Cod Liver Oil vs. Fish Oil: Which is Better?

06/19/2021 | 7 min. read

Unless you’ve spent the last couple of decades under a rock then there is a good chance you’ve heard the term omega-3s at some point. In fact, it would probably be impossible to stroll through the supplement aisle without seeing a whole row of fish oil.

The use of fish oils is nothing new. Studies for the use of fish oil as a supplement began in the 20th century; cod liver oil, on the other hand, has been around much longer.

They both contain omega-3s and they both are derived from fish. So, what’s the catch — besides fish? Although these two supplements share many of the same benefits, they are marked by some important differences.

But which is better? Who gets to be the catch of the day?

A Little History on Fish Oils

Before we jump into exploring each in detail, it is important to get a historic view on the use of fish oil.

Fish Oil, Good Enough for the Ancients

Did you know that the practice of harvesting fish oils dates back to ancient Rome? This practice can be traced back to roughly the 8th century. Of course, the ancients didn’t pick their fish oil supplements at the nearest vitamin store — their fish oil was saucy, literally.

Garum, a fish oil-based sauce, was wildly popular among the ancients, it was even exported as far as Britain. But it wasn’t cheap. It is thought that they coveted this stinky dish for its uses as an aphrodisiac and a headache cure.

Fish Oil in the 19th Century



If we press fast forward we find a boom in fish oil use during the Industrial Revolution. The rise of industrial practices in major cities, especially in London, brought industrial smog. This led to a condition known as rickets in many children of the time.

Rickets is essentially a weakening of the bones in children caused by vitamin D deficiency. Once it was figured out that a combination of poor diet, bad air, and lack of sunshine brought about the rise of vitamin D deficiency the research began.

Cod liver oil became the method of choice to treat the malady. But thanks to the work of Norwegian pharmacist Peter Möller, this fish liver oil didn’t come as a stinky sauce.

Fish Oil Use in Modern Times

The health benefits and importance of omega-3 fatty acids saw their rise in the early 20th century thanks to the nutritional research by George and Mildred Burr. More research was conducted in the 1960s and 70s among the Inuit people of Greenland.

Researchers found that despite the Inuit’s fatty diet (fish, whale, and seal) they were much healthier, especially their lipid levels, compared to the average American.

It was concluded that their large consumption of EPA and DHA (omega fatty acids) was a reason for their low incidence of heart disease.

Since then, fish oil supplements and interest in omega-3 fatty acids have skyrocketed.

Omega-3 Fatty Acids

Before we get to the showdown between cod liver oil and fish oil it is important to note one huge similarity: Omega-3 fatty acids. Each comes packed with omega-3s — but what are they exactly?

Omega-3 fatty acids refer to a family of polyunsaturated fatty acids (PUFA) — polyunsaturated refers to their carbon bonds. There are actually two groups of PUFA: Omega-3s and omega-6s. Our concern is with the former.

Although there are several different omega-3s, most of the research has been focused on three primary types:

  • Alpha-linolenic acid (ALA)
  • Eicosapentaenoic acid (EPA)
  • Docosahexaenoic acid (DHA)

These fatty acids are considered essential, which means they can only be obtained through dietary sources — food or dietary supplements. ALA is found mainly in plant oils: Soybean, flaxseed, etc.

EPAs and DHAs are present in cod liver oil, fish oil, krill oil, and even squid oil. Of course, they are also consumed through various seafood: Tuna, salmon, oysters, shrimp, sardines, cod, etc.

What’s interesting is the fact that omega-3s come to fish by way of phytoplankton, which comes by way of microalgae. Quite the voyage.

Health Benefits of Omega-3s

Omega-3s get their claim to fame as potent allies to overall cardiovascular health and function. Even the American Heart Association (AHA) reminds us to eat fish rich in omega-3s at least twice a week.

