10 Benefits of Cod Liver Oil

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10 Benefits of Cod Liver Oil:

The benefits of cod liver oil have been known for centuries.  Rickets was a common disease in 17th century England that was also rampant throughout the United States in the 1920s. When cod liver oil was used to eradicate the disease by the 1903s, scientists had only known that this marine based oil was an excellent source of vitamins A and D.   This was one of many benefits of cod liver oil.

Successfully used to treat nutrient deficiencies and disease for over 100 years, the strong therapeutic properties of many health benefits of cod liver oil continue to be revealed today.

Cod liver oil treats a variety of health conditions ranging from asthma, heart disease, arthritic and neurological conditions. This article will outline the top 10 benefits of cod liver oil and how supplementation can improve your quality of life.


Why Take Cod Liver Oil?

Cod liver is an excellent source of healthy omega-3 fatty acids, and vitamins A and D.  The regular practice of consuming cod liver daily in Nordic countries like Iceland and Norway is believed to result in reduced deficiencies in people living in these areas (2).

Cod liver oil is the number one choice of dietary vitamin D supplementation in these countries and is commonly used from the beginning of infancy and throughout life (25).

The combination of these nutrients provide antioxidant and anti-inflammatory properties that protect the body from illness and chronic diseases like cancer.  Here are the top 10 benefits of Cod liver oil.

1. Cod Liver Oil is a Great Source of Vitamin D:

Optimal vitamin D levels is key to supporting endless physiological processes within the human body. Vitamin D: (1)

  • Fortifies bone strength and muscle function
  • Aids in calcium absorption across the gut lining
  • Contributes to oral health
  • Protects against cancer
  • Improves body weight management

Lifestyle habits including increased time spent indoors, greater dependence on medications and drug use, and poor dietary habits are all causes for the epidemic of vitamin D deficiency in people today. Worldwide, vitamin D deficiency impacts approximately 1 billion people (4).

Cod liver oil is rich in vitamin D and is estimated to reduce the burden of chronic disease by no less than 10% by normalizing vitamin D levels (3). Vitamin D works synergistically with vitamin A which is also naturally occurring in cod liver oil. This combination of vitamins increases the biological effects of each including the ability to promote apoptosis in prostate cancer cells (5).

vitamin d deficiency, Vitamin D Deficiency: Common Symptoms and Solutions

2. Supports Bone Health:

Vitamin D is predominantly synthesized beneath the skin when exposed to UVB rays. When seasonal changes and fewer sunlight hours prevents the body from manufacturing adequate vitamin D3 levels, there is an increased risk for vitamin D deficiency and osteoporosis in post-menopausal women.

The vitamin D content in cod liver oil is more concentrated than any single other food source and can help improve bone density. In post-menopausal women, cod liver oil protects against bone mineral loss and reduces the risk of bone fractures. (6, 7, 9)  This is one of the very important benefits of cod liver oil.

Nutritional intake of vitamin D is also very important for athletes looking to recover from strength training and intense exercise. Dietary supplementation of cod liver oil to athletes may help maintain bone density especially when exerting themselves during intense physical training (10).

3. Reduces Cancer Risks:

Sun exposure remains the most important factor known to reduce the risk of breast cancer.  However, a Nurses’ Health Study found that vitamin D supplementation can also significantly reduce breast cancer risks. Evident at all stages of life, cod liver oil intake appears to have a direct correlation with the pro-apoptosis and anti-proliferative activities on breast cancer cells. (11)

A study of Norwegian women showed that daily supplementation of cod liver oil in individuals with tumors and lung cancer patients had the lowest risk of mortality. When taken annually, the benefits from cod liver oil were evident regardless of whether the patients had taken supplementation before diagnosis or as a form of treatment following. (12)

4. Contains Anti-Inflammatory Omega-3 Essential Fats:

Dietary patterns including high sugar intake, increased trans fat consumption from hydrogenated vegetable oils and the overabundance of processed foods fortified with synthetic nutrients devoid of real nutrition contribute to low omega-3 levels in Western diets today and thus promote the development of disease.

