety of diseases, including tuberculosis, but that the brown oil brought a resolution of the symptoms in half the time compared to the pale oil. The “causes of its frequent inefficacy” seem to be the giving too much, or giving cod liver oil without also prescribing a diet of nutritious food. De Jongh also noted that cod liver oil rarely cured advanced cases of tuberculosis but generally prolonged the life of the patient. He found it very effective for reproductive disorders.

Even from the early days, disagreements abounded not only as to the best color, but also as to whether cod liver oil was even safe to consume. Bennett warned that prolonged use could sometimes result in digestive disorders. The doses he recommended seem huge: one to two tablespoons two to four times daily for adults and one to two teaspoons two or three times daily for children of twelve months and under. “To obtain any benefit,” he says, “a genuine yellow or brown oil must be employed.”

As an aside, Bennett praises animal fat, noting that “butchers, oil men, tallow chandlers, tanners and other individuals who are continually coming in contact with fatty matter, are particularly robust and well-nourished, and are known to be remarkably free from scrofula.” Bennett shows great prescience in claiming that “a fat animal diet supports the action of the oil.” We now know that the omega-3 fatty acids in cod liver oil require balance with the omega-6 arachidonic acid from animal fats; and that saturated fats in general protect against any harmful tendencies of polyunsaturated fish liver oils. Bennett also warns: “All substances abounding in starch are to be avoided.”

Remember that these discussions occurred before anyone knew what a vitamin was. Bennett felt that the best cod liver oils were those that provided iodine and phosphorus.

His conclusion: “The best is the clear brown or reddish variety, next in power is the yellow, and the least beneficial is the white. A sample of the oil employed should always be analysed in order to determine whether it contains iodine as a constituent. . . .”

The first industrial cod liver oil production method was steam extraction—a method that is still used today. Typical of the reputation that science and technology enjoyed, as the bringer of cleanliness and purity to replace traditional, less-than-sanitary processing, is this description from A Thousand Years of Norwegian Oil: Lofoten as Global Manufacturer of Cod Liver Oil: “Prior to 1850 all cod liver oil was manufactured in the old way, by allowing fermentation and putrefaction, or by boiling the liver. The quality of this oil was abysmal. A major technological breakthrough occurred in 1854 with Norwegian pharmacist Peter Moller and the commencement of the manufacture of cod liver oil in Lofoten [the northern coast line of Norway]. Because of this, it became possible to manufacture high quality medicinal cod liver oil at a lower cost.” (The same document notes that homemade cod liver oil, accused of “abysmal” quality, “always” kept the fishermen healthy, in spite of the wind, rain, cold and snow they endured to practice their profession.)6



The Three Kinds of Cod Liver Oil; comparatively considered with reference to their chemical and therapeutic properties, by Dr. De Jongh.


Label for Dr. De Jongh’s Light Brown Cod Liver Oil.


Cod Liver Oil. Causes of its Frequent Inefficacy and Means of Removing the Same; with Remarks upon the Superiority of the Light Brown over the Pale Oil, Directions for its Use and Cases in which the Oil has been used with the Greatest Effect, by Dr. De Jongh.


After 1860, steam-based mills replaced barrels and cauldrons. “This required more advanced technology and improved skills, and the old cod liver oil distillers were replaced by steam-based methods. The manufacture of cod liver oil had become an industry, and a high status job in the fishing village.” Said one retired cod liver oil worker: “Yes, it was a good job, except that the steam from the oil gave us such soft, fine skin, you know, like a baby’s bottom, and real men aren’t supposed to have skin like that.”6

The most common steaming method today, used since the early 1900s involves “leading steam under high pressure from an external boiler directly into a conical vat, with its point facing downwards, containing 5-6 hectolitres [about 1200 pounds] of liver. . . Steam with 3-5 kilos of excess pressure is led via piping to the bottom of the vat. . . The liver heats up to about 95o C [203o F] in 10-15 minutes. Good circulation is achieved in the liver pulp, while at the same time it is shredded by the powerful jets of steam . . . When the liver is warm enough, the pulp is left for half an hour until the cod liver oil has accumulated on top.”

