People take cod liver oil for the health benefits of obtaining vitamin D, vitamin A and omega-3 fatty acids. The idea that something is good for health may lead to over-consumption of a certain food or supplement. More is not always better and being mindful of potential side effects associated with supplements, such as cod liver oil is prudent. Speak with a physician regarding taking cod liver oil to prevent adverse events.
Vitamin A toxicity
Cod liver oil is rich in vitamin A. The amount of vitamin A in 1 tsp. of cod liver oil is 4,500 IU. The RDA upper limit for vitamin A is 10,000 IU. Therefore, an overdose or toxicity of vitamin A from cod liver oil is not difficult to do. This is especially detrimental to pregnant women since toxic levels of vitamin A can lead to birth defects, explains a study in the 2003 "American Journal of Clinical Nutrition" led by reseacher Anne Myhre. Another downside for too much vitamin A is that it can lead to hypertension during pregnancy as explained in a 2007 study in the "International Journal of Obstetrics and Gynaecology" led by researcher A.S. Olafsdottir.
Contaminants
Too much cod liver oil may contribute to contaminants in the body. Cod liver oil is made from fish livers that filter out toxins. Therefore, certain contaminants will be deposited in the body, like PCB's or polychlorinated biphenyls which are known pollutants, explains the Berkeley Wellness Letter. Stick to the recommended amount of cod liver oil to prevent contaminant buildup. More importantly, use a high quality cod liver oil to ensure it has undergone a purifying process.
Bleeding
Too much cod liver oil can provide an excess of omega-3 fatty acids, which can lead to excessive bleeding, explains the Mayo Clinic. This effect is discussed in a study in the 2002 journal "Annals of Pharmacotherapy" led by researcher D. Carroll. The study explains there is a risk of bleeding with the use of fish oils, though larger amounts increase the risk. Omega-3 fats act to thin the blood, which allows blood to flow easier and decreases clotting ability.
References
- "American Journal of Clinical Nutrition"; Water-miscible, Emulsified, and Solid Forms of Retinol Supplements are More Toxic Than Oil-based Preparations; Myhre, et al.; 2003.
- Berkeley Wellness Letter: Cod Liver Oil
- Mayo Clinic: Podcast: Omega-3 Fatty Acids --- Get the Heart-Health Benefits
- "The Annals of Pharmacotherapy"; Evidence for the Cardioprotective Effects of Omega-3 Fatty Acids; Carroll, et al.; 2002.
- "The International Journal of Obstetrics and Gynaecology"; Relationship Between High Consumption of Marine Fatty Acids in Early Pregnancy and Hypertensive Disorders in Pregnancy; Olafsdottir, et al.; 2006.
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