Research-Supported Benefits of Cod Liver Oil

Cod liver oil has numerous science-backed health benefits and is different from regular fish oil. Typical fish oil is extracted from the oily, fatty fish tissue of tuna, herring, anchovies, or mackerel. In contrast, cod liver oil is derived from cod livers, which are rich in many nutrients.

A cod’s liver contains vitamins A and D and is high in omega-3 fatty acids, which can help to reduce inflammation and lower blood pressure [1] [2].

In this article, we will review a few of the many research-supported benefits of cod liver oil.

Contains High Levels of Vitamins A and D

Cod liver oil has been given to children for centuries to help treat rickets, a disease of vitamin D deficiency that causes fragile bones [3] [5], and this makes sense because one teaspoon of cod liver oil contains 113% of the recommended daily intake (RDI) [4].

Likewise, one teaspoon provides 90% of the RDI of vitamin A, an essential vitamin for maintaining eye health, brain function, and healthy skin [6] [7]. Plus, taking vitamin A with fat, like oil, can increase its absorption [8].

Can Help Reduce Inflammation

While inflammation is a natural bodily function to help fight infections and heal injuries, chronic and long-term inflammation can increase disease risk. Research has shown that chronic systemic inflammation can promote cardiovascular disease, cancer, diabetes mellitus, chronic kidney disease, and autoimmune and neurodegenerative disorders [9] [10].

The Journal of the American College of Nutrition revealed that “many of the placebo-controlled trials of fish oil in chronic inflammatory diseases reveal significant benefits, including decreased disease activity and a lowered use of anti-inflammatory drugs” [1]. The author noted the oil’s anti-inflammatory effect is likely due to its potent omega-3 properties since omega-3 may suppress inflammatory proteins, like TNF-α, IL-1, and IL-6. Thus, its supplementation might be useful in the management of inflammatory and autoimmune diseases [1].

Also, since vitamins A and D are antioxidants, they help reduce inflammation by neutralizing harmful free radicals [11] [12], which is interesting because research shows that people who are deficient in these vitamins are at a higher risk of chronic inflammation [13] [14] [15].

Bone Health

Most people reach peak bone mass between 25 and 30, and by 40, people begin to slowly lose bone mass [16]. This can lead to conditions like osteopenia, a condition where bone mass decreases, creating weaker, fracture-prone bones, especially in women after menopause [17] [18] [19].

Research has shown that vitamin D helps promote efficient calcium absorption in the intestinal tract, and cod liver oil is an excellent source of vitamin D [5] [20]. In a 2016 study published in Nature, scientists noted that an adequate vitamin D level is a reasonable approach to help maintain skeletal health and prevent fragile bones [21].

Plus, for people who live in cold climates or far from the equator, taking a cod liver oil supplement is helpful since it is difficult to get enough vitamin D through sunlight [22].

Joint Pain and Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an autoimmune and inflammatory disease that causes inflammation in various body parts, particularly the joints [23]. Research suggests that cod liver oil can reduce joint pain and improve stiffness and swelling symptoms [24] [25].

In one study, researchers gave 43 arthritic patients 1g of cod liver oil daily for three months [24]. Researchers noted a decrease in morning stiffness (-52.4%), painful (-42.7%) and swollen (-40%) joints, and pain intensity (-65.7%), and the patients overwhelmingly rated the overall effects either “good” or “very good.” The researchers concluded, “Cod liver oil can be recommended for the treatment of rheumatoid arthritis” [24].

In another study, researchers noted that cod liver oil can decrease an RA patient’s need for NSAIDs since 39% of patients in the oil group reduced their NSAID intake over the 9-month study [25]. And a 2013 study found when diclofenac (an NSAID) was combined with a 3,000mg daily dose of cod liver oil, the patient’s pain parameters and diclofenac intake significantly decreased over the 24-week study period [26].

Eye Health

Vision loss affects over 285 million people worldwide [27], and the two leading causes of vision loss are glaucoma and age-related macular degeneration (AMD). Research has shown that patients with these vision diseases have significantly elevated inflammatory biomarkers [28].

However, cod liver oil has potent levels of omega-3 fatty acids and vitamin A; both have been shown to protect against inflammatory eye diseases [7] [29] [30].

In a 2011 study, researchers noted those whose diet contained the highest omega-3 levels have a 17% lower risk of early AMD and 41% lower risk of late AMD [30].

Likewise, a 2018 meta-analysis noted that dietary intake of vitamins A and C showed a beneficial association with glaucoma [31], which is likely due to both vitamins’ anti-inflammatory and antioxidant properties. Additional studies found that omega-3 fatty acids reduced risk factors associated with glaucoma, such as nerve damage and eye pressure [32] [33] [34].

Heart Disease

Numerous studies show that people who eat fish regularly have a significantly lower risk of heart disease, and this benefit can be ascribed to fish’s omega-3 content [35] [36].

For example, a 2005 study with nearly 5,000 participants found that fish intake (excluding fried fish) reduces the risk of heart failure [37], and one study noted that fish oil supplements may reduce inflammatory biomarkers in patients with chronic heart failure [38].

Indeed, researchers have investigated the relationship between omega-3 supplements and a wide range of cardiovascular diseases.

For example, studies have found that dietary supplementation with omega-3 fatty acids reduces sudden cardiac death in patients with myocardial infarction (heart attack) [39-41]. Plus, consuming omega-3 fatty acids is associated with reduced coronary heart disease and arterial plaquing, decreased blood pressure, and better cholesterol profiles [42-48].

Anxiety and Depression

Studies have shown a corollary relationship between chronic inflammation and depression and anxiety [49] [50], so omega-3 fatty acids in cod liver oil may help decrease inflammation and inflammatory biomarkers that are associated with anxiety and depression symptoms [49] [50].

In a Norwegian study with over 20,000 participants, researchers found that regular use of cod liver oil was negatively associated with high levels of depressive symptoms [51]. Additional studies found a similar effect with omega-3 and vitamin D supplementation [52-54].


Cod liver oil has many research-backed benefits, including its ability to decrease inflammation, promote eye, bone, and cardiovascular health, and alleviate arthritis symptoms. For most people, cod liver oil is accessible to add to their diet. Some people elect to eat cod and fish regularly, but most take a cod liver oil supplement. Healthmasters offers two high-quality cod liver oil supplements: Oil Fashioned Cod Liver Oil and Fermented Cod Liver Oil.

If you are interested in these products and would like more information, please call our office at 800.726.1834.