Cod liver oil vs fish oil vs krill oil depicting gelcaps in a white bowl on a black background by The Healthy RD

Cod Liver Oil vs. Fish oil vs. Krill Oil: Which is Best?

When comparing cod liver oil vs. fish oil, there are some important factors to keep in mind.  These factors include your health goals, safety, effectiveness, vitamin content, and quality. 

No doubt, most people need more fish and omega 3 fats in their diets. But if you go to the effort of buying a supplement, you should become an informed consumer about when to buy cod liver or fish oil. 

Sure, we all should eat more fish regularly in our diets.  However, eating fatty fish is often more costly than supplementing the diet most of the time.  You need to eat about 3 ounces of salmon per day to equal the number of grams of omega 3’s in a single cod liver or fish oil supplement too. 

You may be wondering, is cod liver oil the same as fish oil?

Quick answer: no, they have some distinct differences.  

For most people, cod liver oil is the best choice and I’ll explain why.  Keep in mind, there are some exceptions, and in this post, I will review when to take fish oil instead of cod liver oil too.

This post contains affiliate links. Read more on my disclosure page.


Why choose cod liver oil over fish oil?

Cod liver oil is an extract of oil from the liver in codfish.  It is important to know that cod liver oil is much richer in vitamins than fish oil. 

Cod liver oil benefits for health are due to its rich nutrient and omega 3 fatty acid content. Traditionally, people supplemented cod liver oil as a nutritional supplement for children and adults alike.  

This concentrated nutrition supplement may reduce the risk of diseases and reduce the severity of diseases like:

Tip: Cod liver oil is available in both liquid and capsules.  If you don’t like the taste of fish, go with the capsule form. 


Nutrients in cod liver oil

Arctic cod liver oil is a great source of vitamin A, omega 3 fatty acid, and a good source of vitamin D. Here is the breakdown of these nutrients:

Vitamin A

Vitamin A is an antioxidant.  In its active form called retinol, it is critical for a healthy immune system, healing skin tissue, eye health, memory, regulating genes, and heart health.

I will walk you through when you will need to watch out for too much vitamin A.  Most importantly, I review why you may need more vitamin A from food sources like cod liver. 

Here are 6 reasons vitamin A from cod liver oil is healthy.

  1. A good cod liver oil contains between 1000-5000 IU of vitamin A per teaspoon, or around 20-100% of the RDI for brands like Carlson or Garden of Life Icelandic Cod Liver Oil.
  2. This is important because vitamin A levels are low for more people than we probably realize due to a variety of genes that control beta carotene absorption or vitamin A metabolism. 
  3. Also, the vitamin A from cod liver oil is absorbed well: around 70-90% vitamin A from cod liver oil is absorbed into your bloodstream.
  4. In contrast, only 3% of plant forms of vitamin A are absorbed, on average (read more in the Pros and Cons of Veganism).
  5. When you also consider that most people avoid eating vitamin A-rich foods like liver, the case for taking cod liver oil vs fish oil becomes even stronger.
  6. People eating a high protein diet or those taking beta carotene supplements have increased vitamin A requirements. 

But there is some controversy about taking cod liver oil because it may raise your vitamin A levels to toxic levels. 

Are you getting too much vitamin A?

It’s possible to get too much vitamin A, but does this concern happen in real life? 

Rarely. In fact, less than 10 cases of vitamin A toxicity occur per year, according to research. As long as you eat less than 10,000 IU per day of vitamin A (the tolerable upper limit), you won’t get too much. 

This tolerable upper limit gives a range of safety around it as well, and according to data from the National Health and Examination Survey,  a third of Americans don’t even meet the bare minimum estimated average requirements. 

To learn more about vitamin A, visit Weston Price.


Vitamin D

It’s no secret by now that almost everyone is low in vitamin D. One of the best natural food sources of vitamin D on the planet is cod liver oil. 

Don’t rely solely on cod liver oil for vitamin D deficiency, but it can be helpful because it typically contains around 200 to 400 IU of vitamin D per teaspoon.  

