Cod liver oil: properties, benefits and contraindications

It is not just a natural supplement: it is a true time capsule that encapsulates the wisdom and nutritional science of centuries and centuries. Cod liver oil is such a valuable and multifaceted product that it deserves more than an in-depth study: it needs a guide.

Cultivate your curiosity, nourish your well-being with cod liver oil.

Cod liver oil: what it is and how it is obtained

It all starts with cod that swim freely in the depths of pure, cold waters. An oil rich in Omega-3, vitamin A and vitamin D is extracted from their liver. 

To ensure you get all the benefits dispensed by its nutrients, you should regularly consume raw cod liver. A food that, for obvious reasons, does not abound on our tables. Therefore, today it is available in the form of convenient dietary supplements that allow you to integrate wellness into your life more conveniently and regularly.

Cod liver oil and fish oil: the differences

There is often confusion: cod liver oil and fish oil are two different products. Yes, they are both valuable allies for your well-being since they are rich in Omega-3 fatty acids, but they are not interchangeable.

What makes the difference is, first of all, the raw material from which they are derived: the former is extracted from cod liver and the latter from fish muscle. And this aspect has a major impact on the nutritional profile: liver, in fact, is rich in vitamin A, while fish oil lacks it.

You should know that, in the past, prolonged intake of cod liver oil was not recommended. The reason? The old techniques of purifying the oil kept its composition almost intact, and the final product contained massive doses of vitamin A and vitamin D. Both vitamins are essential for well-being, of course, but they should not be taken in excess.

This is why cod liver oil intake was once recommended only in the winter months, to stock up on its active ingredients.

Today things have changed. Thanks to modern molecular purification techniques, we can offer you a product suitable for prolonged intake. How? By reducing the vitamin A content to levels optimal for your well-being. But that's not all: state-of-the-art treatments allow us to purify the oil of contaminants and other unwanted components and then add the most valuable molecules (such as vitamins) in the desired dosages.

Cod liver oil: nutritional values

If we take a closer look at what cod liver oil contains, we find that inside it we find not only Omega-3s and vitamins.

In 100 g of cod liver oil there are about:

• 22.6 g saturated fat;
• 46.7 g monounsaturated fat;
• 22.5 g of polyunsaturated fats, among them Omega-3 EPA (eicosapentaenoic acid, 6.9 g) and DHA (docosahexaenoic acid, 11 g);
• 30 mg vitamin A;
• Vitamin D (250 micrograms);
• Trace minerals (sodium, potassium and iron).

Since it is a fatty substance (with an intake of 900 calories per 100 g), cod liver oil facilitates the assimilation of vitamins A and D, both of which are fat-soluble. 

But now let's take an even more detailed look at each of the substances contained in a drop of cod liver oil. Let's start with.

Omega-3 fatty acids: ALA, EPA and DHA

Among the active ingredients in cod liver oil are Omega-3s, fatty acids associated with more than one beneficial effect recognized by EFSA, the European Food Safety Authority:

• protect the heart and help control hypertension (EPA and DHA);
• keep triglyceride (EPA and DHA) and cholesterol (ALA) levels in the blood under control;
• Promote brain and retinal development and health (DHA).

And not only that. The scientific literature associates Omega 3:

• an antithrombotic (with reduced risk of heart attacks and strokes) and antiarrhythmic action;
• The increase in "good" HDL cholesterol;
• an anti-inflammatory action that is useful in combating intestinal diseases and other inflammation-related conditions;
• The regulation the immune response;
• The control of cell proliferation, a useful action against tumors;
• the ability to prevent age-related macular degeneration, a major cause of blindness in old age;
• The reduction of symptoms of some neurological and psychiatric diseases.

Nourishing our bodies with Omega-3 is therefore essential at every stage of life. Unfortunately, however, while in great need of them, our bodies are unable to synthesize alpha-linolenic acid (ALA), the precursor to the Omega-3s EPA and DHA known for their beneficial effects on health, on their own.

In addition, the conversion of alpha-linolenic acid to EPA, which is then converted to DHA, is not efficient: only 5% of ALA is converted to EPA and less than 0.1% is converted to DHA. 

That is why not only ALA but also EPA and DHA are considered "essential" nutrients, i.e., to be taken with food. And that is why, from a nutritional point of view, the best strategy is not to take ALA, but EPA and DHA "ready to use."

But where are these valuable nutrients found? Fish such as salmon, mackerel, and herring are among the best dietary sources of EPA and DHA. Of course, it's not easy to get them into the diet to an extent that meets our needs--but that's precisely why dietary supplements exist!

All the vitamins contained in cod liver oil

Cod liver oil is a natural source of vitamin A. According to EFSA, this vitamin:

• Helps metabolize iron;
• Promotes the proper functioning of the immune system;
• Helps maintain healthy skin (fighting wrinkles) and mucous membranes;
• Keeps teeth healthy;
• promotes healthy vision (vitamin A deficiencies can impair visual abilities).

