New and innovative products often meet with skepticism, especially if they challenge existing industries or paradigms. Such is the case with fermented cod liver oil, a product introduced in 2006, which has caused a hue and cry among conventional scientists and manufacturers of competing products.
Although fermented fish products are fixtures in many traditional cuisines, they are not part of the American culinary tradition. Those unfamiliar with worldwide fermentation traditions have applied the terms “dangerous,” “rotten,” “rancid” and “putrid” to the new cod liver oil product. Yet testing shows that fermented cod liver oil is safe and even superior in many ways to today’s highly processed brands of cod liver oil.
ROTTEN VERSUS RANCID
Many concerns about fermented cod liver oil stem from confusion about the terms “rotten” and “rancid.” Rotten, putrified or fermented foods—including meat, fish and fat—are foods that have been predigested by bacteria. In an important 2017 paper published in PaleoAnthropology,1 anthropologist John D. Speth explains that “Because of the peculiar properties of many bacteria, including various lactic acid bacteria (LAB), which rapidly colonize decomposing meat and fish, these foods can be preserved free of pathogens for weeks or even months and remain safe to eat.”
Rancid is a term that applies to fats; rancidity in fats and oils occurs when they have been exposed to light, heat and oxygen. Under these conditions, fats and oils, especially the highly unsaturated omega-3 fatty acids that characterize marine oils, lose hydrogen atoms and become free radicals, and then break down further into small, highly reactive molecules called aldehydes. Aldehydes present in rancid or oxidized oils may contribute to cancer, arteriosclerosis, premature aging and many other adverse conditions.
Speth explains that the term “rancid” refers specifically to the degradation of lipids in meat or fish, an “autoxidation” process “quite distinct from what happens to lipids that are fermented or putrified. . .[E]thnohistoric and ethnographic literature frequently conflates these two processes and as a result can be quite confusing, if not downright misleading.”
Speth continues: “The preservative effects of LAB fermentation. . .are invaluable in preventing fats from becoming rancid. For arctic and subarctic people subsisting on diets that were composed almost entirely of animal foods, the large quantities of fatty meat and fish that such a diet demands can be very difficult to dry quickly enough and thoroughly enough to prevent the lipids, most especially the long-chain polyunsaturated fatty acids. . .from turning rancid and spoiling. . . .Such spoilage can actually pose a health risk by giving rise to a number of undesirable and potentially toxic substances in the meat or fish. The most important of these are a class of compounds known as hydroperoxides, unstable oxidation products that can undergo further breakdown, forming a variety of carbonyl group compounds such as aldehydes and ketones. . . .Fermentation provides an effective means of inhibiting the ‘autoxidation’ of the lipids that leads to rancidity.”2
Thus, among populations that consume high amounts of omega-3 in foods like fish and organ meats, it is the practice of fermentation that protects these fats against rancidity. As explained by Speth: “[A]erobic bacteria in the early stages of putrefaction deplete the supply of oxygen in the tissues, creating an anaerobic environment that retards the production of potentially toxic byproducts of lipid auto intoxidation (rancidity).” In other words, the practice of making foods “rotten” protects the fatty acids they contain from becoming “rancid.”
The acceptance or rejection of putrified meat is a culturally learned reaction. Whereas many Westerners react with revulsion to the sight and smell of putrified meat and fish, the latter are common among traditional cultures—from the Arctic regions to Africa to the South Pacific. These fermented foods include meat, liver and other organ meats, fish and shellfish, and even hooves and bones. Fermentation techniques include burying in the ground, preserving in bogs, placing in animal stomachs or preserving in sewn-up animal skins.
