View source for Cod liver oil

{{Short description|Dietary supplement derived from liver of cod fish}}
{{About|the fish oil|the traditional Newfoundland song|Cod Liver Oil (song)}}
{{Redirect|FCLO|the English football team|Leyton Orient FC}}
{{Use dmy dates|date=May 2022}}
[[File:Cod Liver Oil Capsules.jpg|thumb|Modern cod liver oil capsules]]
[[File:Wellcome Foundation Object Wellcome L0044968.jpg|thumb|Cod liver oil with malt extract]]

'''Cod liver oil''' is a [[dietary supplement]] derived from [[liver (food)|liver]] of [[Atlantic cod]] (''Gadus morhua'').<ref>{{Cite web|url=https://www.iffo.com/system/files/downloads/Codex%20Standard%20for%20Fish%20Oils%20CXS_329e_Nov%202017.pdf |title=STANDARD FOR FISH OILS CODEX STAN 329-2017 |date=2017 |access-date = 28 January 2022|website=CODEX ALIMENTARIUS COMMISSION, World Health Organization}}</ref> As with most [[fish oil]]s, it contains the [[omega-3]] fatty acids [[eicosapentaenoic acid]] (EPA) and [[docosahexaenoic acid]] (DHA), and also [[vitamin A]] and [[vitamin D]]. 

Historically, it was given to children in the United States in the 19th century as a patent medicine and by the end of the century was being praised by doctors in medical journals.<ref>{{cite book |last1=Twain |first1=Mark |last2=Smith |first2=Harriet Elinor |last3=Griffin |first3=Benjamin |last4=Fischer |first4=Victor |last5=Frank |first5=Michael B. |last6=Goetz |first6=Sharon K. |last7=Myrick |first7=Leslie Diane |title=Autobiography of Mark Twain |date=2010 |publisher=University of California Press |location=Berkeley, Calif |isbn=9780520267190 |ref=Twain |quote=Cod-liver oil was a common remedy for all diseases, and it was an unspeakably detestable thing to take.}}</ref><ref>{{Cite journal |last=Stone |first=A. |date=1884 |title=On the Practical Uses of Cod-Liver Oil |url=https://doi.org/10.1056/nejm185105140441502 |journal=The Boston Medical and Surgical Journal |volume=44 |issue=15 |pages=292–295 |doi=10.1056/nejm185105140441502 |issn=0096-6762}}</ref> After it was [[Rickets#History|shown]], in 1920, that [[hypovitaminosis D|vitamin D deficiency]] was the cause of [[rickets]], cod liver oil was given as a rich source of vitamin D.<ref>{{cite journal | last1 = Rajakumar | first1 = K. | title = Vitamin D, Cod-Liver Oil, Sunlight, and Rickets: A Historical Perspective. 2003 | journal = Pediatrics | volume = 112 | issue = 2| pages = 132–135 }}</ref><ref>{{cite journal | vauthors = Pileggi VJ, De Luca HF, Steenbock H | title = The role of vitamin D and intestinal phytase in the prevention of rickets in rats on cereal diets | journal = Archives of Biochemistry and Biophysics | volume = 58 | issue = 1 | pages = 194–204 | date = September 1955 | pmid = 13259690 | doi = 10.1016/0003-9861(55)90106-5 }}</ref><ref>{{cite journal | vauthors = Ford JA, Colhoun EM, McIntosh WB, Dunnigan MG | title = Biochemical response of late rickets and osteomalacia to a chupatty-free diet | journal = British Medical Journal | volume = 3 | issue = 5824 | pages = 446–447 | date = August 1972 | pmid = 5069221 | pmc = 1786011 | doi = 10.1136/bmj.3.5824.446 }}</ref>