According to this document, earlier, the dregs were tapped over into large cauldrons where they were left to ferment. This resulted in the emission of more cod liver oil: “sour oil” or “pale oil.” Then the dregs were reheated and pressed to produce a sour, dark “pressed oil” and a fatty liver cake used as animal feed. Today this process has been replaced by centrifugation. The document does not state whether or not this “sour oil” or “pale oil” was sold for medicinal use.6

The biggest impediment to cod liver oil use was the taste and smell—described by some as “highly disagreeable” or “nauseating,” although many people had no trouble taking it, especially mixed with water, juice or milk. The preparation of cod liver oil that was easier to take fell to Alfred B. Scott and Samuel W. Bowne who came up with an emulsified cod liver oil called Scott’s Emulsion. Their first trademark, registered in 1879, included the initials P.P.P. for “Perfect, Permanent, Palatable.” The formula was “50 per cent. of Pure Cod Liver Oil, 6 grs. of the Hypophosphites of Lime, and 3 grs. of the Hypophosphites of Soda to a fluid ounce. Emulsified with Mucilage and Glycerine.” The mucilage was probably gum acacia. One advertisement proclaimed, “You do not get the taste at all; because the little drops of oil are covered over in glycerine, just as pills are covered in sugar or gelatin.” By the 1890s, Scott and Bowne had factories in Canada, England, Spain, Portugal, Italy and France, and advertised their emulsion throughout the Americas, Europe and Asia.7

Today the product is owned by GlaxoSmith-Kline and seems to have faded from use except in the Spanish-speaking world. The ingredients for the modern product: “Water, cod liver oil, sucrose. Contains 2% or less of the following ingredients: phosphoric acid, tricalcium phosphate, monocalcium phosphate, vitamin A, vitamin D3, xanthan gum, propylene glycol alginate, modified corn starch, L-lysine, potassium sorbate.8

Note the addition of vitamins A and D; the natural vitamins are removed during processing. Recommended dosage is three teaspoons for children age nine and over, two teaspoons for children four to nine and one teaspoon per day for children under two years of age.


Over time, cod liver oil processing became more and more complicated. Vegetable oil processing began in the early 1900s, and much of that new technology transferred to cod liver oil manufacture. According to the book Fish Oils: Their Chemistry, Technology, Stability, Nutritional Properties, and Uses, published in 1967, “The processing of fish oils is similar to that of vegetable oils.”9

After steam extraction cod liver oil can be subjected to the following processes:10

1. Alkali refining, which uses caustic soda to remove free fatty acids and some metals. One of the reasons given for removal of free fatty acids is that they can interfere with other processing.

2. Bleaching, which removes color substances, metals and dioxins. This is a chelation-type of process that uses clay or other natural earth absorbents.

3. Winterization to remove stearines (saturated fats), usually by chilling down the oil and removing the congealed fatty acids. (Removal of stabilizing saturated fatty acids from cod liver oil makes no sense, but processors do it anyway.)

4. Deodorization, which removes pesticides, PCBs, most of vitamin D and quite a bit of the vitamin A. Other types of processing remove some vitamins, but it is the deodorization step that takes out the most. This is why most processors then add the vitamins back in, at doses of about 1100 to 4600 IU vitamin A per teaspoon and 180 to 460 IU vitamin D per teaspoon. These vitamins are single metabolite retinol palmitate and vitamin D3 made by irradiating lanolin with ultra-violet light. Deodorization is usually carried out by molecular or vacuum distillation, which places the oil under an extreme vacuum. This allows the oil to “boil” at a very low temperature. The various components of cod liver oil can be “boiled off” separately based on their molecular weight. This is how processors can take cod liver oil apart into its components—including omega-3 fatty acids and fat-soluble vitamins—often sold separately. As one manufacturer puts it: “Everything is purified molecule by molecule. There is very little mingling of molecules. The nasty mercury molecules stay in one place and the healthy Omega-3 in another. Now you have pure, concentrated fish oil. And no gunk.”11


Norwegian combined cooker for indirect and direct steam heating of cod livers.

5. Believe it or not, in some cod liver oil plants, the cod liver oil is hydrogenated! “In certain countries, it is desirable to manufacture a liquid oil of good stability through the hydrogenation of fish oils.”12 This is one reason manufacturers remove the free fatty acids, because these compounds interfere with the hydrogenation process.