One putrified food that Westerners do enjoy is rotten milk—predigested, fermented and stored unrefrigerated for many months until it becomes covered with mold. It is called cheese—a delicious, highly acceptable food in the West—but which many Asians regard with disgust. In fact, the stinkier the cheese, the more we prize it—just as the Inuit prize stinky fermented fish. Listen to Inuit elder Mary Tyone talk about a native delicacy: “When we fix salmon head we put it in bucket in ground and we take it out and eat it. . . .Stinkfish, oooh, I love that stinkfish. Smell funny, but it sure taste good.”3
Another delightful European fermented food is salami. As Speth explains: “When a body starts to decompose, a forensic scientist would likely refer to what was happening as the onset of ‘putrefaction’. . .[A] food scientist dealing with pork sausages at exactly the same stage of decomposition would refer to the process as ‘fermentation’” [emphasis added].4
HYDROLYSIS VERSUS OXIDATION
As we have seen from the above discussion, “oxidation” refers to the breakdown of fatty acids into toxic components like aldehydes and ketones. This is not the same as hydrolysis, which refers to the chemical breakdown of triglycerides into individual free fatty acids and glycerol.
Hydrolysis of triglycerides is what happens during digestion. When we eat fats, our bodies produce bile, which breaks down the triglycerides into individual or “free” fatty acids. Since fermentation is basically a digestive process, we can expect to find a lot of free fatty acids in fermented fish products like fermented cod liver oil.
Triglycerides are composed of three fatty acids joined to a glycerol molecule, which is the way fats occur in nature. Typically, the middle fatty acid is the most unsaturated of the three, that is, the most vulnerable to oxidation. When a triglyceride is hydrolyzed into individual fatty acids, the middle fatty acid no longer has the protection of the other fatty acids on either side of it. The fish oil industry claims that the presence of free fatty acids in a fish oil is a sign of rancidity, but it is only the sign of potential rancidity. If the free fatty acids in the product are protected in some way, there will be no oxidation after hydrolysis.
In a fermentation process that involves no heat, and in which oxygen is removed from the product by lactic acid bacteria, the free fatty acids will be largely protected from oxidation.
Since this protection is absent in most fish oils, the oil refining industry removes the free fatty acids by treating the oil with caustic soda (sodium hydroxide), which converts the free fatty acids into insoluble soaps. After a reaction time of around thirty minutes, with slow stirring and a temperature of around 170 degrees F (hot enough to affect adversely the omega-3 fatty acids still bound as triglycerides), the industry then uses centrifugation to eliminate the water fraction and washes the oil with water to remove the remaining soap.
In addition to the protective environment afforded by lactic acid bacteria, a number of antioxidants are formed or released during the fermentation process. For example, polyphenols are natural antioxidants that occur in seaweeds and other marine algae. Levels of polyphenols in marine algae can reach up to 20 percent of dry mass.5 Studies have noted a linear relationship between the polyphenolic content of seaweed products and their antioxidant capacity, meaning that antioxidant capacity strengthens as polyphenolic content increases.6
While fish do not produce polyphenols directly, marine fish such as shad and other small schooling fish eat algae. Cod is an “apex predator,” feeding on other fish, including algae eaters, and so cod accumulates polyphenols in its flesh and oil.
FIGURE 1: Catechol and Catechin
Of the many different polyphenols found in algae, catechol and catechin (Figure 1) are found in nearly all species.
Catechol and catechin exert their antioxidant activity by trapping peroxyl radicals, which perpetuate lipid oxidation.7 The resulting compact structure, called an ortho-quinone, puts oxygen into a non-reactive double bond, thus halting destructive free radical chain reactions and giving stability to the oil.
Oxygen radical absorbance capacity (ORAC) is a method of measuring antioxidant, including polyphenol, levels in foods. Since 2012, the USDA has not allowed food companies to list ORAC levels in their products because there is no proof that the compounds producing the ORAC score have any physiological effect once consumed.
While it is true that the dietary polyphenols measured in the ORAC test are poorly conserved in the body (less than 5 percent), they do have an effect in the foods themselves—protecting fatty acids from degradation.
TABLE 1. ORAC scores for fermented cod liver oil, other cod liver oils and other high-antioxidant foods
An analysis by the Department of Food Science and Technology at the University of Nebraska found that the ORAC score of fermented cod liver oil was especially high, not only in comparison with other foods but compared with other brands of cod liver oil (see Table 1).8 The measured antioxidants are naturally occurring, from marine algae and the fermentation process; they are not antioxidants added after extraction of the oil.