==Manufacture==
[[File:FMIB 33337 Asellus Major; The Cod-Fish.jpeg|thumb|A cod]]
[[File:Making and loading of cod liver oil.jpg|thumb|Making and loading of cod liver oil, Conche, [[Newfoundland]], 1857]]
Cod liver oil has traditionally come in many grades. Cod liver oil for human consumption is pale and straw-colored, with a mild flavor. Scandinavian [[Vikings]] produced cod liver oil by laying birch tree branches over a kettle of water, and fresh livers were laid over the branches. The water was brought to a boil and as the steam rose, the oil from the liver dripped into the water and was skimmed off. There was also a method for producing fresh raw cod liver oil.<ref name="evclo">{{cite web|title=Extra-Virgin Cod Liver Oil History|url=http://evclo.com/history/|access-date=14 October 2016|url-status=live|archive-url=https://web.archive.org/web/20161011034625/http://evclo.com/history/|archive-date=11 October 2016}}</ref>
 
In the [[Industrial Revolution]], cod liver oil became popular for industrial purposes. Livers placed in barrels to rot, with the oil skimmed off over the season, was the main method for producing this oil. The resulting oil was brown and foul-tasting. In the 1800s cod liver oil became popular as a medicine and both pale and brown oils were used. Brown oils were common because they were cheaper to produce. Some doctors believed in only using the fresh pale oil, while others believed the brown oil was better. The [[Rancidification|rancid]] brown oils tended to cause intestinal upset.<ref name="evclo" />

The Möller Process was invented by Peter Möller in 1850. The livers are ground with water into a slurry, then this is gently simmered until the oil rises to the top. The oil is skimmed off and purified.<ref>{{cite web|title=World Class Processing|url=http://www.mollersomega3.com/c-82-World-class-processing.aspx|access-date=14 October 2016|url-status=dead|archive-url=https://web.archive.org/web/20161016071744/http://www.mollersomega3.com/c-82-World-class-processing.aspx|archive-date=16 October 2016}}</ref> Other methods used in modern times include the Cold Flotation Process, pressure extraction, and pressure cooking. These all require further purification steps to get a pure oil.<ref>{{cite web|title=The Fish Liver Oil Industry|url=http://spo.nmfs.noaa.gov/Fishery%20Leaflets/leaflet233.pdf|access-date=14 October 2016|url-status=live|archive-url=https://web.archive.org/web/20161018212922/http://spo.nmfs.noaa.gov/Fishery%20Leaflets/leaflet233.pdf|archive-date=18 October 2016}}</ref>

==Therapeutic uses==
[[File:A Modern Village School- Education in Cambridgeshire, England, UK, 1944 D23618.jpg|thumb|left|Children being given cod liver oil, Cambridgeshire, England, 1944]]
Though similar in fatty acid composition to other [[fish oil]]s, cod liver oil has higher concentrations of vitamins A and D. According to the [[United States Department of Agriculture]], a [[tablespoon]] (13.6 grams or 14.8 mL) of cod liver oil contains 4,080 [[microgram|μg]] of [[vitamin A]] and 34 μg (1360 IU) of [[vitamin D]].<ref name="USDA">{{cite web |url=https://fdc.nal.usda.gov/food-details/173577/nutrients |title=Fish oil, cod liver |website=U.S. Department of Agriculture |access-date=11 April 2025}}</ref> The [[Dietary Reference Intake]] of vitamin A is 900 μg per day for adult men and 700 μg per day for women. The [[tolerable upper intake level]] (UL) is 3000 μg/day. For children ages 1-3 years the vitamin A RDA and UL are 300 and 600 μg/day, respectively, for children ages 4-8 years 400 and 900 μg/day. 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.<ref name="lips2003">{{cite journal | title=Hypervitaminosis A and fractures | author=Paul Lips | journal=N Engl J Med | volume=348 | pages=1927–28 | date=May 2003 | doi=10.1056/NEJMe020167 | pmid=12540650 | issue=4 }}</ref><ref>{{Cite web |title=Vitamin D – Solar Rays, the Milky Way, or Both? |author=Haddad, JG |url=http://www.nejm.org/search?q=vitamin+d&asug=Vitamin#qs=%3Fq%3D%2522too%2Bmuch%2Bvitamin%2Bd%2522%26date%3Dpast20Years |publisher=The New England Journal of Medicine |date=30 April 1992 |access-date=29 January 2012}}</ref>

