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Benefits of Cod Liver Oil

Reviewed by·PharmD, BCPS

This content is for informational purposes only and does not constitute medical advice. Consult your healthcare provider before starting any supplement. Full disclaimer

Evidence-Based Benefits

  • Bone health — cod liver oil's vitamin D3 content promotes calcium absorption and bone mineralization, while omega-3s reduce bone resorption. The VITAL study (Manson et al., 2019) and decades of research confirm vitamin D supplementation reduces fracture risk in deficient populations
  • Cardiovascular protection — EPA and DHA from cod liver oil reduce triglycerides, lower blood pressure, and decrease inflammatory markers. A meta-analysis by Aung et al. (2018) of 77,000+ participants found omega-3 supplementation reduced coronary heart disease events
  • Immune function — vitamins A and D are both critical for immune regulation. Vitamin D activates antimicrobial peptides (cathelicidin) while vitamin A maintains mucosal barrier integrity. Martineau et al. (2017) meta-analysis showed vitamin D supplementation reduced respiratory tract infections
  • Anti-inflammatory effects — EPA and DHA are precursors to specialized pro-resolving mediators (resolvins, protectins) that actively resolve inflammation. Goldberg & Katz (2007) meta-analysis found fish oil supplementation significantly reduced joint pain and morning stiffness in rheumatoid arthritis
  • Eye health — DHA is a major structural component of retinal photoreceptors, and vitamin A (retinol) is essential for rhodopsin synthesis. Combined, they support both structural and functional aspects of vision

What the Research Says

Cod liver oil has one of the longest research histories of any supplement, dating to controlled studies on rickets in the 18th century. The evidence base draws from both cod liver oil-specific studies and the broader omega-3 and vitamin D literature. For bone health, vitamin D's role in calcium absorption and fracture prevention is well-established, with the VITAL study (Manson et al., 2019) being the largest randomized trial. For cardiovascular outcomes, Aung et al. (2018) published a major meta-analysis of 10 trials (77,917 participants) showing omega-3 supplementation reduced coronary heart disease events by 8%. Martineau et al. (2017) meta-analyzed 25 RCTs and found vitamin D supplementation reduced acute respiratory tract infections, particularly in deficient individuals. For joint inflammation, Goldberg & Katz (2007) confirmed fish oil reduces pain and stiffness in rheumatoid arthritis. The Rajakumar (2003) historical review documented cod liver oil's critical role in eliminating rickets as a public health problem. The key distinction from regular fish oil — the vitamin A content — is both an advantage (synergistic immune and bone benefits) and a limitation (toxicity ceiling). Evidence is classified as Moderate because while omega-3 and vitamin D evidence is individually strong, cod liver oil-specific RCTs are fewer than those for purified fish oil or vitamin D alone.

Related Conditions

Bone HealthImmune FunctionHeart HealthInflammationEye Health
Full Cod Liver Oil Guide

References

  1. Manson JE, Cook NR, Lee IM, Christen W, Bassuk SS, Mora S, Gibson H, Gordon D, Copeland T, D'Agostino D, Friedenberg G, Ridge C, Bubes V, Giovannucci EL, Willett WC, Buring JE (2019). Vitamin D supplements and prevention of cancer and cardiovascular disease. New England Journal of Medicine. DOI PubMed
  2. Aung T, Halsey J, Kromhout D, Gerstein HC, Marchioli R, Tavazzi L, Geleijnse JM, Rauch B, Ness A, Galan P, Chew EY, Bosch J, Collins R, Lewington S, Armitage J, Clarke R (2018). Associations of omega-3 fatty acid supplement use with cardiovascular disease risks: meta-analysis of 10 trials involving 77917 individuals. JAMA Cardiology. DOI PubMed
  3. Martineau AR, Jolliffe DA, Hooper RL, Greenberg L, Aloia JF, Bergman P, Dubnov-Raz G, Esposito S, Ganmaa D, Ginde AA, Goodall EC, Grant CC, Griffiths CJ, Janssens W, Laaksi I, Manaseki-Holland S, Mauger D, Murdoch DR, Neale R, Rees JR, Simpson S, Stelmach I, Kumar GT, Urashima M, Camargo CA (2017). Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data. BMJ. DOI PubMed
  4. Goldberg RJ, Katz J (2007). A meta-analysis of the analgesic effects of omega-3 polyunsaturated fatty acid supplementation for inflammatory joint pain. Pain. DOI PubMed
  5. Rajakumar K (2003). Vitamin D, cod-liver oil, sunlight, and rickets: a historical perspective. Pediatrics. DOI PubMed
  6. Gruenwald J, Graubaum HJ, Harde A (2002). Effect of cod liver oil on symptoms of rheumatoid arthritis. Advances in Therapy. DOI PubMed