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Nutritional Supplements

There are a few shark products that are sold as nutritional supplements, many derived from shark cartilage and shark liver oil.

Shark cartilage is promoted as a remedy for arthritis and inflammation, and some companies’ claim that is has anti-cancer properties. More recently supplement companies have been marketing shark liver oil for its supposed immune system enhancing and anti-cancer properties. The anti-cancer claims are not proven and are disputed by the American Cancer Society, the FDA, Sloan- Kettering, Johns Hopkins University, and other reputable organizations. There are no reputable scientific studies demonstrating that shark cartilage supplements have any effect on immune function.

Interest was peaked by statements made in the book titled, "Sharks Don't Cancer" by William Lane. The book claimed that sharks don't get cancer and therefore taking shark cartilage pills will help to cure cancer in humans.

Sharks do get cancer and the claims are ludicrous, but still the book received a huge amount of media attention.

In 2000, however, the FTC ordered two companies to cease selling shark cartilage as a cure for cancer, and fined Lane Labs-USA, Inc. one million US dollars for false advertising in connection with shark cartilage sales. Yet still the myth continues. Most people have heard the false information that "sharks don't get cancer", but many fewer people know the truth.

Shark cartilage, the logic that started the fad: The use of shark cartilage (in the form of chondroitin sulfate) as a therapy for osteoarthritis started because cartilage has been found to suppress new blood vessel development, also why it has been the focus of cancer studies.  And where else do you go to get the most cartilage for your buck?  An animal made of the stuff - sharks!  It is not because shark's cartilage is any different, just that one shark has more than one cow.  The mainstay of the argument is also under evaluation because degenerating joints require the delivery of nutrients via blood vessels for repair so inhibiting blood flow to the area doesn't seem logical.

The effectiveness of shark cartilage has been called into question. In a study conducted in the New England Journal of Medicine on the effect of gulcosamine and chondroitin sulfate on patients with osteoarthritis in the knee found that "glucosamine and chondroitin sulfate alone or in combination did not reduce pain effectively in the overall group of patients" (Clegg et al. 2006).

In a study of the influence of information found on the world wide web on arthritis patients found that despite its prevalence online, shark cartilage "has (NOT) been proven to be beneficial for the treatment of arthritis.  Most of these therapies may be innocuous in their biological actions, but there are some concerns about the overall safety, in relation both to the expected contents of the product and to undeclared substances" (Suarez-Almazor et al 2001).

The European Food Safety Authority Scientific Opinion on the substantiation of health claims related to shark cartilage states "a cause and effect relationship has not been establishes between the consumption of shark cartilage and the maintenance of normal joints" (EFSA 2009, http://www.efsa.europa.eu/it/scdocs/doc/1269.pdf) The composition, potency, and purity are not checked by any outside authority.

Supplements do not need to be proven as safe or effective to be sold in the United States.

The National Institute of Health found virtually no information on the potential toxicity of chondroitin sulfate, no information on the manufacturing process, and no standard of guidelines (http://ntp.niehs.nih.gov/ntp/htdocs/chem_background/exsumpdf/chondroitin.pdf).

There have been cases of contamination of shark cartilage products. Researchers selected sources of chondroitin sulfate and determined that shark cartilage contained "too many other contaminants were excluded from consideration" (Barnhill et al. 2006).The FDA has recalled shark cartilage pills because of Salmonella contamination (http://www.fda.gov/oc/po/firmrecalls/nbty05_07.html and http://www.maryannaville.com/fda-reports-shark-cartilage-capsules-contaminated/ and http://www.food.gov.uk/news/newsarchive/2007/aug/shark - Salmonella detected in shark cartilage capsules from the United States (August 200).

There is a reference to the Korean FDA declaring high levels of Mercury and Cadmium in shark cartilage pills but cannot find the primary reference for that statement, however, 70 uncooked fins (i.e. cartilage) from a Hong Kong market, ¼ contained mercury concentrations well above the World Health Organization’s guidelines, enough to be identified as a significant threat to children and babies (Timms et al. 2009).

If you feel that chondroitin sulfate is something that will definitely help your condition, there are other sources from which it is derived.  A 2007 study found that shark cartilage produces the lowest amount of chondroitin sulfate compared to the other sources (Garnjanagoonchorn et al. 2007). You can search for bovine-only sources online.

Garnjanagoonchorn et al. (2007) also claim that the shark cartilage was a by-product of the shark fin soup restaurant so there is a clear link between that unsustainable and ecologically destructive practice and shark cartilage pills!

Shark Liver Oil

The oil from sharks’ livers has been used throughout histor by humans in many products such as food, cosmetics, textiles, pharmaceutical products, lubricants, and fuels (Vannuccini 1999). The oil is rich in omega-3 fatty acids and Vitamin A, properties important in the moisturizers and creams in which it can be found. Certain components of the oil (alklglycerols, squalamine, and squalene) have gained attention by cancer researchers. Alkylglycerols may stimulate immune cells and affect cell growth, squalamine may inhibit the growth of tumor blood vessels, and squalene may protect other cells.

Currently, there is no scientific evidence to support the claims that shark liver oil or its components are effective against cancer.

In fact, some supplements have been found to be contaminated with polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs), which are harmful to humans and may actually increase the risk of cancer (Akutsu et al. 2006). The quest for shark liver oil may be causing the decline of deep-sea sharks. Sharks living at extreme depths maintain neutral buoyancy by the oil in their large livers, making them a prime target for exploitation. However, these sharks are particularly vulnerable to overexploitation and population decreases because of very limited reproductive capabilities, even for sharks. 

References

Akutsu, K., Tanaka, Y., and Jayakawa, K. 2006. Occurrence of polybrominated diphenyl ethers and polychlorinated biphenyls in shark liver oil supplements. Food Additives and Contanminants, 23(12): 1323-1329.

Barnhill, J. G., Fye, C.L., Williams, D.W., Reda, D.J., Harris, C.L. and Clegg, D.O.  2006.  Chondroitin product selection for the glucosamine/chondroitin arthritis intervention trail.  Journal of the American Pharmacists Association, 46(1): 14-24 

Clegg, D.O., Reda, D.J., Harris, C.L., Klein, M.A., O’Dell, J.R., Hooper, M.M., Bradley, J.D., Bingham III, C.O., Weisman, M.H., Jackson, C.G., Lane, N.E., Cush, J.J., Moreland, L.W., Schumacher Jr., H.R., Oddis, C.V., Wolfe, F., Molitor, J.A., Yocum, D.E., Schnitzer, T.J., Furst, D.E., Sawitzke, A.D., Shi, H., Brandt, K.D., Moskowitz, R.W., and Williams, H.J.  2006.  Glucosamine, Chondroitin Sulfate, and the two in combination for painful knee osteoarthritis.  The New England Journal of Medicine, 354(8): 795-808.

Garnjanagoonchorn, W., Wongekalak, L., and Engkagul, A.  2007.  Determination of chondroitin sulfate from different sources of cartilage.  Chemical Engineering and Processing, 46: 465-471.

Suarez-Almazor, M.E., Kendall, C.J., and Dorgan, M. 2001. Surfing the Net — Information on the World Wide Web for Persons with Arthritis: Patient Empowerment or Patient Deceit? The Journal of Rheumatology 28(1): 185-191

Timms, T., L. Gonzalez, et al. (2009). In the Soup: how mercury poisons the fish we eat. S. Trent, WildAid.

Vannuccini, S.  1999.  Shark Utilization, Marketing and Trade.  FAO Fisheries Technical Paper 389, Rome, 470 pp.

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