The problem with omega-3 deficiency specifically correlates with the increased amount of omega-6 fatty acids common in the Standard American Diet. A healthy ratio of 2:1 omega-6 fats to omega-3 fats is now approximately 16:1. This imbalance contributes to poor health and is characteristic of individuals with mood disorders like depression, insulin resistance, metabolic and hormonal disturbances. (14)

Among many vital functions, omega-3 fatty acids are essential for regulating metabolism, influencing inflammatory responses in the body, controlling insulin pathways in the brain, supporting cognitive health and reducing the risk of chronic degenerative diseases.

Omega-3 fats mediate anti-inflammatory reactions in the body. The two major omega-3 fatty acids in cod liver oil are EPA (eicosapentaenoic acid) and DHA (dochosahexaenoic acid). These fats reduce circulating antigens in the body that trigger autoimmune reactions and downregulate processes involved in the production of pro-inflammatory cytokines (14).

cod liver oil

5. Boosts Brain Health:

Studies involving newborns support that DHA is vital for the development of brain and emotional health and is especially important in premature infants (15).  Omega-3 fats inhibit the inflammatory responses that can cause metabolic alterations that are known triggers of Alzheimer’s disease, dementia, depression and abnormal hormone signaling in the hypothalamus region of the brain (16).

Increasing fatty acids can boost brain health by controlling insulin sensitivity in the brain to ward off obesity, type-2 diabetes and prevent cognitive decline (18). Research suggests that the two fatty acids found in cod liver oil (EPA and DHA) are likely to provide the greatest benefit at preventing and providing therapeutic treatment to those with bipolar depressive disorders (19).

6. Heart Disease Prevention:

Analysis of a large group survey of European individuals found that those who supplemented dietary cod liver oil reported fewer symptoms of cardiovascular disease and stroke (8).  Preventing heart disease is another one of the benefits of cod liver oil.

Omega-3 fatty acids in cod liver oil improve cholesterol levels, control high blood pressure and also reduces the risk for metabolic syndrome which can lead to cardiovascular disease. Cod liver oil may be just the right intervention for lowering the prevalence of metabolic syndrome which currently affects: (17)

  • 34% of Americans over the age of 20
  • 4% of adolescents

In clinical trials, patients with heart disease who supplemented marine sourced omega-3 fats had a lower risk of mortality and improved vascular function. Protective benefits of the cardiovascular system may underlie with the ability of EPA and DHA to improve glycemic control. (21)

cod liver oil

7. Treats Concerns Associated with Diabetes:

An imbalance of fatty acid levels is deleterious to health creating an environment of increased oxidative stress resulting from omega-3 deficiency in skeletal muscle fibers.  Low levels of omega 3 composition within muscle cells makes them extremely susceptible to stress.

This suggests that omega-3s in cod liver oil can improve skeletal muscle membranes and therefore better control insulin response and glucose concentration. (22)  This is another one of the major benefits of cod liver oil usage.

Cod liver oil supplementation may also help treat complications of poor insulin signaling and glucose levels in patients with diabetes. A 12 week study that analyzed metabolic markers in diabetic rats found that cod liver oil exhibited multiple benefits. These include: (23)

  • Protection from degenerating muscle tissue
  • Better tissue fluid regulation and mitochondrial performance
  • Reduced swelling in endothelial cells which consequently also reduced the risk for cardiovascular disease

A nationwide study conducted in Norway also found that the availability of vitamin D in cod liver oil was linked to a lower risk of type-1 diabetes. When mothers supplemented cod liver during pregnancy, the toddlers were significantly less likely to develop diabetes within their first year of life. (25).

omega 3, Top 8 Health Benefits of Omega 3 Fatty Acids

8. Improves Reproductive Health:

Fetal development is another one of the big benefits of cod liver oil.  Dietary intake of omega-3 fats during the last trimester of pregnancy and the initial months of a newborn’s life is crucial to the development of the central nervous system in fetus and child.

Children born to mothers who supplemented cod liver oil into their diets during pregnancy and continued throughout nursing exhibited higher scores on a standardized test (KABC) that assesses intelligence and achievement in preschoolers (24).