In addition to cod liver oil, this valuable vitamin is also found in dairy products, poultry, red meat, and fish. And it can be taken in the form of beta-carotene (the pro-vitamin A), a precursor of it that abounds in carrots, apricots, and several other fruits or vegetables (such as broccoli, spinach, and most vegetables with dark green leaves).

Cod liver oil also contains the valuable vitamin D, which boasts numerous EFSA-recognized benefits.

This vitamin:

• helps absorb and use calcium and phosphorus;
• promotes healthy bones and teeth (in fact, its deficiency can cause growth retardation, rickets, development of curved legs, and protruding abdomen in children; while in adults it can cause brittle bones, contractions, and muscle spasms);
• Promotes good functioning of the muscles and immune system.

To get your fill of vitamin D, as you may already know, it is good to expose your skin to sunlight: UVB rays allow cholesterol to be used to produce vitamin D. Its food sources, on the other hand, are very scarce (we find it in chicken egg yolk and yellowfin tuna), so cod liver oil products become a valuable ally.

How is cod liver oil used?

It appears that cod liver was fermented as early as the 1700s, and the use of the oil for medicinal purposes dates back to at least the 19th century, when it was used in the treatment of rickets. Today it is on the market in the form of dietary supplements used for a great many purposes.

Some people, for example, use cod liver oil as a restorative or to maintain healthy skin and hair. Some take it to lower cholesterol and triglycerides, some to combat kidney problems associated with diabetes, or against high blood pressure, cardiovascular disease, osteoarthritis, depression, systemic lupus erythematosus, glaucoma, otitis... And there is no shortage of those who apply it directly to the skin to speed up wound healing. 

In short: its benefits cannot be counted. 

The benefits of cod liver oil: what it is used for and when to take it

As you already know, there are indeed many applications of cod liver oil. Let's focus on the proven benefits.

Cod liver oil supplements can be helpful in promoting good functioning of the heart, brain and eyesight and in lowering triglyceride levels in the blood. These fats, if in excess, are very dangerous to health, as they increase the risk of coronary artery disease (a disease of the coronary arteries that supply the heart). Well, cod liver oil can help reduce them by up to 50 percent.

In addition, it is a valuable ally in moderate hypertension, as it promotes a slight but significant reduction. Keeping blood pressure under control is important to protect the health of the heart and blood vessels. In fact, hypertension can damage the inner lining tissue of the arteries, promoting the formation of cholesterol buildup (atherosclerotic plaques) and, thus, atherosclerosis, a condition that leads to narrowing of the arteries resulting in increased pressure. A real vicious cycle is thus established that can cause problems such as arrhythmias, heart attacks and strokes. 

In addition to these certified uses, cod liver oil also appears to be useful in combating kidney problems associated with type 2 diabetes. The evidence? Its intake corresponds to a reduction in the level of protein in the urine, a marker of the severity of kidney disease. 

Over the years, this valuable oil has also been recommended for the treatment of depression, heartbeat irregularities associated with cardiovascular disease, pediatric ear infections, systemic lupus erythematosus (an autoimmune disease affecting various organs), and various other health problems. 

For the time being, however, there is a lack of scientific evidence guaranteeing the efficacy of using cod liver oil for all these latter purposes.[1] In short, despite its many years of use, we are not yet finished discovering the secrets of this complex elixir!

Cod liver oil for dogs, cats and horses

Did you know that cod liver oil is also a panacea for the well-being of our four-legged friends?

It appears, for example, to help dogs grow healthy and strong; in fact, it is used during pregnancy, to address vitamin deficiencies, as a restorative, and to promote healthy skin and hair after trauma.

In cats, on the other hand, it is recommended to make up for vitamin A deficiencies that could impair vision, as well as to promote healthy skin and fur. Not only that, there are also those who recommend its administration to fight inflammation, promote heart and immune system health, strengthen bones, promote good functioning of the nervous system, muscles, and to fight cancer.

It is also used on horses to protect eyesight, bones, hair and hooves. It also appears to help fight lung disease, promote growth and increase energy.

We told you ahead of time: the benefits of cod liver oil are truly amazing!

How to choose a quality cod liver oil supplement

After reviewing all the benefits, we come to the more practical information. How to.

What kind of supplement to buy? You will find different cod liver oil products on the market, in different formulations. You can buy it, for example, in the form of capsules (hard or soft), pearls, softgels, opercula containing an oily concentrate, in liquid form, or as a syrup suitable for children. 

Where to buy it. In herbalists, pharmacies, parapharmacies or you can also buy it online. The important thing is to rely on safe channels of Promo . 

