Shark liver oil
Shark liver oil is an oil obtained from the livers of sharks. It has been used for centuries as a folk remedy to promote the healing of wounds and as a remedy for respiratory tract and digestive system problems. It is still promoted as a dietary supplement, and additional claims have been made that it can treat other maladies such as cancer, HIV, radiation illness, swine flu and the common cold. To date, none of these claims have 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 some hemorrhoid medications.
Many fish maintain buoyancy with swim bladders. 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 weight up to 20% of their total weight.
Medicinal use 
||This section needs more medical references for verification or relies too heavily on primary sources. (March 2013)|
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 being 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 biphenyls (PCBs) and polybrominated diphenyl ethers (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. Despite claims that the alkoxyglycerols 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, Bermudians rely on unique shark-oil based "barometers" to predict storms and other severe weather. Small bottles of oil are hung outside.
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- Bermuda Traditions & Their Sources
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