Krill Oil vs Cod Liver Oil – Which Fish Oil Is Better?

Krill oil and cod liver oil are two popular fish oils people like to use. For this reason many people wonder which one is better. Let’s answer, krill oil vs cod liver oil, which is better?

Both oils are beneficial but krill oil provides more omega-3 fatty acids. It provides 3.50 grams of omega-3 per tablespoon, cod liver oil provides 0.84 grams. If vitamins A and D are more desired then cod liver oil is better due to its higher percentage of vitamins.

This article will take a closer look at the two oils and compare their nutrients, costs, benefits, mercury levels and side effects.

As a Certified Health Coach, many of my clients ask about fish oils. In addition to coaching clients about them, I’ve purchased, researched and consumed both prior to and after writing this article.

Disclaimer: Some links in this article are affiliate links which means I may earn a small commission at no extra cost to you. As an Amazon associate I earn from qualifying purchases. Always check with your physician prior to taking supplements or changing your nutrition habits.

Cod liver oil on the left and krill oil on the right.
Cod liver oil on the left and krill oil on the right

The Difference Between Krill Oil and Cod Liver Oil

Many people wonder if there is a difference between the two. Let’s take a closer look at both and examine their differences.

Krill oil is extracted from Antarctic krill and cod liver oil is extracted from the livers of cod fish. Krill oil contains the omega-3 fatty acids DHA and EPA, and phospholipid-derived fatty acids. Cod liver oil contains omega-3 fatty acids and vitamins A and D.

What is Krill Oil?

Krill oil is extracted from Antarctic Krill and is commonly used as a dietary supplement. It provides the omega-3 fatty acids eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and phospholipid-derived acid.

Many people are familiar with the other oils. Krill are less known to most people1. Therefore let’s take a look at what it is. Krill is a shrimp-like crustacean found in the oceans all over the world.

Other common crustaceans include shrimp, lobster, crabs, barnacles and more. What makes it unique from other fish oils is their phospholipid-derived fatty acid. Combined with omega-3, studies have shown omega-3s are absorbed more2.

krill oil
Krill oil soft gels

What is Cod Liver Oil?

Cod liver oil is oil extracted from the livers of codfish. It is used as a dietary supplement and provides the omega-3 fatty acids eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), vitamins A and D.

A tablespoon of cod liver oil contains 4,080 mcg of vitamin A, 34 mcg (1,360 IU) of vitamin D and 0.84 grams of omega-3 fatty acid3. What makes cod liver oils unique from other fish oils is their vitamins A and D.

Nutrition Comparison: Cod Liver and Krill

The following table compares all the nutrients:

Nutrient Cod Liver Oil (1 Tbsp) Krill Oil (1 Tbsp)
Calories 41 122
Omega-3 0.84 g 3.50 g
Total Fat 4.5 g 13.6 g
Saturated Fat 1.0 g 3.0 g
Cholesterol 25 mg 21 mg

Nutrient sources45

When comparing the nutrients above there is a large difference between the two. Krill contains approximately 420% more omega-3 fatty acids than cod liver oils. In addition, it contains phospholipid-derived fatty acids.

Studies have shown by combining omega-3 with phospholipid-derived fatty acids may increase the absorption of the omega-3s. Krill oil also contains astaxanthin, a keto-carotenoid which is responsible for its color6.

Cod liver oils contain less calories, total fat, saturated fat and cholesterol. This is due to its less amount of healthy fats typically obtained from oily fish flesh. They also contain more vitamins A and D . If you’re receiving omega-3s from an oily fish, cod liver oils may provide more benefits.

They are both known for being a part of many diets like keto or heart healthy.

If you’re eating low-carb or want to give keto a try, many of my clients have followed this 28-Day Keto Challenge with great success. Visit their website and check it out.

The Health Coach compares krill oil and cod liver oil.


Deciding on which oil to consume may involve more than determining whether benefits, vitamins or omega-3s are more important. With the rising costs of almost everything in the supermarkets, the cost is a likely factor.

Therefore, let’s take a closer look and compare their prices.

Krill oil costs more than cod liver oil. The average cod liver oil price is $18.97 per 180 softgels and krill oil is $107.97 per 180 softgels.

To conduct some original research, I visited the following two stores and compared the prices of each and found the following results.


