Everyone Should Be Taking This Cod Liver Oil

September 18, 2019lectinfreemama

Every year, I will the Earth to stop revolving around mid-July. Then I spend the next several weeks in denial until I open the door one morning and it’s 50 degrees with dead leaves rustling around. I seriously mourn the sunlight’s waning in the winter months, and I employ a number of strategies to beat the winter blues. One of those strategies is to start taking cod liver oil again after a few months hiatus over the summer (when I sunbathe instead).

The conflicting information regarding cod liver oil is enough to make my dreary head spin, though. Is flavor good or bad? Should it be fermented? Is liquid better than capsules? Will I burp fish taste all day long? Is there a vegetarian option with the same benefits? I hope to answer some of these questions for you in this post about cod liver oil: it’s benefits, the differences between various kinds, and what kind I personally take in the long, cold, dreary, depressing, dark winter months.

Which kind of cod liver oil you should be taking: fermented, extra-virgin, virgin, or plant-based.
This post contains affiliate links. Read my disclosure for more information.

Why Cod Liver Oil?

It is very difficult for those on a western diet (even a healthy, nutrient-dense one) to obtain the amount of vitamins and minerals that humans evolved to eat. Not long ago (relatively speaking), humans ate things like blood, fish heads, insects, and reptiles, in addition to organ meats, fish eggs, shellfish, and marine oil. Today, very few people could sustain this vitamin-rich type of ancestral diet if they tried. In fact, experts believe vitamin D deficiency is a modern global epidemic. Cod liver oil provides the naturally sourced vitamin A and D compounds that are missing from most modern diets. It’s also a major source of the omega-3 fatty acid DHA, which is even more lacking in our land-animal/vegetable oil heavy diet. (4)

Different Kinds of Cod Liver Oil


Fermented, or “rotten,” cod liver oil is extracted from cod livers that are predigested by lactic acid bacteria. This form of extraction is beneficial because the omega-3 fatty acids in marine oils go rancid when they are exposed to heat, light, and oxygen. Fermenting the cod livers prevents the fatty acids from going rancid by inhibiting the “autoxidation” process that produces toxins. This means no additional vitamins or preservatives have to be added. (2)


Extra-virgin cod liver oil is extracted by slightly raising the temperatures of the livers, which causes them to release oil. This oil is prone to oxidation, so vitamin E and something like rosemary oil is added to preserve the natural vitamins and prevent rancidity.


Processing may vary, but virgin cod liver oil may be extracted by cooling the livers to freezing temperatures, which “freezes” the saturated fat out, leaving behind the omega-3 fatty acids. Then the oil is distilled, blended, and bottled in a way that preserves the naturally occurring vitamins. As above, preservatives and vitamins are added to prevent rancidity.


Made from a 12-step (or more) process involving multiple high heat exposures that cause the the oil to go rancid and the naturally occurring vitamins to be destroyed. The toxins produced from rancidity are removed through bleaching. Synthetic vitamins, antioxidants, and flavoring are added to restore the benefits and prevent further oxidation. (4)

Benefits of Different Forms

All forms of cod liver oil contain omega-3 fatty acids DHA and EPA, which play a crucial role in the structure of our cell membranes, especially in the retina and the brain. They are less inflammatory than omega-6 fatty acids, and they play vital signaling roles in the cardiovascular, pulmonary, immune, and endocrine systems. (1)

Natural vs. Synthetic Vitamins

There are likely half a dozen or more vitamin D, vitamin K, and vitamin A compounds in unrefined cod liver oil. And probably some we don’t even know about. Experts theorize it’s not even the vitamins that make the difference–it’s the other compounds (many unknown) that increase the vitamin activity in the oil. (3)

Current testing methods are inadequate for measuring the exact amount of vitamins and vitamin compounds in cod liver oil. This is why it’s impossible to mimic the oil with synthetic vitamins. Industry experts are basically giving it their best guess as to what the vitamin profile should look like. An easy trick to see whether the oil has been industrially processed is to look at the vitamin amounts on the label. If you see specific measurements (i.e. 500 iUs), it means they’ve destroyed the natural vitamins and replaced them with synthetic versions.

Polyphenol Content in Cod Liver Oil

Fermented cod liver oil has one of the highest polyphenol and antioxidant contents of any food. The low-end estimate is on par with raw blueberries and almonds. The high-end estimate is about twice as much. (Again, current testing methods don’t allow for an exact measurement.)

The scoring for measuring antioxidants in food is called Oxygen Radical Absorbance Capacity (ORAC). Extra-virgin olive oil, which nutrition experts recommend for its polyphenol content, has an ORAC score of 372 per 100g. Fermented cod liver oil, on the other hand, has a score anywhere between 4333 and 7494.* That’s a lot of polyphenols (granted, we’re not usually pouring CLO onto our salads the way we do EVOO)! (5)

*Non-fermented brands range between 221 and 2838.

Rancidity Testing

The Weston A. Price foundation recently hired an independent lab to conduct rancidity experiments on 5 different brands of cod liver oil. These brands were:

Researchers tested the brands for signs of rancidity in both cold and room temperature conditions, light and dark, after 1 week and 6 weeks. All brands were fine after 1 week in a dark fridge. After six weeks, however, both brands of extra-virgin cod liver oil, no matter the conditions, contained toxic aldehydes. When kept in the light at room temperature, all brands except the Nutra Pro were rancid at 6 weeks. (4)

So Which Cod Liver Oil Should I Take?

The rancidity testing should not completely discount extra-virgin cod liver oil. Though it starts to go bad within 6 weeks, non-fermented, naturally extracted liver oil is a good choice for those with histamine intolerance. Buy the smallest bottle and, whatever you do, keep it in a dark fridge!

Fermented Arctic Mint

My personal preference is fermented cod liver oil. More specifically, this brand in Arctic mint flavor. I take a teaspoon or more of it a day, starting in September, while my daughter takes 1/2 teaspoon. The fermented oil and the flavor do not bother us. It’s quite pleasant-tasting.

Vegan/Vegetarian Option

There is a vegan and vegetarian option for those with dietary restrictions, fish allergies, or people who opt to go completely plant-based. Though they industrially extract it, Dr. Gundry’s plant omegas contain all of the beneficial omegas-5, -6, -7, and -9, polyphenols, plus vitamin E, present in algae.

Personally, I will never go back to industrial cod liver oil. It’s my humble opinion that no synthetically-enhanced oil can reproduce what nature has so well provided. There are immeasurable amounts of beneficial compounds present in this delicately extracted, nutrient-dense oil. Why mess with perfection?


  1. https://ods.od.nih.gov/factsheets/Omega3FattyAcids-HealthProfessional/
  2. https://www.greenpasture.org/blog/scientific-analysis-of-dr-jacob-friest/
  3. https://chriskresser.com/important-update-on-cod-liver-oil/
  4. Morell S.F. Update on Fermented Cod Liver Oil Wise Traditions; Summer 2019
  5. https://www.greenpasture.org/blog/orac-value-of-various-cod-liver-oils/


  • Rada

    September 24, 2019 at 11:11 pm

    Thanks for the heads up.

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