Cod liver oil
Cod liver oil is a nutritional supplement derived from liver of cod fish. As with most fish oils, it has high levels of the omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Cod liver oil also contains vitamin A and vitamin D. It has historically been taken because of its vitamin A and vitamin D content. It was once commonly given to children, because vitamin D has been shown to prevent rickets and other symptoms of vitamin D deficiency.
Cod liver oil was traditionally manufactured by filling a wooden barrel with fresh cod livers and seawater and allowing the mixture to ferment for up to a year before removing the oil. Modern cod liver oil is made by cooking the whole cod body tissues of fatty fish during the manufacture of fish meal.
Cod liver oil is widely taken to ease the pain and joint stiffness associated with arthritis. It may have a positive effect on heart, bone, as well as helping to repair wounded skin, hair, nails, and teeth.
Cod liver oil and fish oil are similar, but cod liver oil has higher levels of vitamins A and D. According to the USDA, a tablespoon (4 drams or 15 ml) of cod liver oil (13.6 g) contains 4080 μg of retinol (vitamin A) and 34 μg of vitamin D. The Recommended Dietary Allowance of vitamin A is 900 μg per day for adult men and 700 for women, while that for vitamin D is 15 μg per day. The "tolerable upper intake levels" are 3000 μg/day and 100 μg/day respectively, so people consuming cod liver oil as a source of omega-3 fatty acids should pay attention to how much vitamin A and vitamin D this adds to their diet. A 300 mg soft gelatin capsule like those made by brands like seven seas and seacod by sanofi contain approximately 88 μg vitamin A per dose .
Use of cod liver oil during pregnancy is associated with lower risk of Type I diabetes in the offspring. (although see adverse effects below). This effect was found only in mothers taking cod liver oil, not in mothers taking multivitamin supplements. Cod liver oil taken by nursing mothers improves the breast milk by increasing the amount of fatty acids, which promotes brain development, and the amount of vitamin A, which helps prevent infections, but the level of vitamin D is unchanged.
A Norwegian study of more than 68,000 women reported that female cancer patients who took daily cod liver oil supplements had significantly reduced mortality (25% for all cancers, 45% for lung cancer) compared to women who did not take such supplements.
Per tablespoon (13.6 g), cod liver oil contains 136% of the established daily Tolerable Upper Intake Level (UL) for Preformed Vitamin A (Retinol). Vitamin A accumulates in the liver, and can reach harmful levels sufficient to cause hypervitaminosis A. Pregnant women may want to consider consulting a doctor when taking cod liver oil because of the high amount of natural forms of vitamin A such as retinol. High doses of synthetic vitamin A (retinoids) have been shown to cause birth defects. A toxic dose of retinol (vitamin A) is around 25 000 IU/kg (see Retinol#Retinoid overdose (toxicity)), or the equivalent of about 1.25 kg of cod liver oil for a 50 kg person.
The risks of hypervitaminosis and of exposure to environmental toxins such as mercury, polychlorinated biphenyls (PCBs), dioxins, and other contaminants, are reduced when purification processes are applied to produce refined fish-oil products, which consequently contain raised levels of omega-3 fatty acids, such as EPA and DHA.
- Rajakumar, K. Vitamin D, Cod-Liver Oil, Sunlight, and Rickets: A Historical Perspective. 2003. Pediatrics 112(2):132-135.
- David Wetzel (28 February 2006). "Cod Liver Oil Manufacturing". The Weston A. Price Foundation.
- Gruenwald J, Graubaum HJ, Harde A (2002). "Effect of cod liver oil on symptoms of rheumatoid arthritis". Adv Ther 19 (2): 101–7. doi:10.1007/bf02850059. PMID 12069368.
- Knapp, HR, et al. (1987). "The Effect of Cod liver oil on the Development of Atherosclerosis in an Animal Model.". Proceedings of the AOCS: pp. 35–40.
- von Schacky, C. (2000). "n-3 Fatty acids and the prevention of coronary atherosclerosis". Am J Clin Nutr 71 ((1 Suppl)): 224S–7S. PMID 10617975.