  • Krill oil – NOW Brand (1,000 mg, 60 Softgels)
    • $35.99
  • Cod Liver Oil – NOW Brand (1,000 mg, 180 Softgels)
    • $18.37


  • Krill Oil – Kirkland Brand (500 mg, 160 Softgels)
    • $24.99
  • Cod Liver Oil – NOW Brand (1,000 mg, 180 Softgels)
    • $22.99

Both are easy to locate. I typically can find more affordable prices and availability on Amazon, Check them on Amazon and the current prices here.

cod liver oil softgels
Cod liver oil softgels

Mercury Levels

The FDA and EPA have issued warnings and suggestions regarding mercury levels in seafood and how often they should be consumed7. This is especially important for the following:

  • Developing children
  • Young infants
  • Pregnant women

They established a list of the following:

  • Fish to avoid
  • Good choices
  • Best fish

Therefore, let’s compare them and find out which one contains more mercury?

Cod liver oil and krill oil have similar levels of mercury. Cod fish and small crustaceans like krill are listed on the FDA’s best choices of fish regarding mercury levels. 

If you’re pregnant, breast feeding or has a young child, Always check with a physician prior to eating new foods or changing your dietary habits.

Mercury warnings can change over time or affect only a particular area or state. Please check with your local EPA and FDA for the current recommendations8.

Keto Bread Tip: Great News! Did you know, you don’t have to give up your favorite bread, pizza or sandwiches to follow a 100% Keto diet. Find out more in the KetoBreads website by clicking here, Keto Breads.

I recently completed an article comparing different fish oil. Find out which costs more or had more mercury among.

How To Determine The Correct Amount of Krill Oil and Cod Liver Oil

There’s no official recommendation for how much DHA and EPA omega-3 to take every day. Therefore, to determine how much DHA and EPA Omega-3 fatty acids to take:

  • Confer with a physician first.
  • Compare the dosage on a supplement bottle to the amount provided in a serving of whole fish.
  • Read the recommendations on the oil supplement bottle.

Additional tips:

  • Determine if the omega-3 fatty acids or Vitamins A and D are more important for you.
  • If omega-3 is more important the krill oil provides more.
  • If Vitamins A and D are more important, the cod liver oil may provide more benefits for you.
  • Don’t take krill oil and cod liver oil supplements together.
  • Take either one with food to aid digestion and absorption.
  • Never discontinue medication for a fish oil supplement without conferring with a physician first.

Health Benefits of Fish Oil

The omega-3 fatty acids help provide the many benefits listed below including heart disease. Fatty acids are not made by the body which is why many medical professionals and nutritionists recommend adding omega-3 sources to the diet.

Sources of omega-3 fatty acids include:

  • Fish (seafood)
  • Fish oil supplements
  • Seeds

The three common omega-3 fatty acids often referred to include:

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

DHA and EPA are mainly found in seafood and ALA is found in plant based foods like seeds. ALA converts to DHA and EPA but the conversion rate is very low. Therefore, it’s best to consume DHA and EPA to receive the optimal benefits9.

Find out how omega-3 compared in my recent article.

The health benefits of each oil include the following:

The hospital dietitian explains the health benefits of cod liver oil.

Fish Oil and Liver Oils: Heart Health

Heart health is crucial and both of them may help keep the heart healthy by preventing the following:

  • High blood pressure
  • High cholesterol
  • Heart attacks
  • Stroke
  • Heart disease

The fish oil helps to accomplish this by the following:

  • Lowering bad cholesterol and increasing good cholesterol.
  • Lowering blood pressure.
  • Lowering the fat cells in the blood (triglycerides).
  • Improving blood vessel function.

A study released in 2015 involved 47 people who supplemented with krill oil for four weeks. The results found it improved the health of blood vessels and insulin resistance more than olive oil. After 17 weeks, it also improved good cholesterol10.

Addition research examined over 34 previous studies which included 1,356 people. It was found the omega-3s in fish oil lowered both systolic and diastolic blood pressure. The researchers found a larger reduction in people with high blood pressure. This is important for heart health and preventing heart disease11.

Inflammation and Arthritis

Both have been shown to have anti-inflammatory health benefits. For this reason, taking fish oil supplements has been known to help prevent inflammation-related diseases like arthritis, diabetes and some cancers12.