Most people need much more vitamin D than that, however. 

You still need a good amount of vitamin D from the sun, which can provide up to 25,000 IU per sun exposure, to get enough vitamin D for a healthy body. Note that taking vitamin D may increase your need for vitamin A too and vice versa. 

Most people don’t get enough sun either!  This is due to cold climates, sunscreen, and working indoors.  Read more about testing vitamin D here


Vitamin E

Cod liver oil may also be a natural source of vitamin E.  According to, cod liver oil may contain a concentrated source of natural vitamin E because the flesh of fish is rich in vitamin E. 

However, it is not possible at this time to find out exactly how much vitamin E is in cod liver oil, so I recommend focusing on getting the best natural vitamin E from other sources. 


Omega 3 fats

The omega 3 fats in cod liver oil are essential fatty acids that help the body in so many ways. 

  • Docosahexaenoic acid (DHA) is the brain omega 3
  • Ecosapentaenoic acid (EPA) is the anti-inflammatory omega 3 fatty acid

Cod liver oil contains high amounts of both DHA and EPA, so this is why it helps both the body and the mind.

For example, a teaspoon (5 ml) of cod liver oil, such as Nordic Naturals brand, contains 550 mg of DHA and 340 mg of EPA with 210 mg of other omega 3 fats. 

The difference between cod liver oil and fish oil in regards to essential fatty acids is that cod liver oil is higher in DHA than EPA and the reverse is often true of fish oil: it is higher in EPA than cod liver oil and lower in DHA. 


What about pollutants and contaminants?

A concern about cod liver oil and fish oil alike is that they might contain toxins like persistent organic pollutants or mercury due to the water quality where the fish live.  However, toxins aren’t a concern in high-quality cod liver oil supplements and fish oil supplements due to improved purification methods. 

Pharmaceutical grade cod liver fish oils like Carlson, Vital Nutrients,  and Barlean’s are free of contaminants and are molecular distilled.  However, Barlean’s brand cod liver oil doesn’t contain any vitamin A, which is a drawback. 

A gelcap brand that is certified free of mercury and pollutants and is also in a convenient gelcap in the Now Brand Cod Liver Oil


Cod liver vs fish oil: when is fish oil best? 

There are two big differences between cod liver oil and omega 3 supplements:

  1. Omega 3 fish oil supplements typically don’t have any vitamins while cod liver oil does
  2. Fish oil is extracted from many different types of fish, such as salmon oil, herring, sardines, and krill, whereas cod liver oil is from codfish alone.

There are some occasions where it is best to choose omega 3 fish oil supplements instead of cod liver oil supplements. 

If you answer yes to the following questions, you should consider taking fish oil instead of cod liver oil:

  • Do you take a multivitamin that contains more than 50% of the daily value for retinyl palmitate or retinol?
  • Do you take a separate vitamin A supplement made of retinol or retinyl palmitate?
  • Is your primary goal for taking omega 3’s to reduce triglyceride levels or reduce cholesterol?
  • Are you pregnant and already taking a prenatal vitamin with more than 50% of the daily value for retinol or retinyl palmitate?
  • Do you take Accutane (Isotretinoin)?

You can still take cod liver oil to help improve your triglycerides, but sometimes your doctor or healthcare provider will recommend a high dose, and this may put you in danger of getting too much vitamin A. 

For reference, again, the tolerable upper limit of vitamin A is 10,000 IU (3,000 mcg) per day. 

Cod liver oil vs fish oil vs krill oil infographic by The Healthy RD

How to choose a good fish oil

If you choose to take a concentrated fish oil supplement, you should still look for a pharmaceutical grade brand like Nordic Naturals or Vital Nutrients. 

Also, make sure to avoid fish oil that contains synthetic vitamin E and make sure it contains natural tocopherols instead, like the brands I mentioned above. 


Is Krill oil better than fish oil? 