A global trend continuously on the rise is vitamin D deficiency and its association with infertility. Low concentrations of vitamin D have been shown to lower sperm count and quality. Deficiency also poses a higher risk for miscarriage because of disturbances created during the implantation process and loss of embryonic protection during the 1st trimester (26).

9. Cod Liver Oil Supplies Vitamin A:

Vitamin A is an important part of the human diet and is essential for health. Like vitamin D, vitamin A is required for the synthesis of hormones and is a key player in the function of the immune system. It is also fat-soluble, which is why the combination of fatty acids in cod liver oil enhances the delivery of vitamin A to the body.

As earlier noted, without vitamin D, vitamin A could not work effectively in the body and the inverse is also true. Much of the reason for the debate on the possible toxicity of vitamin A likely stems from the fact that the American diet is deficient in vitamin D.

Fortunately, one of the benefits of cod liver oil supplements that are high quality is that they contain an excellent and balanced source of both vitamin A and D. With good reason, Europeans have been supplementing cod liver oil in their diets for centuries. Vitamin A contains antioxidant properties and supports cellular growth and repair, aids in reproductive function in men and women, and is essential for bone health and night vision. (27)

Another one of the benefits of cod liver oil is that it is being used as a natural therapy to treat glaucoma. Vitamin A preserves vision by inhibiting oxidative trauma to the eyelids as well as the ocular lens which protect the cornea. Eye conditions like night blindness are reversible with increased vitamin A intake from cod liver oil and can slow the progression and severity of glaucoma. (28)

cod liver oil

10. Relieves Arthritic Pain and Swelling:

Studies show that marine sourced omega-3 fats like those from cod liver oil reduce the risk of developing rheumatoid arthritis and also alleviate symptoms in those suffering with the disease.  This is another of the great benefits of cod liver oil.

EPA and DHA both inhibit joint inflammation caused by a species of bacteria known to inflict systemic complications including arthritic flare-ups. A 3:1 ratio of omega-6 fats to omega-3 fats in people with rheumatoid arthritis had a significantly beneficial effect on suppressing inflammation. A 5:1 ratio improved other systemic inflammatory reactions (20). (13)

Clinical evidence supports that the benefits of cod liver oil supplementation can reduce the intake of NSAID (nonsteroidal anti-inflammatory drug) medication in these patients. Omega 3 fatty acids naturally suppress inflammation and swelling, reduce the duration of morning stiffness, decrease pain and severity of the disease and also improves joint strength. (14)

cod liver oil

Supplementing with Cod Liver Oil:

Understanding which cod liver oil is right for you can be intimidating with so many brands on the market. Many contain an assortment of synthetic ingredients including added dyes, artificial flavors, binders and preservatives which should be avoided.  Be sure to get one from a reputable brand.  My favorite is Nordic Naturals, which has the best reputation in the fish oil industry and 3rd party tests all their batches for purity.

Depending on the manufacturer, cod liver oil will contain varying concentrations of omega-3s and vitamins A and D.   A recommended guideline for supplementing cod liver oil into your diet is as follows:

  • Children ages 3 months – 12 years:  1 tsp regular potency formula. Dosage should provide 5,000 IU vitamin A and 500-1,000 IU vitamin D daily.
  • Children over 12 years & adults: 2 tsp regular potency formula. Dosage should provide 10,000 IU vitamin A and 1,000-2,000 IU vitamin D daily.
  • Pregnant & nursing women: 4 tsp regular potency formula. Dosage should provide 20,000 IU vitamin A and 2,000-4,000 IU vitamin D daily.

Be sure to read the label to understand the potency of the oil you are taking and adjust dosing accordingly so you can get the benefits of cod liver oil.

cod liver oil

Risks and Side Effects of Cod Liver Oil:

Taking cod liver oil is likely safe for most people. However, high dose supplementation can increase the risk for bleeding. If you experience nausea and/or loose stool, it may also be possible that your vitamin A and D levels are too high.

