Cod liver oil is perhaps the world’s most misunderstood superfood. This article debunks common modern myths and identifies the truths that have maintained the importance of this ancestral supplement for over 2500 years.
First recorded by Hippocrates for medicinal use in Ancient Greece around 400 BC, cod liver oil has enjoyed a storied history ever since.
Ancestral cultures as diverse as the Eskimos and the South Seas Islanders both revered the use of fish liver oils for their health-giving properties, especially with regard to fertility and producing healthy children.
British physician Dr. John Hughes Bennett noted in 1848 that cod liver oil had been utilized since the beginning of recorded history by the fishing communities of Scotland, Sweden, and Norway for its strengthening properties as well as for medicine.
Doctors prescribed cod liver oil to treat rickets, a vitamin D deficiency disease, starting about 1800, perhaps even earlier.
A couple of decades later, in 1820, the practice of using cod liver oil to prevent and treat rickets was widespread in the countries of Germany, Holland and the Netherlands.
The anti-infective nature of cod liver oil due to the natural vitamin A content made it an indispensable remedy for all manner of illnesses prior to the advent of antibiotics including tuberculosis, measles, and diseases of the eyes.
According to the rare and fascinating book Ultraviolet Light and Vitamin D in Nutrition, the United States imported about 1.8 million gallons of cod oil and cod liver oil in 1922.
Five years later, in 1927, the amount nearly tripled to 5 million gallons due to research showing its benefits in preventing rickets.
In 2000, a mere 70 years later, America imported less than half a million gallons of cod liver oil, steep and shocking decline!
No doubt, the drastic move away from cod liver oil in the American diet was due to the foolish reliance of modern medicine on synthetic vitamins, antibiotics, and other pharmaceutical drugs to prevent and treat disease symptoms rather than nutrition and healthy lifestyle to prevent them.
Cod Liver Oil Resurges in Popularity
Since the turn of the millennium, cod liver oil has enjoyed a significant resurgence in popularity as interest in natural remedies and whole food supplements for maintaining wellness grows by leaps and bounds.
The worrisome problem of antibiotic resistance and the growing body of evidence that antibiotics can do significant harm and perhaps even irreparable damage to the gut has motivated forward-thinking individuals to look to the past for effective and safe alternatives.
Unfortunately, this interest has not been without controversy, as confusion and myths regarding this ancient superfood continue to make the rounds on social media, often in viral fashion.
The predominant myths about cod liver oil are discussed in the commentary below.
Myth #1: All Cod Liver Oil is Basically the Same
The truth is that almost all cod liver oil on the market today is heavily industrialized.
This destructive manufacturing process, which includes chemical refining, bleaching, high heat, and deodorization (oil kept at 482 °F/ 250 °C for up to 6 hours) destroys the natural vitamins A and D and damages fragile omega-3 fatty acids.
Synthetic vitamins are typically added back in to meet desired labeling requirements.
So many consumers are fooled by this!
Cod liver oil as used traditionally was not widely manufactured using this violent, denaturing process. Certainly, no synthetic vitamins were ever used.
As a result, if one desires the ancient benefits of cod liver oil, it is important to seek a manufacturer who produces this supplement using no heat or chemicals of any kind to preserve the natural vitamins A and D and prevent rancidity of the omega-3 fatty acids. (sources)
Myth #2: Dangerous Amounts of Vitamin A
It is very important that intake of natural vitamin A is balanced with its synergistic companion vitamin D (and ideally, Vitamin K2 as well).
Unfortunately, some cod liver oils on the market contain very little vitamin D. Worse, it is often synthetic.
Prolonged intake of cod liver oil that contains vitamin A with little vitamin D could lead to symptoms of osteoporosis and other health challenges, according to research performed in Europe.
If cod liver oil has been manufactured in a traditional manner with the natural vitamins A and D preserved in their correct ratios, these problems are avoided, and the benefits of this ancient supplement optimally enjoyed.
Myth #3: Toxins Such as Mercury, PCBs and Dioxins
Modern cod liver oil processing techniques effectively remove heavy metals and other toxins such as PCBs and dioxin.
