Shark liver oil is an oil obtained from the

liver The liver is a major organ only found in vertebrates which performs many essential biological functions such as detoxification of the organism, and the synthesis of proteins and biochemicals necessary for digestion and growth. In humans, it i ...

s of

shark Sharks are a group of elasmobranch fish characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified within the clade Selachi ...

s. It has been used for centuries as a

folk remedy Traditional medicine (also known as indigenous medicine or folk medicine) comprises medical aspects of traditional knowledge that developed over generations within the folk beliefs of various societies, including indigenous peoples, before the ...

to promote the healing of wounds and as a remedy for respiratory tract and digestive system problems.
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American Cancer Society The American Cancer Society (ACS) is a nationwide voluntary health organization dedicated to eliminating cancer. Established in 1913, the society is organized into six geographical regions of both medical and lay volunteers operating in more than ...

''. Retrieved 28 March 2013.Gupta P, K Singhal, AK Jangra, V Nautiyal and A Pandey (2012
"Shark liver oil: A review"
''Asian Journal of Pharmaceutical Education and Research'', 1 (2): 1-15. It is still promoted as a

dietary supplement A dietary supplement is a manufactured product intended to supplement one's diet by taking a pill, capsule, tablet, powder, or liquid. A supplement can provide nutrients either extracted from food sources or that are synthetic in order ...

, and additional claims have been made that it can treat other maladies such as cancer, HIV, radiation sickness,

swine flu Swine influenza is an infection caused by any of several types of swine influenza viruses. Swine influenza virus (SIV) or swine-origin influenza virus (S-OIV) refers to any strain of the influenza family of viruses that is endemic in pigs. As ...

, and the

common cold The common cold or the cold is a viral infectious disease of the upper respiratory tract that primarily affects the respiratory mucosa of the nose, throat, sinuses, and larynx. Signs and symptoms may appear fewer than two days after expos ...

.Shark liver oil
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WebMD WebMD is an American corporation known primarily as an online publisher of news and information pertaining to human health and well-being. The site includes information pertaining to drugs. It is one of the top healthcare websites. It was fou ...

''. Retrieved 28 March 2013. To date, none of these claims has been medically validated and shark liver oil (alone) is not a medication prescribed or utilized by American physicians. However, it is a component of some moisturizing skin lotions and

hemorrhoid Hemorrhoids (or haemorrhoids), also known as piles, are vascular structures in the anal canal. In their normal state, they are cushions that help with stool control. They become a disease when swollen or inflamed; the unqualified term ''he ...

medications.PE-shark liver oil-cocoa buttr Rect
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''. Retrieved 28 March 2013.

Function in the shark

Many fish maintain buoyancy with

swim bladder The swim bladder, gas bladder, fish maw, or air bladder is an internal gas-filled organ that contributes to the ability of many bony fish (but not cartilaginous fish) to control their buoyancy, and thus to stay at their current water depth wit ...

s. However sharks lack swim bladders, and maintain their buoyancy instead with large livers that are full of oil. This stored oil may also function as a nutrient when food is scarce. Deep sea sharks are usually targeted for their oil, because the livers of these species can account for up to 5–10% of their total weight.Vannuccini, Stefania (2002
Shark liver oil products
In: ''Shark Utilization, Marketing and Trade'', Fisheries Technical paper 389, FAO, Rome. .

Composition

A principal component of many shark oils is

squalene Squalene is an organic compound. It is a triterpenoid with the formula C30H50. It is a colourless oil, although impure samples appear yellow. It was originally obtained from shark liver oil (hence its name, as ''Squalus'' is a genus of sharks). A ...

, a

triterpenoid Triterpenes are a class of chemical compounds composed of three terpene units with the molecular formula C30H48; they may also be thought of as consisting of six isoprene units. Animals, plants and fungi all produce triterpenes, including squal ...

(C₃₀H₅₀), ranging up to 90% of the oil, depending on the species. In

Centrophorus ''Centrophorus'' is a genus of squaliform sharks. These deep-water sharks, found in temperate and tropical oceans throughout the world, are characterized by grey or brown bodies, large green eyes, and spines on both dorsal fins. These spines gi ...

species squalene may account for 15% of the total body weight. Pristane, another

terpenoid The terpenoids, also known as isoprenoids, are a class of naturally occurring organic chemicals derived from the 5-carbon compound isoprene and its derivatives called terpenes, diterpenes, etc. While sometimes used interchangeably with "terpenes" ...

(C₁₉H₄₀), is often a minor component, ranging up to nearly 8% of the oil.

Medicinal use

Most shark liver oil supplements have not been tested to find out if they interact with medicines, foods, or other herbs and supplements. Even though some reports of interactions and harmful effects may be published, full studies of interactions and effects are not often available. Although many people have taken shark liver oil, the issue of potential toxicity at the usual doses has not been well studied. Some mild digestive problems such as nausea, upset stomach, and diarrhea have been reported. The safe range of doses for shark liver oil has not yet been determined, though overdosing can have toxic consequences. Some animal studies have found that shark liver oil and its components may raise blood cholesterol levels. A Japanese study found some shark liver oil supplements to be contaminated with

polychlorinated biphenyl Polychlorinated biphenyls (PCBs) are highly carcinogenic chemical compounds, formerly used in industrial and consumer products, whose production was banned in the United States by the Toxic Substances Control Act of 1976, Toxic Substances Contro ...

s (PCBs) and

polybrominated diphenyl ethers Polybrominated diphenyl ethers or PBDEs, are a class of organobromine compounds that are used as flame retardants. Like other brominated flame retardants, PBDEs have been used in a wide array of products, including building materials, electronics, ...

(PBDEs). PCBs can have harmful effects in humans, and may increase the risk of some types of cancer. People with seafood allergies may also react to shark liver oil. Shark liver oil has been misleadingly promoted as a treatment for cancer. In addition, it has been confused with the word "Charcoal" in multiple translations. Despite claims that the

alkoxy In chemistry, the alkoxy group is an alkyl group which is singularly bonded to oxygen; thus . The range of alkoxy groups is vast, the simplest being methoxy (). An ethoxy group () is found in the organic compound ethyl phenyl ether (, also ...

glycerol Glycerol (), also called glycerine in British English and glycerin in American English, is a simple triol compound. It is a colorless, odorless, viscous liquid that is sweet-tasting and non-toxic. The glycerol backbone is found in lipids known ...

s derived from shark liver oil could reduce tumor growth, there is not sufficient evidence to prove this to be a viable treatment option.

Shark oil barometers

Traditionally, the people of Bermuda rely on shark-oil based "barometers" to predict storms and other severe weather. Small bottles of oil are hung outside. If the bottle is clear then the weather will be good, if it's cloudy then take cover. They are not true barometers, and how they work is disputed.Bermuda Traditions & Their Sources
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References

{{fatsandoils Animal fats Fish products Sharks

Function in the shark

Composition

Medicinal use

Shark oil barometers

See also

References