What's the difference between cod liver oil and fish oil capsules?

November 27, 2025 •

3 min read

According to research from the National Institutes of Health, omega-3 fatty acid supplements are among the most commonly used dietary supplements in the United States. But what's the difference between cod liver oil and fish oil capsules, and which one is the right choice for your health goals? This article breaks down the key distinctions between these popular supplements to help you decide.

Quick Summary

Cod liver oil is extracted from cod livers and is rich in omega-3s plus vitamins A and D. Fish oil comes from the flesh of various fatty fish and offers a higher concentration of omega-3s, typically without added vitamins.

Key Points

Source Difference: Cod liver oil comes from cod livers and contains omega-3s, plus vitamins A and D, while fish oil is from the flesh of various fatty fish and has higher omega-3s but no added vitamins.
Nutrient Profile: Cod liver oil provides vitamins A and D for immune support and bone health, whereas fish oil delivers a more concentrated dose of EPA and DHA for heart and brain health.
Vitamin A Toxicity Risk: Due to its high vitamin A content, excessive intake of cod liver oil can be toxic, so following dosage guidelines is crucial, especially for pregnant women.
Targeted Benefits: Choose cod liver oil for combined support for immunity, vision, and bones, and opt for fish oil if your main goal is boosting cardiovascular and brain health through a higher omega-3 dosage.
Do Not Combine: It is not recommended to take cod liver oil and fish oil together, as this may lead to an unsafe overconsumption of omega-3 fatty acids.
Consult a Doctor: Always talk to a healthcare professional before starting either supplement, especially if you have pre-existing medical conditions or are on other medications.

Understanding the Source and Composition

While both cod liver oil and fish oil are sources of beneficial omega-3 fatty acids, their primary difference lies in their origin and nutrient composition.

Cod Liver Oil

Cod liver oil is extracted from the liver of codfish. This source provides omega-3s along with significant amounts of vitamins A and D, naturally stored in the liver. It's often chosen for boosting these vitamins, especially in areas with limited sunlight.

Fish Oil

Fish oil is derived from the fatty tissues of various oily fish like mackerel, salmon, and anchovies. The extraction yields a product with a higher concentration of EPA and DHA omega-3 fatty acids compared to cod liver oil, and generally doesn't contain vitamins A and D unless added.

Comparison: Cod Liver Oil vs. Fish Oil Capsules


Feature	Cod Liver Oil Capsules	Fish Oil Capsules
Source	Liver of codfish only	Flesh of oily fish (salmon, mackerel, anchovies)
Omega-3 Content	Good source, but often lower than fish oil	Generally higher concentration of EPA and DHA
Vitamin A & D	Rich, naturally occurring source	Contains little to no vitamins unless fortified
Primary Benefit Profile	Eye health, bone health, immune support	Cardiovascular health, brain function, anti-inflammatory
Risk of Toxicity	Risk of vitamin A toxicity with excessive dosing	Generally low risk of vitamin toxicity
Best For	Individuals needing vitamins A & D, especially in winter or with bone/eye concerns	Individuals prioritizing high omega-3 intake for heart and brain health

The Unique Benefits of Each Supplement

Choosing depends on your nutritional needs. Both provide anti-inflammatory benefits from omega-3s, but their compositions lead to different strengths.

The Advantages of Cod Liver Oil

Cod liver oil's vitamins A and D offer specific benefits, including support for the immune system, bone health, and eye health. It may also help with joint pain and stiffness.

The Advantages of Fish Oil

Fish oil's higher omega-3 concentration makes it ideal for maximizing EPA and DHA benefits: it supports heart health by helping reduce triglycerides and may improve brain function. Its higher omega-3 dose can also be more effective for reducing inflammation.

Considerations and Precautions

Both are generally safe, but dosage is important. Excessive cod liver oil can lead to vitamin A and D toxicity. Pregnant or breastfeeding women should be cautious about vitamin A intake and consult a doctor.

Both oils can thin blood. Consult your doctor before taking either if you use blood thinners or have surgery scheduled. A doctor can help determine suitability and dosage. Avoid taking both oils together to prevent excessive omega-3 intake.

Conclusion: Making the Right Choice

Deciding requires understanding your health needs. Cod liver oil is ideal if you need omega-3s plus vitamins A and D for immune, eye, and bone support, especially with limited sun exposure. Fish oil is better if your priority is a high omega-3 dose for heart and brain health without added vitamins. Always consult a healthcare professional for safe and effective use. For more comprehensive information on omega-3 fatty acids, visit {Link: NIH https://ods.od.nih.gov/factsheets/Omega3FattyAcids-Consumer/}.

Choose reputable brands with third-party testing for purity.

Frequently Asked Questions

It is not recommended to take both cod liver oil and fish oil capsules at the same time. Combining them could result in an excessive intake of omega-3s. Additionally, cod liver oil contains vitamins A and D, and taking too much can lead to vitamin toxicity.

For joint pain, both oils offer anti-inflammatory benefits from their omega-3 content. Cod liver oil's combination of omega-3s and vitamin D may be more targeted for joint health and inflammation, with some studies showing reduced pain in individuals with rheumatoid arthritis.

Fish oil is often considered better for heart health due to its typically higher concentration of EPA and DHA, the key omega-3s for cardiovascular benefits. These fatty acids help lower triglycerides and improve other heart health markers.

Yes, cod liver oil carries a risk of vitamin A toxicity if taken in high doses over time. It can also have blood-thinning effects and may interact with certain medications.

Cod liver oil is often preferred for immune support due to its natural content of vitamins A and D. These vitamins, along with the omega-3s, provide antioxidant and anti-inflammatory support beneficial for a healthy immune system.

The best choice depends on your specific needs. If you need extra vitamins A and D for bone or eye health, particularly if you have limited sun exposure, choose cod liver oil. If your main goal is a high dose of omega-3s for heart or brain health, fish oil is the better option.

Some side effects like mild gastrointestinal upset, burping, or a fishy aftertaste can occur with both. However, cod liver oil has the additional risk of vitamin A toxicity with overconsumption, a risk not associated with standard fish oil.