In a recent study, researchers heated four brands of cod liver oil, including one brand of fermented cod liver oil, to 180 degrees C for up to ninety minutes. The concentrations of lipid oxidation products (LOPs), namely aldehyde, increased in each of the oils, with the lowest level of increase in the fermented cod liver oil. The “enhanced peroxidative resistivity” of the fermented cod liver oil product over the non-fermented samples was ascribed “to much higher levels of chain-breaking antioxidants (reflected by elevated ORAC values), and particularly aldehydic LOP-neutralizing amines” in the fermented cod liver oil.9
CAN COD LIVERS BE FERMENTED?
A legitimate concern about fermented cod liver oil is whether livers can even be fermented. Of course, it is not the oil that is fermented, but the livers, so that during the fermentation process the oil is released from the cells.
Cod livers contain between 1-2 grams of carbohydrate for every 100 grams of liver. The question is, can a food with such a low level of carbohydrate undergo lactic-acid fermentation? (It should be noted that proteins and lipids are also affected by the fermentation process, the former converted to biogenic amines and ammonia, the latter to free fatty acids and glycerol.)
The answer is yes. Typical fermentation processes require only 0.62 grams of carbohydrate per kilogram to lower the pH by 0.1 pH units. Based on a finding of 1 to 2 grams of carbohydrate per 100 grams of liver, this would give rise to a total drop in pH between 1.6 and 3.2 pH units. Assuming that cod livers have a neutral pH of approximately 7.0, the natural levels of carbohydrate they contain would be sufficient to lower the pH of the final fermented product to between 3.8 and 5.4 pH units.10
The process of extracting the oil from the cod livers begins with the addition of frozen cod livers to fermentation vats along with a starter culture and salt. The vats are then sealed and allowed to ferment. This process produces three distinct layers in the vats. At the bottom of the vat is the water that is separated from the cod livers during fermentation. The solid liver material and sediment float in the middle. An oil layer forms on top of the solids and sediment.
After the fermentation is complete, the top oil layer is extracted from the fermentation vat and centrifuged to remove all remaining water, sediment and liver material. This process not only removes the water from the oil, but also the water-soluble lactic acid (although traces of lactic, propionic and acetic acid may remain in the oil).
The pH of the water layer (brine) at the end of the fermentation process has been tested by MidWest Laboratories and found to be between 4.8 and 5.04. These pH values fall well within the normal pH levels accepted for the fermentation of raw meat products. According to the United Nations Food and Agriculture Organization (FAO), raw fermented sausages are only moderately acidic with a pH range of 5.0-5.5 and are safe for human consumption. The pH of safe cheese ranges between 4.8 and 6.0. The measured pH of the fermented cod liver oil itself ranges between 5.2 and 6.0.
WHY COD LIVER OIL?
The diet of healthy traditional peoples contained high levels of vitamins A and D from frequent consumption of liver and other organ meats, butter and egg yolks from pastured animals, marine oils like seal oil, fish eggs, shellfish and “weird” foods like blood, fish heads, insects and reptiles. It is very difficult for modern peoples to obtain high levels of these vitamins from the Western diet. Even if you eat liver frequently and have a source of butter and egg yolks from pastured animals, it is still difficult to obtain sufficient amounts of these vitamins. As explained by Chris Masterjohn, PhD, cod liver oil “is a valuable and convenient way to obtain vitamins A and D together with omega-3 fatty acids—all nutrients most Americans require in greater levels than they currently obtain through their diets.”