Combined with traditional rendering methods and batch testing for purity, there is little need to be concerned about toxicity.
The one exception to this is radiation from the 2011 Fukushima nuclear disaster. As radioactive water is still pouring into the Pacific to this day, in my opinion, it is best to source cod liver oil that comes from Atlantic waters. (sources)
Myth #4: Plain Fish Oil is Better
The truth is that most fish oil on the market comes from farmed fish that are treated with antibiotics.
It is a little-known fact that farmed and “sustainable salmon” are fed more antibiotics per pound than any other livestock in North America!
In addition, noncarnivorous species of fish, such as salmon, will eat almost anything. For this reason, they are a popular source for commercial fish oil brands, and are commonly fed an unnatural diet that includes GMO soy and corn.
Another big issue with omega-3 fish oil supplements is that the vast majority of fish oils on the market contain little to no vitamins A and D!
Combined with the caustic chemical and high temperature processing damages the delicate omega-3 fats (EPA and DHA), fish oil is nothing short of a toxic supplement.
In fact, a 2026 study published in the Journal of Prevention of Alzheimer’s Disease found that older adults who take plain fish oil suffer faster cognitive decline than those that don’t take it! Note that the trial was not randomized, so the association is correlative, not causative.
My advice would be to stay far away from omega-3 fish oil supplements!
Myth #5: Good Source of Vitamin D
Most cod liver oil on the market is processed with molecular distillation, which removes most of the natural vitamin D.
Some manufacturers add it back in, but it is usually synthetic and in smaller amounts than would naturally occur in the oil.
Therefore, if one of the primary reasons for taking cod liver oil is the natural vitamin D, it is imperative to seek out a brand that is processed without heat. There are only a handful on the market that qualify, so buyer beware!
While everyone is different…for what it’s worth…this brand of virgin cod liver oil has demonstrated the ability to maintain my personal Vitamin D levels the best over the years.
Myth #6: Cod Liver Oil is Rancid
While MOST cod liver oil is indeed rancid due to high heat processing, there are a few brands of cod liver oil that are not.
Thus, it is important not to throw the baby out with the bathwater when it comes to cod liver oil!
Cod liver oil is an ancient superfood, and as long as it is processed in a manner consistent with traditional methods, it is wise to make use of its therapeutic and nutritive benefits!
According to my research, only two brands qualify as completely raw, unprocessed, and pure as of this writing.
Since 2015, our family has used this raw, Icelandic extra virgin cod liver oil. It is available in both plain and flavored liquid or capsules.
If Dropi is unavailable (it often runs low off-season), another brand to try is this raw, Norwegian virgin cod liver oil.
(1) Ultraviolet Light and Vitamin D in Nutrition
(2) Cod Liver Oil Debate
(3) Cod Liver Oil the Number One Superfood
(4) Cod Liver Oil: Setting the Record Straight
(5) The Yin and Yang of Cod Liver Oil
(6) Is Farmed Fish Really the Answer?
(7) The association between omega-3 supplementation and cognitive decline in older adults
More Information
How to Swallow Cod Liver Oil (without gagging)
Is it of utmost importance that you consume your fermented cod liver oil with pasture butter or butter oil at the same meal or is it OK to spread out your butter consumption through out the day even if you took your cod liver oil in the morning?
Hi – just wanted to comment.
For the lady who is battling cavities eventhough taking the FCLO and BO. All of us in our family are taking the same thing and have no new cavities, except for my oldest son.
We are working on his gut flora,(long story), but the gut has to be in optimal condition for you to absorb the nutrients in the FCLO/BO. Healing the gut takes time and I am not sure about the GAPS diet, as I tried it and developed new cavities (long story). But the fact of the matter remains that you all should be on a very good probiotic, lots of gelatin, and especially lots of K2 (raw milk cheese, natto, raw butter).
Hi Sarah,
Could you please answer to my question?
How much cod liver oil (the mix of butter oil and cod liver gel) should a pregnant woman take daily?
Thanks!
