Cod Liver Oil's Incredible Immune Boosting Powers

There is abundant evidence that cod liver oil may be one of the best immune boosters that exists. Find out why it works better than lab-made vitamin supplements.

Note: much of the info for this post came from various articles in Dr. Chris Masterjohn’s Substack Harnessing the Power of Nutrients. He did his postdoctoral research on the interactions of vitamins A, D, and K so refer to his Substack for additional in-depth research.

In today’s article:

• How much CLO to take

• The History of cod liver oil (CLO)

• The evidence in favor of cod liver oil’s immune-boosting potential

• The mechanism by which cod liver oil boosts the immune system

• Is taking a vitamin A supplement just as effective as CLO?

• Are some CLOs rancid?

• What about vitamin toxicity?

History of cod liver oil:

• Hippocrates mentions the use of fish oils as medicine.

• In 1771, the British physician Thomas Percival showed that cod liver oil was more effective than a placebo at treating rheumatism.

• Around 1799, physicians began using it to effectively treat rickets (a disease caused by vitamin D deficiency).

• By the 1800s, cod liver oil was used to effectively treat eye infections and tuberculosis, the leading cause of infectious death.

• In 1848, the Royal Brompton Hospital in London published the results of the first five years of using cod liver oil (CLO) to treat tuberculosis. The British Medical Journal revisited these results in a 2011 article Cod liver oil and tuberculosis. Results showed that patients treated with CLO were over three times as likely to recover from tuberculosis.

• (Note: during the 1800s, physicians also began promoting the use of animal fats related to reproduction such as butter, egg yolks, and whole milk—my, how times have changed! These are also good sources vitamins A and D.)

• Between 1920 and 1940, interest in vitamin A as an immune booster grew as two researchers, Sir Edward Mellanby (who discovered vitamin D) and Harry Norman Green showed through research that vitamin A protected against infections of the eyes, lungs, tongue, throat, and GI tract. Here’s one of their papers titled Vitamin A as an anti-infective agent.

Researcher Richard Semba revisited Mellanby’s work and published an article in 1999 called Vitamin A as “Anti-Infective” Therapy, 1920–1940. He concludes:

After a pause of almost 50 yr, the value of vitamin A as “anti-infective” therapy was addressed again in controlled clinical trials, and these studies provided compelling new scientific evidence for the use of vitamin A as an important public health intervention.

(For anyone wanting to do a deep dive into vitamin A, Semba expanded this research into a book: The Vitamin A Story: Lifting the Shadow of Death.)

How Much CLO to Take

Take CLO with food, as is true of most supplements. Taking a number of supplements at once sometimes makes people nervous because they are thinking of the supplements as if they’re drugs. We all know that taking a handful of different meds at once can be dangerous. But don’t think of supplements in the same way. Most supplements are more effective when taken with food. Glycine or collagen from last week’s article is a good example. It does almost nothing when taken alone but all the benefits come when taking it with protein.

The standard CLO dosage for maintenance is 1 teaspoon per day of liquid or 2 capsules/day. I prefer Green Pasture Fermented Cod Liver Oil with butter oil because the fermentation process separates the oil without heat which gently preserves the vitamin D. The butter oil provides vitamin K2. This is what The Weston Price Foundation recommends.

You should not consume much more than the recommended dose unless prescribed by an integrative physician. Even then, higher doses are only necessary for a short amount of time. The regular dose can be continued for life.

Did you, like most people, have some Crisco-and-margarine-eating-years or decades in your past? If so, you might benefit from CLO to make up for lost nutrition. (Crisco is pure white because it has absolutely no vitamin content. Margarine would be white except it’s dyed orange.)

Do you have a history of avoiding egg yolks because of their cholesterol and steering clear of whole milk in favor of something that looks like water you cleaned a paint brush in? (I’m guilty of falling for the skim milk scam BUT my toddlers always had whole milk. I at least knew back then how important fat is for little ones’ developing brains.)

If so, you may benefit from CLO for a time, especially if you have frequent illnesses and/or autoimmune conditions. (Masterjohn argues that vitamins A and D keep fighter T cells from morphing into autoimmune Th17 cells that attack native tissues in his article New Evidence of Synergy Between Vitamins A and D: Protection Against Autoimmune Diseases).

Weston Price discovered what he referred to as “activator X,” a substance that greatly boosted the body’s ability to assimilate CLO. This later became known as vitamin K (Carl Peter Henrik Dam won the Nobel Prize in 1943 for identifying it but Price was writing in the 1930s just before vitamin K was named).

Since the 4 fat-soluble vitamins work together, you may want to supplement with E for a time in addition to CLO, especially if you’re recovering your health. I love this E supplement because it has mixed tocopherols and not just alpha tocopherols.

You can get vitamin K2 from fermented foods such as sauerkraut, egg yolks, hard cheeses, liver, and dairy products and butter from grass-fed animals. Vitamin E is high in animal fats such as fish and shellfish, olive oil, and butter.

The Evidence in Favor of Cod Liver Oil’s Immune Boosting Potential: Building up the Host Instead of Only Attacking the Pathogen