Cod Liver Oil vs Omega-3 Fish Oil: How Are They Different?

Omega-3 fish oil is a supplement made from the oils found in fatty fish such as anchovies, sardines, and mackerel. It contains two key omega-3 fatty acids—EPA and DHA—that the body cannot produce on its own, so they must come from food or supplements.

These fatty acids boast significant anti-inflammatory properties and can help to support healthy cell function throughout the body.

Key benefits include:

• Cardiovascular health: EPA and DHA help maintain healthy triglyceride levels and support overall heart health, which may help prevent heart disease.

• Cognitive function: DHA is a major structural component of brain tissue and plays an important role in memory, focus, and long-term brain health.

• Exercise recovery: Research shows omega-3 supplementation may reduce markers of muscle damage and inflammation after intense exercise. 

• Joint health: Because omega-3s help regulate inflammatory pathways, they may also reduce joint pain and help improve mobility. 

Most modern fish oil supplements are concentrated and molecularly distilled, meaning they deliver higher levels of EPA and DHA while removing contaminants such as heavy metals.

Cod liver oil is a traditional supplement made from the liver of Atlantic cod. Like fish oil, it contains the omega-3 fatty acids EPA and DHA, which help support heart, brain, and inflammatory health. However, cod liver oil also has naturally occurring vitamin A and vitamin D content.

Key benefits include:

• Omega-3 support: Cod liver oil provides EPA and DHA that help support cardiovascular health, brain function, and inflammatory balance.

• Vitamin A: Naturally rich in preformed vitamin A (retinol), which supports healthy vision, immune function, and skin health.

• Vitamin D: A natural dietary source of vitamin D, which helps support bone strength, immune health, and mood regulation.

• Historical use: Cod liver oil has been used for centuries in northern climates to help prevent Rickets, a condition caused by vitamin D deficiency.

Because cod liver oil comes from the liver, where fat-soluble vitamins and certain compounds accumulate, its vitamin A levels and purity standards require careful attention. High-quality products are purified to help reduce contaminants while preserving beneficial nutrients.

While cod liver oil supplements and standard fish oil both provide beneficial omega-3 fatty acids, they differ in nutrient composition, concentration, and sourcing.

EPA and DHA Concentration

One of the biggest differences is the amount of EPA and DHA per serving. Standard fish oil supplements are typically concentrated to deliver higher levels of these omega-3s. For example, Momentous Omega-3 provides 1,600 mg of combined EPA and DHA per serving, while many cod liver oil products provide 500–800 mg or less.

Because of this, fish oil is often preferred when the primary goal is cardiovascular health, cognitive support, or exercise recovery, where higher EPA and DHA intake may be beneficial.

Vitamin Content

Cod liver oil naturally contains vitamin A (retinol) and vitamin D, which can be helpful for anyone with these vitamin deficiencies. These vitamins support immune health, vision, bone strength, and overall metabolic function.

However, this can also be a drawback if you’re already supplementing these nutrients separately. Vitamin A is fat-soluble and can accumulate in the body, meaning excessive intake from multiple supplements may increase the risk of toxicity.

Purity and Contaminants

Since cod liver oil comes from the liver (the organ responsible for filtering substances in the body) there can be greater concern about contaminants if the oil is not carefully purified. High-quality manufacturers use processes such as molecular distillation to remove heavy metals and environmental toxins.

Fish oil supplements are often sourced from small, cold-water fish, which tend to accumulate fewer contaminants.

Sourcing

Sourcing also differs between the two oils. Fish oil is commonly derived from smaller fish such as anchovies and sardines that sit lower on the food chain, meaning they generally contain lower levels of accumulated environmental pollutants.

Cod liver oil comes from larger fish like Atlantic cod. Larger fish live longer and can accumulate higher levels of environmental contaminants over time, which is why quality sourcing and purification are especially important for cod liver oil products.

Despite their differences, cod liver oil and omega-3 fish oil share many of the same core benefits and characteristics.

Both provide essential omega-3 fatty acids.
Both supplements contain the important omega-3s EPA and DHA, which play key roles in supporting cellular health, regulating inflammation, and maintaining healthy physiological function.

Both support heart, brain, and joint health.
Since EPA and DHA influence inflammatory pathways and cell membrane function, both oils can support cardiovascular health, cognitive performance, and joint comfort when consumed regularly.

Both are derived from fish.
While cod liver oil is extracted from the liver of the Atlantic cod and fish oil is typically sourced from fatty fish like anchovies and sardines, both supplements ultimately come from marine sources rich in omega-3 fatty acids.

Both come in similar supplement forms.
Cod liver oil and fish oil are widely available in softgel capsules or liquid form, making them easy to incorporate into a daily routine.

Both help regulate inflammation.
EPA and DHA help balance inflammatory signaling in the body, which is why both supplements are often used to support exercise recovery, joint health, and long-term cardiovascular wellness.