Masterjohn explains: “For centuries, cod liver oil has served as a valuable source of vitamins A and D and omega-3 fatty acids. It was a critical component of Weston Price’s program for reversing tooth decay, and many practitioners in his day used it to treat eye diseases, rickets and infections. Along with many other physicians, Dr. Price recommended cod liver oil to promote growth and general health in infants and children. Clinical trials proved that cod liver oil use in adults reduced absenteeism and saved millions of dollars’ worth of productivity for American industry.”11
However, as with any food, cod liver oil in both fermented and unfermented form is not for everyone. Those with a high sensitivity to histamines and other components of fermented foods will prefer the extra-virgin or virgin cod liver oils rather than fermented cod liver oil. Some people are deathly allergic to all seafoods and will need to obtain their A and D vitamins from other foods.
In some individuals, the omega-3 fatty acids in cod liver oil may cause a deficiency of arachidonic acid (AA), leading to skin problems, food sensitivities and other undesired effects.
This is because marine oils require balance with animal fats. Animal fats supply omega-6 arachidonic acid to balance the omega-3 fatty acids in cod liver oil. In addition, animal fats supply vitamin K2 to balance vitamins A and D, and they supply saturated fats to balance and protect the highly unsaturated fatty acids. Fortunately, in the Western diet, the fats of both land and sea are easily available.
The Weston A. Price Foundation contracted with an independent laboratory to test natural (unheated) cod liver oil under various conditions using nuclear magnetic resonance (NMR) testing. Green Pastures, Nutra Pro, Dropi and Rosita are U.S. brands and were ordered anonymously through their respective websites; Amorica, a U.K. brand, was ordered anonymously in the U.K. from the Amorica website.
The five brands of cod liver oil (two fermented, one “virgin” and two “extra virgin”) were tested under the following seven conditions:
Condition A: After one week, in the dark, at room temperature.
Condition B: After one week, in the dark, refrigerated at 4°C.
Condition B: After one week, in the dark, refrigerated at 4°C.
Condition C: After one week, in the light, at room temperature.
Condition D: After six weeks, in the dark, at room temperature.
Condition E: After six weeks, in the dark, refrigerated at 4°C.
Condition F: After six weeks, in the light, at room temperature.
The results are shown in Figure 2.
The testing indicated that all brands are safe on opening and at one week refrigerated if kept in the dark. One brand of extra virgin cod liver oil exhibited some instability at one week at room temperature, both in the light and in the dark. This may be due to high levels of aldehydes in rosemary oil, added as an antioxidant.
The more toxic alpha,beta-unsaturated aldehydes (Signals 1-4) appear at six weeks in both brands of extra virgin cod liver oil, under all conditions. The worst results appear in both brands of extra virgin cod liver oil at six weeks kept in the light at room temperature.
The less toxic saturated aldehydes (Signals 5, 6, and 7) appear in both brands of extra virgin cod liver oil and both brands of fermented cod liver oil at six weeks kept in the light at room temperature.
In conclusion, all brands of natural cod liver oil are safe on opening and at one week, under various conditions. However, at six weeks, the extra virgin brands of cod liver oil show the presence of toxic unsaturated aldehydes, especially if exposed to light.
Clearly, all types of cod liver oil should be sold in dark bottles and kept in the refrigerator or a dark cupboard. Extra-virgin cod liver oil should be kept in the refrigerator and consumed as soon as possible after opening. Fermented and virgin cod liver oil kept in the dark appear stable at room temperature, even six weeks after opening.
PRODUCTION OF EXTRA-VIRGIN AND VIRGIN COD LIVER OIL
EXTRA-VIRGIN COD LIVER OIL (EVCLO): In addition to fermentation, another natural way of removing the oil from cod livers takes advantage of the fact that a slight rise in temperature will cause the livers to release oil. Production of EVCLO begins with placing the livers in a dark, oxygen-free holding tank and then raising the temperature to slightly higher than the ocean temperature. Separation of the oil from the livers then takes place using a decanter, and contaminants are removed by a proprietary cold filtering process. Natural rosemary and full-spectrum vitamin E are added to increase shelf life and prevent oxidation. This process preserves the natural vitamins A and D in cod liver oil.