2 tsp/day is recommended
I don’t know the amount of A/D in the mixed, gel product so please contact the company on how much cod liver oil and butter oil is in each dose. Then you will have to do the math to work it out to come in line with recommendations for the Weston Price Foundation on the diet for pregnant and nursing women page.
I have to say that while I absolutely believe in FCLO and even unfermented in the right dosage and preparation…it is frustrating for me to know that Green Pastures s the only one on the market you recommend because it is really expensive and my family cannot afford the healthy diet and the supplement. The WAPF website lists a few other acceptable options. Why don´t you?
Its the only one that is fermented and whole. It may seem pricey, but one bottle will last one person 5 months or so, at one dose per day.
I agree. I even found a thread of other people who like me, have noticed nosebleeds and other problems after taking Green Pasture FCLO that weren’t there from just the plain stuff. After I finish this bottle I’m not planning to buy more from them. It is so acidic that it inflames my toddler’s skin on contact and gives her diaper rash.
I have been taking fermented cod liver oil since July 2012 and my elderly Mom, also.
Her vitamin D is always low and she just had her gallbladder removed last August. Do I need to order her some extra vitamin D or get her some bitters since she no longer has a gallbladder?
Hello Wendell,
I cannot answer about the Vit D as I think testing may be the only way to determine that. I did learn in nutrition school, however, that every person without a gallbladder should take bile salts with their meals. The gallbladder normally squirts out bile salts during the digestion process, emulsifying the fats. WIthout the gallbladder, the liver might drip bile all day long (if it’s not all clogged up) but it won’t be sufficient when the emulsifying job needs to be done. I’d send you a link to this info but I’m having some really funky stuff going on with my computer right now and can’t get to it.
I never new about fermented cod liver oil. I will tell you, however, that if it wasn’t for cod liver oil I would not be able to walk as I do now. I was literally unable to walk…unless you call very short shuffling walking. I could not pick up my legs enough to step over a sock on the floor. This is truth. Getting in or out of a tub was excruciating getting up from a sit was excruciating too. I lived on the 2nd floor of an apartment complex in that time. It was terror for me to have to go to the bathroom or better yet….to go outside for any reason. Yet I still had no choice about going out as I had to take my dog out. If I needed to go to the store for any reason it was much more terrifying! If I got to the car…could I get in? If I got in and made it to the store…could I get out? There were times I got in the car, got to the store and couldn’t get out and had to come back home and wait for someone to come along to assist me getting back up! (a long time of waiting) If it wasn’t for some show on Public access TV about cod liver oil and a study done I would not have known about its properties. It took 4 months of taking medicinal doses 3 times a day, which, first of all stopped the pain!…..then,in time, it healed me enough to actually walk and eventually take full strides! I give the glory to our Heavenly Father for all of this!
Love your newsletter but respectfully disagree on the use of fish oil and or cod liver oil..
It may be good in the short but not the long haul..and I use to take, but now I would not touch with a 10 foot pole…regardless where it came from….
Sid the article is about fish oil not fermented cod liver oil. There is a big difference. I am not surprised at the results of the study if the participants took plain old farmed fish oil. Read myth number 4. Just like you I would not take fish oil or cod oil… only fermented cod liver oil! I encourage you to read sarah other articles to help you understand the difference!
Me and my family take it but have not really seen any benefits. the dentist found 3 cavities at my last checkup and I have been cavity free for over 5 years. Been taking Green Pastures cod liver oil and butter oil for past year and a half at the WAP foundation recommended dosages. Also eat a full traditional diet for past 2 years which is very time consuming when you work full time outside of the home and have a family to feed. Wish all the extra time and effort was paying off.
I’m sorry it hasn’t been working out for you. Have you been eating oatmeal often? I’ve read that soaking does nothing for oatmeal, because it is always heat treated before being sold. I think it deactivates the phytase so the phytic acid can no longer be broken down.
Just a thought. I hope you find what works for you.
P.S. Paleo/Primal is like WAPF but with a generally quicker prep time (no soaking, sprouting, etc because no grains!).
I used to love Blue Ice, until Green Pastures raised their prices and stopped making my favorite kind… not good business. What a monopoly.
My boys love the cinnamon tingle fermented cod liver/butter oil!