The most recent description of industrial cod liver oil production we could find dates from 2011: “Generally, steam cookers are used to extract the oil from the livers. Low-pressure steam is piped into a tank containing the livers and the heat cooks the livers. When the steam condenses a layer of hot water is produced which floats the oil. The oil is then separated and pumped into a storage tank. Some liver oils are extracted at sea on board trawlers when they remain at sea for long periods of time.

“A process that treats the liver residue with caustic soda was developed in Iceland. After the medicinal grade oil is separated, the residue is then treated with caustic soda. This destroys the protein and the oil floats to the surface and is recovered as veterinary grade cod liver oil. This grade is darker in color and contains a higher level of vitamins than the medicinal grade [emphasis added].

In a more modern operation, the livers are ground and pumped over magnets to remove tramp metal, especially hooks which come from the freezing plants. The livers are heated and allowed to stand for a period of time to break down the proteins. The livers are then run through decanters to remove solids, and the liquor is collected in kettles, heated to 95°C and then separated. Modern three-way separators are used and the crude cod liver oil is collected and pumped to the refinery. In the refinery the oil is alkali refined to remove free fatty acids, washed and dried in a vacuum tower and then winterized to remove stearines [saturated fatty acids]. The result is medicinal grade cod liver oil.”13

“Consumption” and “wasting diseases” during the 1800s were a leading cause of death. These terms covered a variety of conditions we now know as manifestations of nutritional deficiencies, such as tuberculosis and rickets. Cod liver oil provided an effective treatment for these diseases, which brought untold suffering to those living in crowded, cold, dark tenements. Cod liver oil worked as well for rheumatism and gout.

In 1882, Koch discovered the tubercle bacillus—the “germ” associated with many cases of tuberculosis—and immediately fingered as the cause. The discovery launched a new era of science and medicine, with a search for “active principles” in traditional remedies. Scientists isolated plant alkaloids—morphine from opium and quinine from cinchona—in order to provide medicines with increased potency and known quantity, with the hope of more predictable results.

Investigators sought these active principles in cod liver oil. In 1888 French chemists Armand Gautier and Louis Mourgues published an analysis of the active principles in light brown cod liver oil, entitled “Sur les alkaloids de l’huile de foie de morue.” Like de Jongh of the previous generation, the French chemists expressed a preference for light brown over pale oil.6

With the emphasis on “active principles” and patent medicine, cod liver oil dropped out of favor with many doctors. The United States Dispensatory of 1918 summed up the prevailing attitudes: “Whether or not [cod liver oil] acts simply as a foodstuff or whether it has some direct influence on the bodily metabolism, is open to dispute.”6

But new research soon restored the popularity of cod liver oil. In 1913, in experiments with rats at the University of Wisconsin, Elmer McCollum and Marguerite Davies discovered vitamin A in cod liver oil; in 1922 McCollum found that cod liver oil also contained vitamin D, which protected against rickets. Early studies showed that cod liver oil cut deaths from measles,14 played a critical role in eyesight,15 and even reduces colds and absenteeism.16 In the years between 1926 and 1937, cod liver oil consumption increased threefold, from 1.9 million to 5.8 million gallons. Doctors, health care workers, journalists, government officials, teachers and even Sunday school teachers urged cod liver oil—children in orphanages and refugee camps got it every day.

After World War II, the germ theory of illness came to the fore, pushed into the limelight with the advent of antibiotics. Cod liver oil faded into the background and imports declined.

In the twenty-first century, cod liver oil has come to the fore again; antibiotics and other pharmaceutical “wonders” like vaccinations and a variety of “miracle” drugs have not saved us from what is now an epidemic of chronic disease; our children suffer from learning disorders, growth problems, crooked teeth, rampant caries, asthma, allergies, skin problems and even “adult” diseases like arthritis and cancer. Our search for answers accompanies a growing distrust of the pharmaceutical industry, of the fortification of processed food, of technologies that can heat and pound the life out of milk and take apart a traditional food like cod liver oil, replacing its natural vitamins with vitamins made in factories. The germ paradigm has fallen on its face with the discovery of the human biome, and we have gained a growing respect for fermented foods, once deemed unsanitary. Finally, a resurgence of interest in the work of Weston Price has led to the realization that we need the fat-soluble vitamins found in the much maligned animal fats.


