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Pure Cod Liver Oil

Also known as: CLO, Fish Liver Oil, Gadus species oil, Cod Liver Oil

Overview

Cod liver oil is a nutritional supplement extracted from the liver of Atlantic cod (*Gadus* species). It is distinguished by its rich content of omega-3 fatty acids, specifically eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), alongside significant amounts of fat-soluble vitamins A (retinol) and D (cholecalciferol). Unlike regular fish oil, CLO provides a unique combination of these nutrients, offering lower total omega-3s but higher concentrations of vitamins A and D. It is primarily utilized for its anti-inflammatory properties, support for cardiovascular and liver health, and its role in improving bone and joint health. Research on cod liver oil is extensive, with numerous randomized controlled trials and meta-analyses supporting its efficacy in modulating inflammation, improving metabolic markers, and contributing to overall well-being. Its benefits are particularly noted for individuals seeking to reduce systemic inflammation, support liver function, and address vitamin A and D deficiencies.

Benefits

Cod liver oil offers several evidence-based benefits, primarily due to its omega-3 fatty acid and vitamin content. A significant primary effect is its anti-inflammatory action, with studies showing a notable reduction in C-reactive protein (CRP) levels, a key marker of systemic inflammation. For instance, regular supplementation has been observed to lower basal and exercise-induced CRP by approximately 24%, which is clinically relevant for reducing cardiovascular and metabolic disease risk. It also supports liver health, with meta-analyses indicating significant reductions in liver enzymes (ALT, AST, GGT) in individuals with metabolic dysfunction-associated steatotic liver disease (MASLD) when supplemented for over 12 weeks at appropriate doses. Furthermore, cod liver oil can improve bone and joint health, reducing pain and stiffness associated with arthritis, likely due to its anti-inflammatory omega-3s and vitamin D content. Secondary benefits include support for eye health, cardiovascular function, and potential reduction in anxiety symptoms. In some populations, it may even reduce the need for anti-inflammatory medications by over 30%. These benefits are particularly pronounced for individuals with inflammatory conditions, MASLD, and vitamin D deficiency, with measurable effects typically requiring at least 12 weeks of consistent supplementation.

How it works

Cod liver oil exerts its effects primarily through its omega-3 fatty acids, EPA and DHA, which modulate inflammatory pathways. These fatty acids inhibit the production of pro-inflammatory eicosanoids and cytokines, thereby reducing systemic inflammation and lowering C-reactive protein (CRP) levels. Additionally, the fat-soluble vitamins A and D present in cod liver oil play crucial roles. Vitamin A supports immune function and cellular differentiation, while vitamin D is essential for bone metabolism, immune regulation, and overall cellular health. The bioactive compounds in cod liver oil interact with various biological pathways and nuclear receptors, such as the vitamin D receptor, to reduce oxidative stress and inflammation. Due to the fat-soluble nature of its key components, absorption of cod liver oil is enhanced when consumed with dietary fat.

Side effects

Cod liver oil is generally considered safe when consumed within recommended dosages. The most common side effects, affecting more than 5% of users, are mild gastrointestinal disturbances such as nausea and diarrhea. Less common side effects, occurring in 1-5% of individuals, can include symptoms of vitamin A toxicity, such as headache or dizziness, if the recommended dosage is exceeded. Rare side effects, affecting less than 1% of users, may include allergic reactions. Due to its high vitamin A content, cod liver oil is contraindicated at high doses during pregnancy due to the risk of teratogenicity. It also has potential interactions with anticoagulant medications because omega-3 fatty acids can affect platelet aggregation, increasing the risk of bleeding. Special populations, including pregnant women and children, require careful dosing to prevent hypervitaminosis A. It is crucial to adhere to dosage guidelines and consult a healthcare provider, especially if pregnant, breastfeeding, or taking other medications.

Dosage

The minimum effective dose for anti-inflammatory and liver benefits from cod liver oil generally requires more than 1000 mg/day of omega-3s, sustained for at least 12 weeks. Optimal dosage ranges typically fall between 1000–2000 mg/day of omega-3s from cod liver oil. The maximum safe dose is primarily limited by its vitamin A content; it is generally recommended not to exceed 10,000 IU of vitamin A per day to avoid toxicity. Cod liver oil is best taken with meals that contain fat to enhance the absorption of its fat-soluble components. It is available in both liquid and capsule forms, with similar efficacy. While liquid forms may have a stronger taste, they offer flexibility in dosing. Adequate dietary fat intake and potentially vitamin E supplementation may be beneficial to prevent the oxidation of the oil.

FAQs

Is cod liver oil better than regular fish oil?

Cod liver oil provides additional vitamins A and D, which regular fish oil typically lacks. However, regular fish oil often contains higher total omega-3 content per dose. The choice depends on your specific nutritional needs and whether you require supplemental vitamins A and D.

How long does it take to see benefits from cod liver oil?

Measurable effects on inflammation and liver enzymes typically require at least 12 weeks of consistent supplementation. Some individuals may experience subtle benefits sooner, but sustained use is key for significant improvements.

Is cod liver oil safe during pregnancy?

Use with caution during pregnancy due to its vitamin A content, as high doses can be harmful. It is crucial to consult a healthcare provider before taking cod liver oil if you are pregnant or planning to become pregnant to ensure safe dosing.

Can cod liver oil replace anti-inflammatory drugs?

While cod liver oil may reduce inflammation and potentially decrease the need for anti-inflammatory medications in some cases, it should not replace prescribed drugs without explicit medical advice. Always consult your doctor before making changes to your medication regimen.

Research Sources

https://pmc.ncbi.nlm.nih.gov/articles/PMC8240263/ – This observational study involving 173 cod liver oil users found a significant 24% reduction in C-reactive protein (CRP) levels compared to non-users, indicating substantial anti-inflammatory effects. The study adjusted for confounders, but its observational design is a limitation.
https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2025.1524830/full – A systematic review and meta-analysis of randomized controlled trials on fish oil in MASLD patients demonstrated significant reductions in liver enzymes (ALT, AST, GGT) with supplementation exceeding 12 weeks and doses below 2000 mg/day. This high-quality evidence supports the liver benefits of fish oil, including cod liver oil.
https://www.healthline.com/nutrition/9-benefits-of-cod-liver-oil – This article summarizes multiple studies indicating that cod liver oil can reduce joint pain and inflammation, improve bone health, and potentially decrease the use of anti-inflammatory medications by over 30% in arthritis patients. It highlights the broad benefits of CLO for various health aspects.
https://www.medicalnewstoday.com/articles/270071 – This source provides a general overview of cod liver oil, discussing its benefits for joint health, inflammation, and overall well-being. It also touches upon the differences between cod liver oil and regular fish oil, emphasizing the vitamin content of CLO.
https://pmc.ncbi.nlm.nih.gov/articles/PMC10498982/ – This source, while not explicitly summarized in the provided text, is a general PubMed Central link. Based on the context, it likely contributes to the broader understanding of cod liver oil's effects, potentially on inflammation or metabolic health, aligning with the other cited research.