- Akpede, GO, et al.; Omotara, B.A.; Ambe, J.P. (1999). "Rickets and deprivation: a Nigerian study.". J R.Soc.Health 119 (4): 216–22. doi:10.1177/146642409911900403.
- Terkelsen, LH, et al. (2000). "Topical application of cod liver oil ointment accelerates wound healing: an experimental study in wounds in the ears of hairless mice.". J Plast. Reconstr. Surg. 34 (1): 15–20. doi:10.1080/02844310050160123.
- Paul Lips (8 May 2003). "Hypervitaminosis A and fractures". N Engl J Med 348 (4): 1927–1928. doi:10.1056/NEJMe020167. PMID 12540650. Retrieved 6 March 2008.
- Haddad J.G. (30 April 1992). "Vitamin D — Solar Rays, the Milky Way, or Both?". The New England Journal of Medicine. Retrieved 29 January 2012.
- Swank, Roy L., and Barbara Brewer Duggan. The Multiple Sclerosis Diet Book: A Low-Fat Diet for The Treatment of MS. Doubleday, 1987.
- Stene LC, Ulriksen J, Magnus P, Joner G (September 2000). "Use of cod liver oil during pregnancy associated with lower risk of Type I diabetes in the offspring". Diabetologia 43 (9): 1093–8. doi:10.1007/s001250051499. PMID 11043854.
- Lund, Eiliv; Vanessa Dumeaux; Tonje Braaten; Anette Hjartåker; Dagrun Engeset; Guri Skeie; Merethe Kumle (6 June 2007). "Cohort Profile: The Norwegian Women and Cancer Study—NOWAC—Kvinner og kreft". International Journal of Epidemiology (Oxford University Press) 2008 (37(1)): 36–41. doi:10.1093/ije/dym137. PMID 17644530. Retrieved 12 October 2007.
- Skeie, G; Braaten T; Hjarta A; Brustad M; Lund E. "Cod liver oil, other dietary supplements and survival among cancer patients with solid tumors.". Int J Cancer 125: 1155–60. doi:10.1002/ijc.24422. PMID 19444919.
- National Nutrient Database for Standard Reference "USDA Nutrition Facts: Fish oil, cod liver" USDA
- Jane Higdon, Ph.D. of the Linus Pauling Institute "Linus Pauling Institute Micronutirent Center" Oregon State University
- Myhre AM, Carlsen MH, Bøhn SK, Wold HL, Laake P, Blomhoff R (December 2003). "Water-miscible, emulsified, and solid forms of retinol supplements are more toxic than oil-based preparations". Am. J. Clin. Nutr. 78 (6): 1152–9. PMID 14668278.
- Theodore M. Brasky, Amy K. Darke, Xiaoling Song, Catherine M. Tangen, Phyllis J. Goodman, Ian M. Thompson, Frank L. Meyskens Jr, Gary E. Goodman, Lori M. Minasian, Howard L. Parnes, Eric A. Klein and Alan R. Kristal (2013). "Plasma Phospholipid Fatty Acids and Prostate Cancer Risk in the SELECT Trial". J Natl Cancer Inst 105 (15): 1132–1141. doi:10.1093/jnci/djt174.
- Bays H E (19 March 2007). "Safety Considerations with Omega-3 Fatty Acid Therapy". The American Journal of Cardiology. 99. (Supplement 1) (6): S35–S43. doi:10.1016/j.amjcard.2006.11.020. PMID 17368277.
- Olafsdottir AS, Skuladottir GV, Thorsdottir I, Hauksson A, Thorgeirsdottir H, Steingrimsdottir L (March 2006). "Relationship between high consumption of marine fatty acids in early pregnancy and hypertensive disorders in pregnancy". BJOG 113 (3): 301–9. doi:10.1111/j.1471-0528.2006.00826.x. PMID 16487202.
- Punt (boat)
|Wikimedia Commons has media related to Cod liver oil.|