Omega-3 fatty acids are important nutrients that support normal bodily processes involving your brain, nerves and heart. Your body cannot produce these nutrients on its own. You must get them from food sources or supplements. Fish oil and cod liver oil both provide omega-3 fatty acids, but each varies in dosage and significant nutritional differences exist between supplements. In choosing which works best, consider your health needs in consultation with your physician.
Fish Oil Sources
Fish oil comes from the entire body of cold-water fatty fish including salmon, tuna, herring, trout and mackerel. A 3.5-oz. serving of these types of fish may give you up to 1 g of essential omega-3 fatty acids. Supplemental forms of fish oil come in capsules or extract, and dosing varies depending on manufacturer labeling. A prescription-strength fish oil medication is also available as an FDA approved triglyceride-lowering agent. Triglycerides are fats that accumulate in your bloodstream that may cause heart complications.
Cod Liver Oil Sources
Unlike fish oil, cod liver oil comes only from the liver of the codfish. You can consume the actual liver from a codfish but it may contain high levels of toxins because it acts as a toxin processor. Producers generally purify supplemental cod liver oil during processing, but polychlorinated biphenyls, toxic pollutants, may still be present, notes UC Berkeley Wellness. Cod liver oil supplements are not FDA regulated and dosing varies per manufacturer.
Additional Nutrients in Cod Liver Oil
Cod liver oil contains high concentrations of vitamin A, approximately 1,350 mcg, in a 1-tsp. serving, which is well above the recommended tolerable upper intake level. Vitamin A serves important functions in visual and immune system health, but excessive dosing increases your risk of toxicity and liver damage, notes the Linus Pauling Institute. The daily-recommended intake for vitamin A is 700 to 900 mcg and the upper limit is 3,000 mcg. According to an editorial written by Dr. Robert C. Oh, published in the "Journal of the American Board of Family Medicine," typical dosing for cod liver oil often exceeds safe vitamin A intake limits and consumers as well as physicians should heed caution in using this supplement.
Concerns and Considerations
Fish oil supplements are safe in moderate doses of 3 g or less per day. However, side effects include heartburn, bloating, belching, gas and loose stool. Fish oil can increase your risk of bleeding and may not be beneficial if you have existing liver disease or if you take medications for high blood pressure. Consult your physician to decide the best supplement to take based on your health condition. Consumption of fresh fish instead of supplements is a primarily recommendation because the benefits of eating fish may outweigh the consequences of prolonged supplement use, notes the American Cancer Society.
References
- Journal of the American Board of Family Medicine; Fish Oil Versus Cod Liver Oil; Is Vitamin D a Reason to Go Back to the Future?; Letter to the Editor; Robert C. Oh, M.D.; 2005
- UC Berkeley Wellness: Cod Liver Oil
- American Cancer Society: Omega-3 Fatty Acids
- Linus Pauling Institute: Vitamin A
- Office of Dietary Supplements: Vitamin D
- MedlinePlus: Fish Oil
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