Krill oil is a special kind of fish oil derived from krill, which are tiny oily fish that are thought to be healthier than regular fish oil. 

This is because the fat may absorb better than most types of fish oil because it is in the form of phospholipids instead of triglycerides. It is also rich in an antioxidant called astaxanthin, which is linked to all sorts of improved health. 

That said, krill oil usually contains much less total omega 3 fats than other kinds of fish oil and it is often more expensive. Still, at a much lower dose, krill oil has the same cholesterol-lowering effects as fish oil. 

So, krill oil is a better choice than fish oil if you don’t like taking a big pill. And astaxanthin itself may reduce harmful cholesterol. 

Another reason to choose krill oil like Schiff Mega Red or Dr. Mercola Krill Oil is that it is a natural source of antioxidants like astaxanthin, which are good for eye health. 

Tip: regardless of the type of fish oil you choose, make sure it is from a sustainable source as well.

Krill oil vs cod liver oil? 

As far as I can tell, there has never been a study that has directly compared the effects of cod liver oil compared to krill oil.  

Krill oil and cod liver do have one thing in common: both have phospholipids in them, which means they both probably absorb better than typical fish oil brands according to one study. 

Both contain antioxidants too, albeit different ones: 

Tip: both krill oil and cod liver oil are superior to most fish oils because they absorb better and have more antioxidants.  You could try switching back and forth between krill oil and cod liver oil to optimize your antioxidant intake or take low doses daily of both. 


Timing of supplements and doses

You can take cod liver oil, krill oil, or fish oil at any time of the day, but for best tolerance, taking it with food is a good idea. 

Taking small doses twice a day is a great option too if you are new to taking fish capsules or liquids. 

The dose you need depends on the reason you are using it, but typically, one to two gelcaps a day of fish oil or 1 teaspoon of cod liver oil, or 1 gelcap of cod liver oil is recommended. 

Make sure to avoid fish oil or cod liver oil if you are allergic to fish or seafood. 


Reasons to take cod liver, krill, or fish oils

Research studies consistently demonstrate that getting more omega 3 fats in the diet benefit all aspects of health. 

A recent study projects that by optimizing omega 3 levels for people by simply supplementing omega 3’s, we would save $1.7 billion dollars in hospital costs per year alone.    

Not only would we save money that way, but we would also save money in countless other ways.  We would also improve the IQ of children too according to research.  

Here are some potential preventive uses for cod and fish oils as part of a healthy routine:

  • Joint pain
  • Hormone health
  • Anxiety
  • Depression
  • Mood disorders like bipolar disorder and schizophrenia
  • Heart health
    • Congestive heart failure
    • Angina
    • Coronary artery disease
  • Seizures
  • Healthy skin
    • Eczema
    • Psoriasis
    • Reduced wrinkles
  • Asthma
  • Diabetes
  • Eye health
  • Brain development
  • Dental health
  • Autoimmune disorders
    • Lupus
    • Multiple sclerosis
    • Rheumatoid arthritis
    • Colitis
  • Immune health
  • Alzheimer’s dementia

This all makes sense if you consider that omega 3 fats are essential fatty acids and almost everyone can stand to get more of them in their diet. 

Tip: When considering cod liver oil vs fish oil for these conditions, remember that cod liver oil and krill oil contains anti-inflammatory vitamins while purified fish oil does not. 



Taking fish supplements has a long tradition of supporting heart health and reducing the risk of chronic diseases and studies show that taking fish oil and cod liver oil is beneficial for many people. 

When deciding between cod liver oil vs fish oil, remember that cod liver oils and krill oils contain more antioxidants and are better absorbed than most types of fish oil supplements. 

Still, there are reasons some people should avoid cod liver oil and choose a fish oil supplement instead, such as taking supplements that already contain vitamin A in retinol form. 


The information on this website has not been evaluated by the Food & Drug Administration or any other medical body and is shared for educational purposes only. Consult your doctor or healthcare provider before making changes to your supplement regimen or lifestyle.

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