Both are fat-soluble nutrients.
Omega-3 fats are best absorbed when taken with a meal that contains dietary fat, which helps improve digestion and utilization in the body.

Both benefit from third-party testing.
Because fish-derived oils can vary in quality, it’s advisable to seek out reputable products that undergo independent third-party testing to verify their purity, potency, and absence of contaminants such as heavy metals.

Both omega-3 fish oil and cod liver oil are generally considered safe for most people when taken at recommended doses. However, like any supplement, they can have potential side effects, especially if taken in excessive amounts.

Omega-3 Fish Oil

Omega-3 fish oil supplements are typically well tolerated. The most common side effects are mild digestive issues such as a fishy aftertaste, burps, or stomach discomfort. These symptoms are often less common with high-quality, purified fish oil products.

At very high doses, omega-3 fatty acids may have a mild blood-thinning effect. Because of this, anyone taking anticoagulant medications or preparing for surgery should consult a healthcare provider before using high-dose fish oil supplements.

Cod Liver Oil

Cod liver oil carries many of the same omega-3–related side effects as fish oil, such as fishy burps or mild digestive discomfort. However, it has an additional consideration: its naturally high vitamin A content.

Vitamin A is a fat-soluble nutrient that accumulates in the body. Consuming excessive amounts over time can lead to Hypervitaminosis A, a condition associated with symptoms such as headaches, nausea, bone pain, and in severe cases, liver damage.

For this reason, people who already take multivitamins or separate vitamin A or vitamin D supplements should be cautious when adding cod liver oil. 

Special Considerations During Pregnancy

Pregnant women should be particularly careful with cod liver oil due to the risk of excessive vitamin A intake. High levels of preformed vitamin A have been linked to an increased risk of birth defects, which is why many healthcare providers recommend avoiding high-vitamin-A supplements during pregnancy unless specifically advised by a doctor.

In general, choosing appropriate doses and high-quality, tested products can help minimize the risk of side effects from both omega-3 fish oil and cod liver oil.

“I’ve been taking Momentous Omega-3 Fish Oil and honestly it’s been a great addition to my daily routine. The capsules are easy to take, don’t leave that nasty fishy aftertaste, and just feel like a clean, high-quality supplement you can trust. I also like knowing they put real effort into purity and third-party testing, which makes a difference when you’re consistent with something you take every day.

“I think what really stands out is how easy it is on the stomach compared to other fish oils I’ve tried. No weird after-feel, no discomfort, it's just simple and effective. If you’re looking for a solid omega-3 that doesn’t feel like a chore to take, this one’s been a win for me.”

-John.

“I have experienced a dramatic increase in my eye health since using Momentous Omega 3. There is no fishy taste or aftertaste. I have glaucoma and the pressure readings have dropped into the normal range. I believe Momentous Omega 3 has contributed to the improvement.”

-Gwen.

Can you take cod liver oil and omega-3 fish oil together?

Yes, you can take cod liver oil and omega-3 fish oil together, but it’s usually unnecessary for most people. Both supplements provide the omega-3 fatty acids EPA and DHA, so combining them may simply increase your total intake beyond what you need. The bigger concern is that cod liver oil also contains vitamin A and vitamin D, which can accumulate in the body. If you are already taking a multivitamin or separate vitamin A or D supplements, adding cod liver oil on top of fish oil could push you above safe intake levels. For most people, choosing one high-quality omega-3 supplement is the simpler approach.

Is cod liver oil or fish oil better for brain health?

For brain health specifically, omega-3 fish oil is often the better choice because it typically delivers higher amounts of DHA, the omega-3 fatty acid most closely associated with brain structure and cognitive function. DHA is a major structural component of brain tissue and plays a role in memory, focus, and long-term brain health. Cod liver oil can still support brain function because it contains DHA, but many fish oil supplements provide significantly higher EPA and DHA concentrations per serving, making them a better option for cognitive support.

Is cod liver oil safe to take every day?

Cod liver oil can be safe to take every day when consumed in moderate amounts that stay within recommended vitamin A and vitamin D limits. The key consideration is that cod liver oil naturally contains preformed vitamin A, a fat-soluble nutrient that can build up in the body over time. Taking large doses or combining cod liver oil with other supplements containing vitamin A may increase the risk of excessive intake. People who already take multivitamins or vitamin A supplements should review their total intake before using cod liver oil daily.

How much EPA and DHA should you take daily?

Most general health guidelines suggest consuming 250–500 mg of combined EPA and DHA per day for basic cardiovascular and overall health. However, higher amounts—often 1,000 mg or more per day—are commonly used in research and clinical settings to support heart health, inflammation balance, and exercise recovery. Individual needs can vary based on diet, health goals, and medical history, so people considering higher-dose omega-3 supplementation should consult a healthcare professional.