As Chris Masterjohn has stated, cod liver oil is not so much a necessity as a convenience. The diets of the healthy primitive peoples Price studied were exceptionally rich in vitamin A and D, mostly from foods that modern people no longer eat, such as organ meats and blood, or from foods that are difficult to obtain, like butter, cheese and egg yolks from pastured animals. Price used cod liver oil in his practice “ . . . not because the healthy non-modernized populations he studied used it, but because it was a convenient way to increase the fat-soluble vitamin content in the diets of people who needed it. It provides retinol, the physiologically essential form of vitamin A, which can also be obtained from most animal livers, and, in smaller amounts from other animal fats, particularly butter and egg yolks. It provides vitamin D, which can be obtained from sunlight, many fish, and in lesser amounts from terrestrial animal fats, particularly butter and egg yolks. . . . It is easier to add cod liver oil to an imperfect diet than to perfect the diet, and for many people the most balanced approach to obtain all of these nutrients will be to consume a small amount of cod liver oil while also trying to hit the other dietary bases more often than not, allowing the cod liver oil to relieve the need for dietary perfection.”17

Fortunately, our choice of cod liver oil today is not confined to the industrially processed versions; today both brown and yellow versions of natural cod liver oil are available to us. Light reddish-brown, translucent fermented cod liver oil is now produced under carefully controlled conditions without heat or chemicals; it has a mild flavor and is easy to take.

Yellow cod liver oil with natural vitamins comes as “virgin” or “extra virgin.” According to an industry document, virgin cod liver oil “is separated from fresh cod fish livers using cold pressed and advanced purifying technologies without the use of chemicals. The raw material is processed very shortly after catching. The process involves heating to below 100oC, for example to a temperature around 90-95oC [194-203o F] just for the time needed for the material to pass through an indirectly heated tubular scraped surface heat exchanger. The heated suspension is then separated in a suitable decanter in order to isolate the oil. . . . An example is the Norwegian virgin cod liver oil production. The preparation of this product, including winterization, distillation, blending, drumming, and bottling is conducted in a manner that ensures the product is carefully processed to concentrate the healthy long chain omega-3 EPA and DHA fatty acids while removing any unwanted environmental chemicals and retaining the naturally occurring vitamins A and D.”18

According to the manufacturer, extra virgin cod liver oil is processed without heat, steam or chemicals, according to ancient Viking techniques, although we have not found a description in the industry literature. As with virgin cod liver oil, it retains the natural vitamins and has only a mildly fish smell.

These choices give us an advantage over what Dr. Price had to work with, which was most likely steam-extracted industrial cod liver oil. We also have a better grasp of the necessary factors for cod liver oil to be most effective: vitamin K from animal fats, especially duck and goose fat, aged cheeses, grass-fed butter and butter oil; plentiful dietary calcium and magnesium; and animal fats to supply arachidonic acid to balance the omega-3 fatty acids. We also know that the large doses recommended in the 1800s can be effective in certain situations over the short term but should not be continued for long periods.

And there is certainly much more to learn about cod liver oil and the fat-soluble vitamins it contains. Stay tuned!


South Sea Islanders put great store in fermented shark liver oil—enduring considerable danger to procure the sharks even though other, less dangerous-to-catch seafood was plentiful.

To prepare the oil, they put the livers inside the leathery stomachs of the shark and hang them in the trees for several months. As it ferments, the oil gradually comes out of the livers and fills the hanging stomachs! The yield is about one liter per shark.
Photo courtesy Kay Baxter.