Fatty Acid and Blood Circulation

Omega-3 fatty acids are later converted into other helpful molecules. For this reason, researchers believe they help keep a body’s blood vessels strong, capable and flexible. This allows for better blood flow and improved circulation of oxygen for better health13.

Cognitive Issues

The Omega-3 provided can help build up and maintain brain cells. Brain cells are constantly developed and repaired by fatty acids maintaining health. This can decrease the chance of cognitive degenerative diseases like Parkinson’s or Alzheimer’s14.

Eye Health and Improved Vision

Due to their omega-3s, they can help prevent retina deterioration. If the intraocular pressure (the fluid pressure in the eye or IOP) is greater than the normal range of 12-22 mm/Hg, glaucoma could occur or will at least be a considerable risk.

With a diet rich in omega-3 fatty acids, eye health may be helped. They help keep that IOP at a healthy level. This is another fantastic reason to take fish oil supplements15.

The doctor explains the health benefits of krill oil.

Krill Oil Dangers and Cod Liver Oil Side Effects

Both are considered safe, but there are some minor side effects. Therefore, a physician should be consulted prior to taking any fish oil supplement. Krill oil and cod Liver oil possible side effects include the following:

Oil and Bad Breath/Body Odor

The oils in the fish oil supplements can linger a while. This can result in bad breath lasting longer than is comfortable. This is more so when taking the liquid form of the supplement.

The fish oil supplements are made from pungent oils. Therefore, the fishy “grease” can stay in your system for quite some time and possibly increase the amount you sweat (but this does not happen often).


Stomach cramps and digestive health issues have been reported in rare cases. In addition, some people have experienced heartburn and loose stool in response to the upset stomach.

Always proceed with caution and don’t take too much at a time. Following your physician’s recommendation, reading labels and suggested measurements carefully are beneficial with or without side effects.


Allergies exist for many things including shellfish. Although having a shellfish allergy doesn’t automatically disqualify someone from taking fish oil, there may have been cross-contamination in the making and manufacturing process.

Labels and medical professionals could elaborate further on any additional inquiries.

Cod liver oil capsules.
Cod liver oil capsules

Oil and Bleeding

In rare cases, fish oil supplements have been known to cause nose bleeds and “easy bleeding.” This means if you get a cut, the bleeding might have a hard time stopping. Although this is rare, it can be dangerous to your health.

If this or any other concerns come up, it might be best to stop taking the supplements and speak to a physician.

Unhealthy levels of Vitamin A and D

More so with cod liver oil, unhealthy levels of both vitamins may exist. This is especially so if taking more than the recommended dosage of the supplement. Although this is often debated, it’s good to be aware of this and discuss it with a doctor.

In addition, fish oil may cause:

  • Nausea
  • Rash
  • Reduced vitamin E levels
  • Negative reactions with certain medications

Read Next Additional Fish Oil vs Fish Oil Articles!

Salmon Oil vs Fish Oil: Which Is Better?

  1. Wikipedia: Krill []
  2. Wikipedia: Krill oil []
  3. Wikipedia: Cod-liver oil []
  4. Nutrition Value: Fish oil, cod liver []
  5. National Center for Biotechnology Information: Krill for human consumption: nutritional value and potential health benefits []
  6. Wikipedia: Astaxanthin []
  7. FDA: Advice about Eating Fish []
  8. National Center for Biotechnology Information: Mercury accumulation in largemouth bass (Micropterus salmoides) in a Florida lake []
  9. National Institutes of Health: Omega-3 Fatty Acids []
  10. National Center for Biotechnology Information: Effects of krill oil on endothelial function and other cardiovascular risk factors in participants with type 2 diabetes, a randomized controlled trial []
  11. Circulation: Does fish oil lower blood pressure? A meta-analysis of controlled trials []
  12. National Center for Biotechnology Information: Cod liver oil (n-3 fatty acids) as an non-steroidal anti-inflammatory drug sparing agent in rheumatoid arthritis []
  13. National Center for Biotechnology: Marine Omega-3 Supplementation and Cardiovascular Disease []
  14. National Institute of Health: Omega-3 Fatty Acids []
  15. National Center for Biotechnology Information: Cod liver oil: a potential protective supplement for human glaucoma []

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