This article is about the fish extract; for the traditional Newfoundland song, see "Cod Liver Oil (song)

Cod Liver Oil (song)

"Cod Liver Oil" is a song about a traditional medicinal drink for many Newfoundlanders. Cod liver oil in the traditional way of manufacture was sun cured and served in bottles in its raw form. The song was written by Johnny Burke , a balladeer from St. John's, Newfoundland...

".

Cod liver oil is a nutritional supplement

Dietary supplement

A dietary supplement, also known as food supplement or nutritional supplement, is a preparation intended to supplement the diet and provide nutrients, such as vitamins, minerals, fiber, fatty acids, or amino acids, that may be missing or may not be consumed in sufficient quantities in a person's diet...

 derived from liver of cod fish. It has high levels of the omega-3 fatty acids, EPA

Eicosapentaenoic acid

Eicosapentaenoic acid is an omega-3 fatty acid. In physiological literature, it is given the name 20:5. It also has the trivial name timnodonic acid...

 and DHA

Docosahexaenoic acid

Docosahexaenoic acid is an omega-3 fatty acid that is a primary structural component of the human brain and retina. In chemical structure, DHA is a carboxylic acid with a 22-carbon chain and six cis double bonds; the first double bond is located at the third carbon from the omega end...

, and very high levels of vitamin A

Vitamin A

Vitamin A is a vitamin that is needed by the retina of the eye in the form of a specific metabolite, the light-absorbing molecule retinal, that is necessary for both low-light and color vision...

 and vitamin D

Vitamin D

Vitamin D is a group of fat-soluble secosteroids. In humans, vitamin D is unique both because it functions as a prohormone and because the body can synthesize it when sun exposure is adequate ....

. It is widely taken to ease the symptoms of arthritis

Arthritis

Arthritis is a form of joint disorder that involves inflammation of one or more joints....

 and for other health benefits. It was once commonly given to child

Child

Biologically, a child is generally a human between the stages of birth and puberty. Some vernacular definitions of a child include the fetus, as being an unborn child. The legal definition of "child" generally refers to a minor, otherwise known as a person younger than the age of majority...

ren, because the high levels of vitamin D in cod liver oil have been shown to prevent rickets

Rickets

Rickets is a softening of bones in children due to deficiency or impaired metabolism of vitamin D, magnesium , phosphorus or calcium, potentially leading to fractures and deformity. Rickets is among the most frequent childhood diseases in many developing countries...

 and other symptoms of vitamin D deficiency

Hypovitaminosis D

Hypovitaminosis D is a deficiency of Vitamin D. It can result from: inadequate nutritional intake of vitamin D coupled with inadequate sunlight exposure , disorders that limit vitamin D absorption, and conditions that impair the conversion of vitamin D into active metabolites including certain...

.
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.