Cod liver oil
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2008-07-14T20:07:24Z
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[[Image:Codliveroilcapsules.jpg|thumb|right|Cod liver oil in [[gelatin]] capsules]]
:''This article is about the fish extract, for the traditional Newfoundland song, see "[[Cod Liver Oil (song)]]".''
'''Cod liver oil''' is a [[dietary supplement|nutritional supplement]] derived from [[liver]] of [[cod|cod fish]]. It has high levels of the [[omega-3]] fatty acids, [[Eicosapentaenoic acid|EPA]] and [[Docosahexaenoic acid|DHA]], and very high levels of [[vitamin A]], and [[vitamin D]]. It is widely taken to ease the symptoms of [[arthritis]] as well as other health benefits. It was once commonly given to [[children]].
==Characteristics==
Depending on the quality of the oil, the [[flavor]] and [[aroma]] range from a mild [[sardine]]-like flavor, to an intense and obnoxious odor of rotten fish and [[rancidification|rancid]] oil. High quality cod liver oil is a pale-yellow, thin, oily liquid, having a peculiar, slightly fishy, but not rancid odor, and a bland, slightly fishy taste. Manufacturers sometimes add flavorings, such as citrus or mint essence, to cod liver oil to make it more palatable.
==Manufacture==
Cod liver oil is made by cooking cod livers with steam, and then pressing/decanting the cooked livers to extract the oil. This is in contrast to [[fish oil]]s, which are extracted from the cooked whole body [[biological tissue|tissues]] of fatty [[fish]] during the manufacture of [[fish meal]].
==Therapeutic uses==
Cod liver oil is widely taken to ease the pain and joint stiffness associated with [[arthritis]],<ref name=PMID12069368>Gruenwald J, Graubaum HJ, Harde A. Effect of cod liver oil on symptoms of rheumatoid arthritis. 2002. Adv Ther 19:101-107. '''PMID 12069368'''</ref> but has also been clinically proven to have a positive effect on heart,<ref name="AOCS">{{cite journal| journal = Proceedings of the AOCS| volume = | issue = | year = 1987| pages = pp. 35-40| title = The Effect of Cod liver oil on the Development of Atherosclerosis in an Animal Model.| last = Knapp| first = HR, et al| url = | format = | accessdate = }}</ref><ref name="Schacky">{{cite journal| journal = Am J Clin Nutr| volume = 71| issue = (1 Suppl)| year = 2000| pages = 224S-7S| title = n-3 Fatty acids and the prevention of coronary atherosclerosis| last = von Schacky| first = C.| url = | format = | accessdate = }}</ref> bone,<ref name="R.Soc.Health">{{cite journal| journal = J R.Soc.Health| volume = 119| issue = | year = 1999| pages = 216-22| title = Rickets and deprivation: a Nigerian study.| last = Akpede | first = GO, et al| url = | format = | accessdate = }}</ref> and brain,<ref>{{cite web|url=http://www.healingdaily.com/detoxification-diet/cod-liver-oil.htm|title=Cod liver oil, fish oil and Omega 3, "Cod liver oil and depression"}}</ref> as well as helping to nourish skin,<ref name="Plast.Reconstr.Surg">{{cite journal| journal = J Plast. Reconstr. Surg.| volume = 34| issue = | year = 2000| pages = 15-20| title = Topical application of cod liver oil ointment accelerates wound healing: an experimental study in wounds in the ears of hairless mice.| last = Terkelsen| first = LH, et al| url = | format = | accessdate = }}</ref> hair, and nails.