Per the AHA, omega-3s have cardiovascular benefits in the following areas:

  • Helping to manage triglyceride levels
  • Promoting healthy blood pressure
  • Aiding cardiovascular circulation, blood flow, and blood viscosity
  • Promoting healthy cholesterol levels
  • Decreasing cardiovascular disease risk factors among healthy adults

Omega-3s have also been linked to benefits in infant health and neurodevelopment, cognitive function, age-related macular degeneration, and inflammation. Other research areas being explored include depression, ADHD, and cystic fibrosis.

For adults, adequate intakes — levels that ensure nutritional adequacy — of omega-3 fatty acids are 1600 mg for men and 1100 mg for women (1400 if pregnant).

The typical fish oil supplement provides around 1000 mg of omega-3s. But they are also present in other dietary supplements, besides fish, krill, squid, and cod liver oils. Plant-based omega-3s are also available in algal oils, but usually contain much lower amounts of DHA and EPA.

Cod Liver Oil vs. Fish Oil

We’ve looked at the history of fish oils and at their number one claim to fame, omega-3s. Now it is time to look at some of the differences between cod liver oil and fish oil.

Cod Liver Oil

It is as the name suggests. Cod liver oil is derived from the livers of cod fish; both Atlantic and Pacific cod. That is an important distinction to make. It is pressed from the liver of the cod fish and the liver only.

As mentioned, its history of use goes back to the 19th century where it was first used widely to treat rickets — a condition due to vitamin D deficiency.

Although both cod liver and fish oil boast many of the same health benefits, the main difference between the two lies in vitamin content.

Vitamin A and D in Cod Liver Oil

Cod liver is known for having high levels of fat-soluble vitamins A and D, in addition to omega-3s. Vitamin A is known for being an important vitamin for eye health, the immune system, and even reproduction.

The recommended daily amount for adults is roughly 700 – 900 mcg. Most cod liver oil regiments put your vitamin A intake at 90% of the daily intake level — some even exceed the recommended levels.

Cod liver oil is also known for its vitamin D content, which is why it helped treat rickets. Vitamin D is also essential for calcium absorption, which is important for bone health.

Some Cautions

The biggest caution leveled against cod liver oil is its derivation. Some have voiced concerns over the potential for bioaccumulation of environmental pollutants (heavy metals) in cod liver oils. This is due to the fact that the liver, as an organ, is used in the filtering of toxins and contaminants.

Other concerns over its use are ecological, such as the overfishing of certain species.

Fish Oil

Most fish oils are derived from bodies of oily fish: mackerel, tuna, herring, salmon, sardines, and anchovies. These oils are usually pressed from the whole body of the fish, rather than one specific organ.

Fish Oil and Omega-3 Content

Fish oils do not boast the same amount of vitamin A and D content as cod liver oils. However, they are thought to contain much higher omega-3 content — up to three times more. The liver of the cod fish, though dense in vitamins, is less fatty than oily fish. Therefore, the omega-3 fatty acid content tends to be much richer in whole body-pressed fish oils.

Which Is Better?

At the end of the day, both cod liver oil and fish oil boasts many of the same benefits, especially in regard to heart health. Both are rich in EPA and DHA omega-3s. However, whole body-pressed fish oils are known for having a much higher content.

In light of this, and the potential bioaccumulation of toxins and environmental concerns of cod liver oil, the upper hand must go to fish oil.

However, be aware that any fish oil supplement could trigger fish allergies. Also, fish oil supplements have been known to cause some stomach issues (bloating), and some can taste rather — fishy.

Final Thoughts on Fish Oils

Fish oils (and sauces) have been used for centuries. However, the discovery of omega-3s and the associated heart health benefits sent their popularity soaring — or swimming in this case.

Of course, one of the best ways to enjoy the benefits of omega-3s and a healthy heart is by eating fish. However, if fish aren’t your thing, omega-3 supplements are also available, rich in both DHA and EPA fatty acids.

Either way, it’s time to get your fish on.