According to Constantine Alifrangis and Justin Stebbing, two well-respected doctors of cancer medicine from Imperial College London in the United Kingdom, the ability of the general public to access information regarding the effectiveness of integrative medicine and dietary supplements is hindered by limited availability of peer-reviewed journals.
Peer-review is the method by which information about clinical trials is evaluated by unbiased experts in the field to determine if the data was collected and evaluated properly before it is published. The peer-review process is used in the scientific community to try to ensure that published data has been collected using appropriate intellectual rigor and standards.
Due to the limited availability of many peer-reviewed journals and the widespread availability of other unregulated sources of information such as the internet, much of the general public is not able to distinguish between high and low quality sources of information.
Alifrangis and Stebbing describe the controversy regarding the effects of shark cartilage as an example of this problem. Shark cartilage has become one of the most commonly recognized supplements in the United States, with more than 40 brand-name products sold in 1995 alone. Primarily used by patients to treat cancer, shark cartilage became popular in the 1980s after several poorly conducted case series reported "miracle" cancer cures.
Early theories regarding the use of shark cartilage for cancer originated from the belief that sharks are not afflicted by cancer. In particular, the cartilaginous skeleton of the Pacific spiny dogfish shark was thought to provide a naturally occurring substance that protects the animal from metastatic (spreading) disease. However, contrary to initial reports, sharks can be afflicted by cancer.
Commercial shark cartilage is primarily composed of chondroitin sulfate (a type of glycosaminoglycan), which is further broken down to glucosamine and other end products. Although chondroitin and glucosamine have been very well-studied for osteoarthritis, there is currently a lack of evidence supporting the use of unprocessed shark cartilage preparations for this indication. Shark cartilage also contains an abundant supply of calcium (up to 600-780 milligrams of elemental calcium per daily dose). Manufacturers sometimes promote its use for calcium supplementation rather than for its purported anti-cancer effects. Other trace elements that are found in shark cartilage in higher amounts than those in other fish and in other animal bones include iron, zinc, selenium, copper, manganese, molybdenum, titanium and strontium.
Monthly expenditures on shark cartilage can be as much as $700-$1,000. Furthermore, many trials regarding the use of shark cartilage have been funded by its manufacturers, which raises questions about bias.
According to Alifrangis and Stebbing, doctors should be aware of which types of integrative medicine and dietary supplements have been shown to be effective versus which products have been popularized without supportive scientific evidence. They should take time to share this information with their patients to ensure that all individuals are able to make informed decisions regarding their care. Furthermore, the authors propose that each issue of peer-reviewed journals be made available, free of charge, for the first six months after publication. They believe this could allow more people in the general public to access strong scientific data to make better informed decisions.
For more information about shark cartilage and other integrative therapies, please visit Natural Standard's Foods, Herbs & Supplements Database.