Cod liver oil is approximately 20% [[omega-3 fatty acid]]s.<!-- <ref>{{cite web |title=Fish oil, cod liver |url=https://nutritiondata.self.com/facts/fats-and-oils/628/2 |website=Nutrition Data |access-date=19 March 2019}}</ref> --> For this reason, cod liver oil may be beneficial in [[Preventive healthcare#Secondary prevention|secondary prophylaxis]] after a [[myocardial infarction|heart attack]].<ref name=Schacky2000>{{cite journal |last=von Schacky |first=C |title=n-3 Fatty acids and the prevention of coronary atherosclerosis |journal=Am J Clin Nutr |volume=71 |issue=1 Suppl |pages=224S–7S |year=2000 |pmid=10617975 |doi=10.1093/ajcn/71.1.224s |doi-access=free}}</ref> Diets supplemented with cod liver oil have been demonstrated to have beneficial effects on [[psoriasis]],<ref>{{cite journal |pages=706–14 |doi=10.1111/j.1365-2133.2005.06781.x |title=Diet and psoriasis: experimental data and clinical evidence |year=2005 |last1=Wolters |first1=M. |s2cid=1426074 |journal=British Journal of Dermatology |volume=153 |issue=4 |pmid=16181450}}</ref> and daily supplementation has been shown to be correlated with lower rates of high-severity [[depression (mood)|depression]].<ref>{{cite journal |vauthors=Raeder MB, Steen VM, Vollset SE, Bjelland I |title=Associations between cod liver oil use and symptoms of depression: the Hordaland Health Study |journal=J Affect Disord |volume=101 |issue=1–3 |pages=245–9 |date=August 2007 |pmid=17184843 |doi=10.1016/j.jad.2006.11.006 }}</ref>

==Potential adverse effects==
[[File:All-trans-Retinol2.svg|thumb|[[Retinol]] (Vitamin A)]]
For vitamin A, a tablespoon (13.6 g) of cod liver oil contains 136% of the adult UL, 680% of the UL for children ages 1-3 years, and 453% of the UL for children ages 4-8 years. Even a teaspoon a day (1/3 of a tablespoon) exceeds the UL for children ages 1-8 years.<ref name="USDA"/> Vitamin A accumulates in the liver, and can reach harmful levels sufficient to cause [[hypervitaminosis A]].<ref name="lips2003" /> 

Reducing fatty acid oxidation and environmental toxin exposure requires purification processes as part of manufacturing of refined fish oil products.<ref name="bays2007">{{cite journal | author=Bays H E | title=Safety Considerations with Omega-3 Fatty Acid Therapy | volume=99 | journal=The American Journal of Cardiology | issue=6 (Supplement 1) | date=March 2007 | pages=S35–43 | doi=10.1016/j.amjcard.2006.11.020 | pmid=17368277}}</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.

In [[Tübingen]], Germany, drinking a glass of cod liver oil is the punishment for the participants in the last-place boat at the traditional [[:de:Stocherkahnrennen|Stocherkahnrennen]], an annual [[Punt (boat)|punting boat]] race.{{cn|date=April 2025}}

==See also==

* [[Dan Dale Alexander]]
* [[Shark liver oil]]

== References ==
{{Reflist}}

== External links ==

{{Commons category|Cod liver oil}}
* [https://www.britannica.com/topic/cod-liver-oil Cod liver oil] – ''[[Encyclopædia Britannica]]''

{{cod topics|state=expanded}}
{{Dietary supplement}}
{{Fats and oils}}
{{Authority control}}

{{DEFAULTSORT:Cod Liver Oil}}
[[Category:Animal fats]]
[[Category:Dietary supplements]]
[[Category:Fish products]]