How to tell if the supplement is quality? We recommend that you choose-or rather, demand-a product of pharmaceutical grade, that is, one that meets standards suitable for medicinal use. You will find that the price of supplements varies widely: next to products that cost less than 5 euros you will find others that cost 50 euros. So how to orient yourself?

To select a quality product, read the label very carefully. The first thing to evaluate is the EPA and DHA content per capsule (not per package): multiply it by the number of capsules to trace the total EPA+DHA content of the package. If you divide the package price by the total content you will be able to trace the price per 1,000 mg of Omega-3. Then compare this price with that of other products, so you will be able to locate the cheapest one.

How to take cod liver oil: dosages

Each supplement is a planet unto itself. Therefore, the dosage depends on the product purchased.

The first factor that determines dosage is the concentration of the active ingredients: the number of capsules taken in a day depends on their EPA and DHA content. How many are needed to arrive at the required dosage? The higher the concentration of the product, the fewer capsules taken.

In addition, the dosage also depends on the reason for taking cod liver oil supplements. The scientific literature tells us, for example, that to reduce triglyceride levels and to lower blood pressure it is necessary to take 20 ml of cod liver oil daily. On the other hand, if cod liver oil is taken against high cholesterol, doses should be up to 30 ml per day.

However, we would like to remind you that these dosages are only indicative: the dosage depends on the age of the person taking the supplement and the particular needs of each person.

EFSA, for its part, reminds us that:

• 250 mg EPA+DHA daily is needed to promote good heart function;
• 250 mg of DHA per day is needed to promote good brain and vision function;
• 2 grams per day of DHA, taken in combination with some EPA, or, more simply, 2 grams per day of EPA+DHA are needed to keep triglycerides in the normal range;
• 3 grams per day of EPA+DHA are needed to maintain normal blood pressure.
  
  

The side effects of cod liver oil

Good news: cod liver oil is a safe remedy for most people in good health.

There are, however, some possible side effects, such as belching, bad breath, heartburn, and nosebleeds-all of which can be alleviated or avoided by taking the supplement at mealtimes. The problem related to the taste of cod liver oil, which can be unpleasant, can instead be solved by choosing operculum or capsule formulations, or by opting for a flavored product.

Indeed, even classic cod liver oil to be taken by the spoonful, if obtained through careful purification processes and properly flavored, can taste surprisingly pleasant! Such is the case with Omegor® Classic, which precisely because of this characteristic won the Superior Taste Award, given by the International Taste Institute based on the evaluation of a jury of internationally renowned chefs and sommeliers.

In any case, it is important to take cod liver oil by following a proper dosage, the one recommended by your doctor, nutritionist or pharmacist: too high doses of the supplement can in fact cause nausea and soft stools, or hinder blood clotting by increasing the risk of bleeding. 

In addition, it is good to remember that the vitamins A and D in the supplement, if taken in excess, can also have side effects. Which ones?

Too much vitamin A can cause such ailments as nausea, vomiting, loss of appetite, skin problems, fatigue and drowsiness, dizziness, severe headaches, pain in the stomach, behind the eyes, bones, or joints, changes in the menstrual cycle, vision problems, growth retardation, hair loss, and jaundice.

Excess vitamin D, on the other hand, can cause increases in blood calcium levels that can in turn trigger nausea or vomiting, reduce appetite, and promote calcium accumulation in soft tissues (for example, in heart or lung tissue). Side effects related to excess vitamin D also include weakness, weight loss, confusion and disorientation, frequent urination, and kidney problems.

Cod liver oil contraindications.

More than contraindications, let's talk about interactions. In fact, cod liver oil can interact with some medications, dietary supplements, or herbal products by affecting blood pressure and blood clotting. Find everything in this table.

Table 1  

We would also like to remind you that not enough information has been gathered to ensure the safety of taking cod liver oil during pregnancy or breastfeeding. In such cases, it is even more important to seek advice from your doctor. Keep in mind, too, that per se, during pregnancy, taking vitamin A (also present, as we mentioned, in cod liver oil) is contraindicated. 

We are here to make, together, a difference in your life.

