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==Adverse effects==
==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.
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. *** THIS STATEMENT IS WRONG! ONLY SYNTHETIC VITAMIN A, SUCH AS FOUND IN VITAMIN PILL SUPPLEMENTS, IS TOXIC IN HIGH DOSES.


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>
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>

Revision as of 19:01, 10 October 2008

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 nutritional supplement derived from liver of cod fish. It has high levels of the omega-3 fatty acids, EPA and 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 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 oils, which are extracted from the cooked whole body 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,[1] but has also been clinically proven to have a positive effect on heart,[2][3] bone,[4] and brain,[5] as well as helping to nourish skin,[6] 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 do not meet the RDA for Vitamin D.[7][8][9][10]

Cod liver oil is effective in treatment of household burns, due to its high vitamin content, often leaving no burn-related blister.[citation needed]

Cod liver oil has been listed by some[11] as an effective complementary measure for long-term treatment of Multiple Sclerosis, a sometimes disabling autoimmune disease of the human central nervous system.

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.[12]

Use of cod liver oil during pregnancy is associated with lower risk of Type I diabetes in the offspring.[13] 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.[14] 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. *** THIS STATEMENT IS WRONG! ONLY SYNTHETIC VITAMIN A, SUCH AS FOUND IN VITAMIN PILL SUPPLEMENTS, IS TOXIC IN HIGH DOSES.

The risks of hypervitaminosis and of exposure to environmental toxins such as mercury, polychlorinated biphenyls, 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.[15]

A high intake of cod liver oil by pregnant women is associated with a nearly five-fold increased risk of gestational hypertension,[16] although this study did not control for mercury, which can be present in harmful amounts in fish[15] and which is another cause of hypertension.[17]

Some urge caution when taking cod liver oil and other fish-based supplements since they may contain elevated levels of toxins such as mercury and PCBs found in fish.[15] 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.[18]

Other uses

In 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

References

  1. ^ Gruenwald J, Graubaum HJ, Harde A. Effect of cod liver oil on symptoms of rheumatoid arthritis. 2002. Adv Ther 19:101-107. PMID 12069368
  2. ^ 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. {{cite journal}}: |pages= has extra text (help); Explicit use of et al. in: |first= (help)
  3. ^ von Schacky, C. (2000). "n-3 Fatty acids and the prevention of coronary atherosclerosis". Am J Clin Nutr. 71 ((1 Suppl)): 224S–7S.
  4. ^ Akpede, GO; et al. (1999). "Rickets and deprivation: a Nigerian study". J R.Soc.Health. 119: 216–22. {{cite journal}}: Explicit use of et al. in: |first= (help)
  5. ^ "Cod liver oil, fish oil and Omega 3, "Cod liver oil and depression"".
  6. ^ 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: 15–20. {{cite journal}}: Explicit use of et al. in: |first= (help)
  7. ^ Reginster JY. The high prevalence of inadequate serum vitamin D levels and implications for bone health. 2005. Curr Med Res Opin 21:579-586. DOI: 10.1185/030079905X41435 PMID 15899107
  8. ^ 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 full text (free)
  9. ^ Peterlik M, Cross HS. Vitamin D and calcium deficits predispose for multiple chronic diseases. 2005. Eur J Clin Invest 35:290-304. DOI: 10.1111/j.1365-2362.2005.01487.x PMID 15860041
  10. ^ 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 full text (free)
  11. ^ Swank, Roy L., and Barbara Brewer Duggan. The Multiple Sclerosis Diet Book: A Low-Fat Diet for The Treatment of MS. Doubleday, 1987.
  12. ^ Garland CF, Garland FC, Gorham ED, et al. The role of vitamin D in cancer prevention. 2006. Am J Public Health 96:252-261. DOI: 10.2105/AJPH.2004.045260 PMID 16380576
  13. ^ 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. DOI: 10.1007/s001250051499 PMID 11043854 full-text (free)
  14. ^ Paul Lips (2003-05-08). "Hypervitaminosis A and fractures". N Engl J Med. 348: 1927–1928. Retrieved 2008-03-06.
  15. ^ a b c Bays H E (2007-03-19). "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.
  16. ^ 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. DOI: 10.1111/j.1471-0528.2006.00826.x PMID 16487202
  17. ^ Horowitz Y, Greenberg D, Ling G, Lifshitz M. Acrodynia: a case report of two siblings. Arch Dis Child 2002; 86: 453. PMID 12023189
  18. ^ ConsumerLab.com - Omega-3 Fatty Acids (EPA and DHA) from Fish/Marine Oils review
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