Shaun Ward MSc ANutr
Shark liver oil is (unsurprisingly) an oil that is obtained from the liver of sharks. These livers are very unique as they are incredibly large and full of oil which allows them to maintain their buoyancy. Deep sea sharks are even said to have livers that account for 5-10% of their total weight!
The oil has been consumed for centuries by our ancestors to promote would healing, and prevent respiratory tract and digestive issues.
In today’s world, shark liver oil is sold as a dietary supplement with increasingly popularity in certain countries such as Japan. It is mainly advertised to improve cardiovascular health, however there are also some other bold claims circulating the internet that it can treat cancer, HIV, swine flu, and radiation illness.
The main components of many shark liver oil are squalene (up to 90% of the oil) and pristane (up to nearly 8% of the oil).
The Potential Benefits of Shark Liver Oil
Below is a list of every potential benefit that's backed by credible scientific research:
It May Prevent Cardiovascular Disease
A substance within shark liver oil called squalene is thought to benefit cardiovascular health.
Shark liver oil is one of the only sources of squalene and is considered to be the richest source in the world . Squalene even received its name as a result of its initial identification from shark liver.
Chemically, squalene is a polyprenyl compound with close structural similarities to β-carotene (which converts to vitamin A), coenzyme Q10, and vitamins A, E and K.
Due to these similarities, shark liver oil has been speculated to exert similar metabolic effects to these essential compounds. Its specific link to cardiovascular health stems from the fact that vitamin E is important for decreasing arterial stiffening and preventing cardiovascular disease .
Direct evidence on shark liver oil is very limited, however a study has noted that 8 weeks of supplementation significantly decreased arterial stiffness and increased peripheral blood flow .
Lab experiments indicate that this may be because squalene is a unique antioxidant molecule that exhibits highly effective free radical scavenging activity .
There may also be some positive effects coming from the alkylglycerol content of shark liver oil due to its effect on immune and blood cell production .
Unfortunately there are no human studies to analyze whether this supplement has cardioprotective effects outside of animals, where it is thought to reduce free radical activity and lower inflammation .
It May Prevent Cancer
Shark liver oil contains alkylglycerols which have been associated with reducing tumor growth .
This is based on one study which showed that just 5 days of supplementation in animals has an anti-tumor effect, with a specific role given to the presence of alkylglycerols .
Current knowledge suggests that alkylglycerols in shark liver oil may work via a few different mechanisms:
- The inhibition of blood vessel formation in tumor tissue .
- Improving immunological defense systems .
- Anti-metastasis activity (stopping the spreading of cancer to other tissues) from its incorporation into membrane phospholipids .
However, despite the large claims, the current evidence base is scarce and there is not enough proof to suggest this supplement is a viable treatment option for cancer. Information or advertisements that say otherwise are misleading their audience .
Shark Liver Oil Safety And Side Effects
The safety of shark liver oil supplementation is a matter of concern.
Multiple shark liver oil supplements have been found to be contaminated with polychlorinated biphenyls (PCB’s) and polybrominated diphenyl ethers (PBDE’s) . This is important as PCB’s are a probable carcinogen in humans and are known to cause cancer in animals.
Shark liver oil and its components may also raise blood cholesterol levels.
However, these studies are only in animal populations and until the supplement is effectively and consistently tested in humans, its safety is unknown.
It is therefore recommended to avoid the consumption of shark liver oil, especially when considering its health benefits are not conclusive (better to be safe than sorry!).
Shark liver oil is a supplemental oil that is sourced from the liver of sharks.
There is a small amount of evidence in animal studies that the squalene and alkylglycerol components of the oil may help to prevent cardiovascular disease and cancer.
However, no research has been done in humans to see if these effects translate across species.
There is also a safety issue with shark liver oil consumption as it may have high concentrations of carcinogens called PCB’s and PBDE’s.