Bibliographic references: 

Averna MR et Al. Omega 3 and cardiovascular risk reduction. PPG Scientific Editions, 2003

Baker EJ et Al. Metabolism and functional effects of plant-derived omega-3 fatty acids in humans. Prog Lipid Res. 2016 Oct;64:30-56. doi: 10.1016/j.plipres.2016.07.002

Berbert AA, Kondo CR, Almendra CL, Matsuo T, Dichi I. Supplementation of fish oil and olive oil in patients with rheumatoid arthritis. Nutrition. 2005 Feb;21(2):131-6. doi: 10.1016/j.nut.2004.03.023

Bourre JM. Roles of unsaturated fatty acids (especially omega-3 fatty acids) in the brain at various ages and during aging. J Nutr Health Aging. 2004;8(3):163-74. PMID: 15129302

European Commission. Food and Feed Information Portal Database. Last viewed: 07/02/25

Conklin SM, Harris JI, Manuck SB, Yao JK, Hibbeln JR, Muldoon MF. Serum omega-3 fatty acids are associated with variation in mood, personality and behavior in hypercholesterolemic community volunteers. Psychiatry Res. 2007 Jul 30;152(1):1-10. doi: 10.1016/j.psychres.2006.10.006

Create. FoodsNUTrition. Food composition tables. Cod liver oil. Last viewed: 07/02/25

Drugs.com. Vitamin A 

Fontani G, Corradeschi F, Felici A, Alfatti F, Migliorini S, Lodi L. Cognitive and physiological effects of omega-3 polyunsaturated fatty acid supplementation in healthy subjects. Eur J Clin Invest. 2005 Nov;35(11):691-9. doi: 10.1111/j.1365-2362.2005.01570.x 

Germano M, Meleleo D, Montorfano G, Adorni L, Negroni M, Berra B, Rizzo AM. Plasma, red blood cells phospholipids and clinical evaluation after long chain omega-3 supplementation in children with attention deficit hyperactivity disorder (ADHD). Nutr Neurosci. 2007 Feb-Apr;10(1-2):1-9. doi: 10.1080/10284150601153801

Grimble RF, Tappia PS. Modulation of pro-inflammatory cytokine biology by unsaturated fatty acids. Z Ernahrungswiss. 1998;37 Suppl 1:57-65. PMID: 9558730

Harris WS. Achieving optimal n-3 fatty acid status: the vegetarian's challenge...or not. Am J Clin Nutr. 2014 Jul;100 Suppl 1:449S-52S. doi: 10.3945/ajcn.113.071324

Hussein N, Ah-Sing E, Wilkinson P, Leach C, Griffin BA, Millward DJ. Long-chain conversion of [13C]linoleic acid and alpha-linolenic acid in response to marked changes in their dietary intake in men. J Lipid Res. 2005 Feb;46(2):269-80. doi: 10.1194/jlr.M400225-JLR200

IFOS - The international fish oil standards program 

Johnson EJ, Chung HY, Caldarella SM, Snodderly DM. The influence of supplemental lutein and docosahexaenoic acid on serum, lipoproteins, and macular pigmentation. Am J Clin Nutr. 2008 May;87(5):1521-9. doi: 10.1093/ajcn/87.5.1521

Lauritzen L, Jørgensen MH, Mikkelsen TB, Skovgaard lM, Straarup EM, Olsen SF, Høy CE, Michaelsen KF. Maternal fish oil supplementation in lactation: effect on visual acuity and n-3 fatty acid content of infant erythrocytes. Lipids. 2004 Mar;39(3):195-206. doi: 10.1007/s11745-004-1220-8

Mayo Clinic. Nutrition and healthy eating. What is vitamin D toxicity, and should I worry about it since I take supplements? 

MedlinePlus. Cod Liver Oil 

MedlinePlus. Vitamin A 

MedlinePlus. Vitamin D 

MedlinePlus. Vitamin D Deficiency

Miller PE et Al. Long-chain omega-3 fatty acids eicosapentaenoic acid and docosahexaenoic acid and blood pressure: a meta-analysis of randomized controlled trials. Am J Hypertens. 2014 Jul;27(7):885-96. doi: 10.1093/ajh/hpu024

Neuringer M, Reisbick S, Janowsky J. The role of n-3 fatty acids in visual and cognitive development: current evidence and methods of assessment. J Pediatr. 1994 Nov;125(5 Pt 2):S39-47. doi: 10.1016/s0022-3476(06)80735-3

Pawlosky RJ, Hibbeln JR, Novotny JA, Salem N Jr. Physiological compartmental analysis of alpha-linolenic acid metabolism in adult humans. J Lipid Res. 2001 Aug;42(8):1257-65. PMID: 11483627

Poli A. Omega-3 fatty acids and cardiovascular prevention. Trends in Medicine vol 2 num 3, PPG Scientific Editions, 2002 

Querques G, Souied EH. The role of omega-3 and micronutrients in age-related macular degeneration. Surv Ophthalmol. 2014 Sep-Oct;59(5):532-9. doi: 10.1016/j.survophthal.2014.01.001

Saldeen P, Saldeen T. Women and omega-3 fatty acids. Obstet Gynecol Surv. 2004 Oct;59(10):722-30; quiz 745-6. doi: 10.1097/01.ogx.0000140038.70473.96

USDA. National Nutrient Database for Standard Reference. 04589, Fish oil, cod liver. Last viewed: 07/02/25