Cod liver oil and fish oil are similar, but cod liver oil has much higher levels of vitamins A and D. Many adults don't meet the RDA for Vitamin D.<ref name=Reginster_2005>Reginster JY. The high prevalence of inadequate serum vitamin D levels and implications for bone health. 2005. Curr Med Res Opin 21:579-586. [[Digital object identifier|DOI]]: [http://dx.doi.org/10.1185/030079905X41435 10.1185/030079905X41435] '''PMID 15899107'''</ref><ref name=Calvo_2004>Calvo MS, Whiting SJ, Barton CN. Vitamin D fortification in the United States and Canada: current status and data needs. 2004. Am J Clin Nutr 80:1710S-1716S. '''PMID 15585792''' [http://www.ajcn.org/cgi/content/full/80/6/1710S full text (free)]</ref><ref name=Peterlik_2005>Peterlik M, Cross HS. Vitamin D and calcium deficits predispose for multiple chronic diseases. 2005. Eur J Clin Invest 35:290-304. [[Digital object identifier|DOI]]: [http://dx.doi.org/10.1111/j.1365-2362.2005.01487.x 10.1111/j.1365-2362.2005.01487.x] '''PMID 15860041'''</ref><ref name=PMID15564440>Cantorna MT, Mahon BD. Mounting evidence for vitamin D as an environmental factor affecting autoimmune disease prevalence. 2004. Exp Biol Med (Maywood) 229:1136-1142. '''PMID 15564440''' [http://www.ebmonline.org/cgi/content/full/229/11/1136 full text (free)]</ref>
Cod liver oil is effective in treatment of household burns, due to its high vitamin content, often leaving no burn-related blister.{{Fact|date=July 2008}}
In 2005, a study by researchers at the [[University of California]] found that Vitamin D may lower the risk of developing different types of cancers, halving the chances of getting breast, ovarian, and colon cancers.<ref name=Garland_2006>Garland CF, Garland FC, Gorham ED, et al. The role of vitamin D in cancer prevention. 2006. Am J Public Health 96:252-261. [[Digital object identifier|DOI]]: [http://dx.doi.org/10.2105/AJPH.2004.045260 10.2105/AJPH.2004.045260] '''PMID 16380576'''</ref>
Use of cod liver oil during pregnancy is associated with lower risk of [[Type I diabetes]] in the offspring.<ref name=Stene_2000>Stene LC, Ulriksen J, Magnus P, et al. Use of cod liver oil during pregnancy associated with lower risk of Type I diabetes in the offspring. 2000. Diabetologia 43:1093-1098. [[Digital object identifier|DOI]]: [http://dx.doi.org/10.1007/s001250051499 10.1007/s001250051499] '''PMID 11043854''' [http://www.springerlink.com/content/fu2nr54wncq6n13h/? full-text (free)]</ref> This effect was found only in mothers taking cod liver oil, not in mothers taking multivitamin supplements. It should be noted that cod liver oil contains unsafe amounts of vitamin A for pregnant women. 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.
==Adverse effects==
Because cod liver oil has a very high level of Vitamin A, it is possible to exceed the [[Recommended Dietary Allowance]] (RDA) of vitamin A. Vitamin A accumulates in body fat, and can reach harmful levels sufficient to cause [[hypervitaminosis A]].<ref name="lips2003">{{cite journal | title=Hypervitaminosis A and fractures | author=Paul Lips | journal=N Engl J Med | volume=348 | pages=1927-1928 | date=2003-05-08 | url=http://content.nejm.org/cgi/content/short/348/4/347 | accessdate=2008-03-06}}</ref>Pregnant women should not take cod liver oil due to the high amount of Vitamin A, which, in high doses is shown to cause birth defects.
The risks of hypervitaminosis and of exposure to environmental toxins such as [[mercury (element)|mercury]], [[polychlorinated biphenyl]]s, [[dioxin]]s, 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 [[Eicosapentaenoic acid|EPA]] and [[Docosahexaenoic acid|DHA]].<ref name="bays2007">{{cite journal | author=Bays H E | title=Safety Considerations with Omega-3 Fatty Acid Therapy | journal=The American Journal of Cardiology | volume=99 (Supplement 1) | issue=6 | date=2007-03-19 | pages=S35-S43 | doi=10.1016/j.amjcard.2006.11.020}}</ref>
A high intake of cod liver oil by pregnant women is associated with a nearly five-fold increased risk of gestational hypertension,<ref name=PMID16487202>Olafsdottir AS, Skuladottir GV, Thorsdottir I, et al. Relationship between high consumption of marine fatty acids in early pregnancy and hypertensive disorders in pregnancy. 2006. BJOG 113:301-309. [[Digital object identifier|DOI]]: [http://dx.doi.org/10.1111/j.1471-0528.2006.00826.x 10.1111/j.1471-0528.2006.00826.x] '''PMID 16487202'''</ref> although this study did not control for mercury, which can be present in harmful amounts in fish<ref name="bays2007"/> and which is another cause of hypertension.<ref name=siblings>Horowitz Y, Greenberg D, Ling G, Lifshitz M. Acrodynia: a case report of two siblings. ''Arch Dis Child'' 2002; '''86''': 453. PMID 12023189</ref>
Some urge caution when taking cod liver oil and other fish-based supplements since they may contain elevated levels of toxins such as [[Mercury poisoning|mercury]] and [[Polychlorinated biphenyl|PCBs]] found in fish.<ref name="bays2007"/> Some supplement companies regularly test cod liver oil for purity, while others do not. Ultimately the specific concerns of mercury in cod liver oil are generally not justified. Consumerlab.com tested 44 fish and cod liver oil supplements and found that all were free of detectable levels of mercury. <ref>[http://www.consumerlab.com/results/omega3.asp ConsumerLab.com - Omega-3 Fatty Acids (EPA and DHA) from Fish/Marine Oils review<!-- Bot generated title -->]</ref>
==Other uses==
In [[Newfoundland and Labrador|Newfoundland]], cod liver oil was sometimes used as the liquid base for traditional [[red ochre]] paint, the coating of choice for use on outbuildings and work buildings associated with the cod fishery.
==See also==
* [[Retinol#Retinoid overdose (toxicity)|Vitamin A overdose]]
* [[Shark liver oil]]
== References ==
{{Reflist|2}}
{{Dietary supplement}}
[[Category:Dietary supplements]]
[[Category:Animal fats]]
[[Category:Fish products]]
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