1. 1000 Years of Cod Liver Oil: Lofoten as global manufacturer of cod liver oil.Norsk Fiskevaersmuseum, N-8392, Sweden
3. R A Guy. The history of cod liver oil as a remedy. American Journal Dis. Child. 1923;26.
4. 1000 Years of Cod Liver Oil: Lofoten as global manufacturer of cod liver oil.Norsk Fiskevaersmuseum, N-8392, Sweden
5. M E Stansby. Fish Oils: Their Chemistry, Technology, Stability, Nutritional Properties, and Uses. The Avi Publishing Company, Inc. Westport, Connecticut, 1967. Page 194.
6. 1000 Years of Cod Liver Oil: Lofoten as global manufacturer of cod liver oil.Norsk Fiskevaersmuseum, N-8392, Sweden
8. loz/024819862055/
9. M E Stansby. Fish Oils: Their Chemistry, Technology, Stability, Nutritional Properties, and Uses. The Avi Publishing Company, Inc. Westport, Connecticut, 1967. Page 207.
12. M E Stansby. Fish Oils: Their Chemistry, Technology, Stability, Nutritional Properties, and Uses. The Avi Publishing Company, Inc. Westport, Connecticut, 1967. Pp 213-214.
14. Ellison JB. BMJ 1932;2:708-11
15. A History of Vitamin A and Retinoids. The FASEB Journal, July 1996, 10:1102-1107.
16. Holmes AD and others. Indust Eng Chem 1932;24:1058-60.
18. Scientific Opinion on Fish Oil for Human Consumption. Food Hygiene, including Rancidity. EFSA Journal 2010;8(10):1874.


1937: When calcium plus viosterol (synthetic vitamin D2) was given to pregnant women, researchers found definite calcification of the placenta and indications of adverse effects (such as calcification of the kidneys) in newborns. No such effects occurred with calcium plus cod liver oil, a source of natural vitamin D (Ohio State Medical Journal 33(9):990-994).

1986: Cod liver oil prevented atherosclerosis in swine fed a highly atherogenic diet for eight months (New England Journal of Medicine 315(14):841-846).

2003: Supplementation during pregnancy and lactation with cod liver oil resulted in higher IQ in offspring at 4 years of age (Pediatrics 111(1):e39-e44).

2003: Use of cod liver oil during the first year of life is associated with lower risk of type-1 diabetes (American Journal of Clinical Nutrition 78:1128-34).

2004: Researchers relate the recent decline in cardiovascular disease mortality in Norway to increased use of cod liver oil, among other factors (Medisin Og Vitenskap 124:1532-6).

2005: Women who took cod liver oil during pregnancy were eleven times more likely to give birth to normal-weight babies, thus avoiding the many health problems to which low-birth-weight babies are prone (British Journal Gynecology and Obstetrics, April 2005).

2005: Multivitamin or cod liver oil supplementation was associated with a significantly lower risk of any fracture. “We found no evidence to support any skeletal harm associated with increased serum indices of retinol exposure or modest retinol supplementation in this population” (J Bone Miner Res. 2005 Jun;20(6):913-20).

2007: In Arctic climates, supplemental cod-liver oil during childhood may be protective against multiple sclerosis later in life (J Neurol. 2007 Apr;254(4):471-7).

2007: Reduced breast cancer risks were associated with increasing sun exposure and cod liver oil use from ages ten to nineteen. “We found strong evidence to support the hypothesis that vitamin D could help prevent breast cancer. However, our results suggest that exposure earlier in life, particularly during breast development, may be most relevant” (Cancer Epidemiol Biomarkers Prev. 2007 Mar;16(3):422-9).

2007: Regular use of cod liver oil is negatively associated with high levels of depressive symptoms in the general population (J Affect Disord. 2007 Aug;101(1-3):245-9).


This article appeared in Wise Traditions in Food, Farming and the Healing Arts, the quarterly journal of the Weston A. Price Foundation, Fall 2015

Sally Fallon Morell is the founding president of the Weston A. Price Foundation and founder of A Campaign for Real Milk. She is the author of the best-selling cookbook, Nourishing Traditions (with Mary G. Enig, PhD) and the Nourishing Traditions Book of Baby & Child Care (with Thomas S. Cowan, MD). She is also the author of Nourishing Broth (with Kaayla T. Daniel, PhD, CCN).

4 Responses to Constant Controversy

  1. Zek says:

    How about just eating the livers? How much to get the same as, say, 1 tsp of oil? I imagine fresh would be the best you can get?

  2. Lara says:

    Hi Dr. Fallon,

    Which brand of cod liver oil(s) do you recommend?

    Thank you,

  3. Lara says:

    I’m sorry, I mean to say “Morell”! 🙂

  4. Lacey says:

    Hi! I’m just now delving into cod liver oil and the benefits, what’s a good preferred brand now that so many add synthetics?? Thank you.

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© 2015 The Weston A. Price Foundation for Wise Traditions in Food, Farming, and the Healing Arts.