VIRGIN COD LIVER OIL (VCLO): A description of virgin cod liver oil production has been difficult to obtain. The pre-2010 Now Foods website described the process as including “winterization, distillation, blending, drumming, and bottling. . . 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.”13
METHODS FOR COD LIVER OIL TESTING
NMR: High-resolution nuclear magnetic resonance (NMR) spectroscopy is a state-of-the-art technique that involves the exposure of samples to an intense magnetic field causing the nuclei of the molecules to respond by producing an electromagnetic signal with a frequency characteristic of the magnetic field at the nucleus, allowing researchers to identify various components of the sample. NMR offers many advantages over alternative analytical techniques, since it allows the rapid, simultaneous, non-invasive and non-destructive analysis of a wide range of agents present in complex, multicomponent samples such as foods, oils, pharmaceutical formulations, health care products and biological fluids such as blood plasma and urine. Data acquired through NMR testing are presented as what is known as a spectrum consisting of a plot of signal intensity versus resonance frequency in parts per million (ppm, a dimensionless unit).
HPLC: High-performance liquid chromatography (HPLC), formerly referred to as high-pressure liquid chromatography, is a technique in analytical chemistry used to separate, identify and quantify each component in a mixture. It relies on pumps to pass a pressurized liquid solvent containing the sample mixture through a column filled with a solid adsorbent material. Each component in the sample interacts slightly differently with the adsorbent material, causing different flow rates for the different components and leading to the separation of the components as they flow out of the column. For oils, HPLC provides readings for peroxide value (PV) or primary oxidation and anisdine value (PA) or secondary oxidation. Another measurement of oxidation is thiobarbituric acid (TBA) and TBARS (a more involved version of the TBA test). The TBARS test is especially problematic for omega-3 oils as the method requires heating the samples for periods of about fifteen minutes. Heating causes peroxidation of polyunsaturated fatty acids, and hence all results derived from this heat-dependent test system are suspect. In addition, the TBARS is not a good technique for products containing phenols or residual proteins.
Spectrophotometry is a tool that provides a quantitative analysis of molecules depending on how much light is absorbed by colored compounds. Spectrophotometry uses photometers, known as spectrophotometers, which can measure a light beam’s intensity as a function of its color (wavelength). The spectrophotometer can generate a beam that goes through the sample (mainly transparent liquids). The colored compound in the sample will absorb the energy of the light, then the photometer can detect the absorption level of the light at a certain frequency on the other side. Based on the absorption level of the compound, the quantity of this compound can be calculated. As with HPLC, the sample must be heated to ascertain a TBARS value, so values obtained by spectrophotometry are considered less than reliable.
SPECTROPHOTOMETRY RESULTS FOR FERMENTED COD LIVER OIL.14
PV Peroxide Value: Very low
PA Anisdine Value: Very low
TBA Thiobarbituric Acid: Low
Free Fatty Acids: High
HOW INDUSTRIAL COD LIVER OIL IS MADE
GRINDING AND PRESSING is the first step in industrial cod liver oil production; the liver mass is then often heated to further separate the oil from the solids.
FILTRATION through carbon begins the refining process. This removes environmental pollutants like dioxins, furans and polyaromatic hydrocarbons (PAHs). This treatment is important for farmed fish and fish caught in highly polluted waters near industrial areas but is not considered necessary for wild fish.
DEGUMMING involves heating the crude oil to 212 degrees F and treating it with phosphoric acid. This removes the “gunk”—compounds like phospholipids, resins, proteins, minerals and other matter in the oil.
ALKALI REFINING or neutralization removes the free fatty acids that have formed during the earlier processing steps. This process produces soapy material that must be removed with water or steam washing, followed by centrifuging.
DRYING removes the moisture from the water washing. Drying involves heat, oxygen and light, which can cause further rancidity.
BLEACHING returns the now-darkened oil to a pale color. This step also removes the dangerous aldehydes that have formed during earlier steps.
WINTERIZATION involves cooling the oil to sub-zero temperature in order to remove the saturated fatty acids, resulting in an oil that has a higher concentration of fragile omega-3 fatty acids. In effect, winterization brings the levels of DHA and EPA back to normal levels since quite a bit of omega-3 has already broken down and been removed.