Common complaints that may occur include bad breath, belching, heartburn and nosebleeds. Consider taking your supplements with a meal to avoid these side effects and reduce the fishy odor by adding the fish oil to a smoothie, yogurt or consume with lemon water.  Our Nordic Naturals brand of cod liver oil tastes like lemon oil and does not have a fishy flavor or after taste and won’t cause bad breath.

If you are belching or have heart burn after using cod liver oil, it is possible you have low stomach acid or a sluggish gall bladder.  Consider these possibilities and reduce your dosage of cod liver oil and see if the complaints continue.  If so, discontinue use until you discover what the root cause is.  Overall, the benefits of cod liver oil earn it the pass to try it out and see how you do with it.

Contraindications For Cod Liver Oil Usage:

Cod liver oil can act as a blood thinner, slowing blood clotting and decreasing blood pressure. Pregnant and nursing women should consult with their doctor before beginning a regimen to be sure they are taking a safe and effective dose.  I am personally a huge fan of pregnant or nursing women using cod liver oil, but to be sure, it is always wise to consult with your physician first.

Individuals taking anticoagulant or blood pressure medication should also understand how cod liver oil can interact with such drugs. These individuals may experience hypotension and increased risk of bruising and bleeding.  As a clinician, I have found that 99.9% of my clients do great on this, but there are always a unique few that need to be on the lookout, as with any supplement.  Now you understand the great benefits of cod liver oil usage!

cod liver oil

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2. Laerum BN, et al. Relationship of fish and cod oil intake with adult asthma. Clin Exp Allergy. 2007 Nov; 37(11): 1616-23. PMID: 17877766
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9. UNH Daily: Natural Osteoporosis Treatment: Cod Liver Oil Benefits Include Strengthening Bones Link Here
10. Lorincz C, Manske SL, Zernicke R. Bone Health: Part 1, Nutrition.Sports Health. 2009; 1(3):253-260. PMCID: 344524310.
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glaucoma, Glaucoma: Symptoms, Causes and Natural Support Strategies

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Dr David Jockers is passionate about seeing people reach their health potential in mind, body and spirit. He is the host of the popular “Dr Jockers Functional Nutrition” podcast and the author of the best-selling books, “The Keto Metabolic Breakthrough” and “The Fasting Transformation.”


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  1. I’m looking for a new brand of cod liver oil I’m a bit confused by part of your article though and cod liver vitamin rations in general!

    You said cod liver oil should provide 5000 IU Vitamin A and 500-1000 IU of Vitamin D in 1 tsp. The label of the Nordic Naturals Arctic D cod liver oil you link to says it provides 230-920 IU Vitamin A and 1000 IU of Vitamin D per tsp.

    Two things:
    – Isn’t the A to D ratio way too low?
    – What is the source of the vitamin D that is added?

    The non-D Nordic Natural Arctic Cod Liver Oil label says it contains 127-885 mcg RAE of Vitamin A (419-2920 IU) and only 0 – 0.5 mcg Vitamin D (about 20 IU). That ratio of A to D seems way to high! (If my RAE and mcg conversions were correct…).

    I thought cod liver naturally contained Vit D. Some brands claim they don’t add vitamin d to their raw oil and have over 300 IU of D per tsp. Why does Nordic Naturals need to add vitamin D?

    Is there an organization that oversees quality assurance to make sure cod liver oils aren’t rancid? That’s one of main concerns….

    1. Nordic over processes their oil. They have 2 versions of Cod Liver Oil. One has almost ZERO D and A because of over processing. The other has D added from lanolin (sheeps wool). Carlson is the only one that has all natural D and A from Cod. Carlson is also processed and bottled in Norway while Nordic is “processed” in Norway but shipped in drums to a manufacturer in the USA for final processing and bottling. They do a great job of marketing to make their procucts seem the “best” you can buy. No I don’t work for Carlson but have been using their oil since 2001. I have tried Nordic but within 2 weeks my joints started aching again. Back to Carlson and back to normal.

  2. I am looking into cod liver oil for my 3 year old. Wondering if it ok to give him this and how much to give per day.

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