Cod liver oil is exactly what is sounds like: oil extracted from the livers of codfish. It does not contain added vitamin A because there is so much vitamin A already in this product. Don't confuse fish oil with cod liver oil because their nutritional profiles are very different.
Cod Liver Oil
The Berkeley Wellness Guide to Dietary Supplements states that giving cod liver oil to children used to be a popular practice. These days, cod liver oil appeals largely to older people who take it to treat arthritis. The Foundation for IgA Nephropathy points out that since regular fish oil is higher in omega-3 fatty acids, it may be more beneficial and less risky than cod liver oil because it does not have dangerously high levels of vitamin A
Vitamin A
The USDA reports that 1 tbsp. of cod liver oil has 13,600 IU of vitamin A. The recommended daily allowance for vitamin A is 3,000 IU for adult men and 2,333 IU for adult women. The Foundation for IgA Nephropathy warns that people who take cod liver oil as if it were fish oil are at high risk of vitamin A toxicity. For example, patients with IgA nephropathy often take 12 g of fish oil per day. If cod liver oil were taken at such doses, vitamin A toxicity would result.
Symptoms of Toxicity
The Berkeley Wellness Guide to Dietary Supplements cautions that high levels of vitamin A cause weak bones and birth defects. They point to studies such as the one appearing in the June 2005 issue of the "Journal of Bone and Mineral Research," which examined the relationship between biochemical retinol status and fractures in older women and concluded that vitamin A supplementation could be harmful even within recommended limits.
Warning
Discuss matters pertaining to dietary supplementation with your doctor before starting any supplement regimen. He can evaluate the benefits and risks of the supplement with respect to your overall health status. Cod liver oil is not for everyone, especially kidney patients on dialysis who are at risk for vitamin A toxicity.
References
- Foundation for IgA Nephropathy: Fish Oil
- Mayo Clinic: Vitamin D; July 2011
- Berkeley Wellness Guide to Dietary Supplements; Cod Liver Oil;
- "Journal of Bone Minereral Research"; Serum Retinoids and Beta-Carotene as Predictors of Hip and Other Fractures in Elderly Women; .M.E. Barker, et al.; January 2005
- Davita: ABC's of Vitamins for Kidney Patients
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