DEODORIZATION is the most damaging step. Temperatures reach 374 degrees F or higher as steam passes through the oil. This removes aldehydes, ketones, more pigments and compounds that give the oil a fishy smell or taste. This step causes the formation of some trans fatty acids in the EPA and DHA. Most seriously, deodorization destroys most of the vitamin D and a large part of the vitamin A naturally occurring in the oil.
MOLECULAR DISTILLATION, often used in place of deodorization, involves even higher temperatures, which can reach 392 degrees F. It removes environmental pollutants and destroys even more of vitamins A and D.
ADDITION OF SYNTHETIC VITAMINS is the next step. Most cod liver oil producers add synthetic vitamin A and vitamin D3 to replace the range of natural fat-soluble vitamins contained in unprocessed cod liver oil.
ANTIOXIDANTS are always added to conventionally processed cod liver oil for human consumption to protect the oil from further oxidation. These include “natural” antioxidants such as vitamin E tocopherols made from soy and spice oil extracts. The most common synthetic antioxidants are BHA (butylated hydroxyanisole), BHT (butylated hydroxytoluene), TBHQ (tert-butylhydroquinone) and propyl gallate.
ADDITION OF FLAVORINGS to cod liver oil is common, especially citrus flavorings, derived from the peel of lemons or oranges and often containing other proprietary ingredients.
1. Speth JD. Putrid meat and fish in the Eurasian Middle and Upper Paleolithic: Are we missing a key part of Neanderthal and modern human diet? PaleoAnthropology 2017:44-72.
2. Speth, p. 11.
3. Godduhn AR and Kostick ML. Harvest and Use of Wild Resources in Northway, Alaska, 2014, with Special Attention to Non-salmon Fish. Technical Paper No. 421. Anchorage, Alaska: Alaska Department of Fish and Game, Division of Subsistence; 2016:30.
4. Speth, p. 11.
5. Van Alstyne KL, McCarthy III JJ, Hustead CL, Duggins DO. Geographic variation in polyphenolic levels of Northeastern Pacific kelps and rockweeds. Marine Biology 1999;133:371.
6. Maqsood S, Benjakul S, Abushelaibi A, Alam A. Phenolic compounds and plant phenolic extracts as natural antioxidants in prevention of lipid oxidation in seafood: a detailed review. Compr Rev Food Sci Food Saf 2014;13:1125.
7. Tejero I, Gonzalez-Garcia N, Gonzalez-Lafont A, Lluch JM. Tunneling in green tea: understanding the antioxidant activity of catechol-containing compounds. A variational transition-state theory study. J Am Chem Soc 2007;129(18):5846-54.
8. “ORAC value of various cod liver oils.” https://www.greenpasture.org/blog/orac-value-of-various-cod-liver-oils/.
9. Percival BC and others. Evaluations of the Peroxidative Susceptibilities of Cod Liver Oils by a 1H NMR Analysis Strategy: Oxidative Resistivity of a Natural Antioxidant- and Biogenic Amine-Rich Fermented Product. 2019. In preparation.
10. Friest JA. Fermented cod liver oil (FCLO): Investigation of Green Pastures fermentation process and food safety implications. Oct. 27, 3015. https://www.greenpasture.org/blog/scientific-analysis-of-dr-jacob-friest/.
11. Masterjohn C. The cod liver oil debate: Science validates the benefits of our number one superfood. Wise Traditions; Spring 2009. https://www.westonaprice.org/health-topics/cod-liver-oil/the-cod-liver-oil-debate/.
12. Masterjohn C. Precious yet perilous: understanding the essential fatty acids. Wise Traditions; Fall 2010. https://www.westonaprice.org/healthtopics/know-your-fats/precious-yet-perilous/.
13. “Quality & safety.” www.nowfoods.com/Quality/QualityNotes/M099609.htm
This article appeared in Wise Traditions in Food, Farming and the Healing Arts, the quarterly journal of the Weston A. Price Foundation, Summer 2019