Shark cartilage

Shark cartilage is a dietary supplement made from the dried and powdered cartilage of a shark; that is, from the tough material that composes a shark's skeleton. Shark cartilage is marketed under a variety of brand names, including Carticin, Cartilade, or BeneFin, and is marketed explicitly or implicitly as a treatment or preventive for various illnesses including cancer.

There is no scientific evidence that shark cartilage is useful in treating or preventing cancer or other diseases. Controlled trials have shown no benefit to shark cartilage supplements, and shark cartilage contains potentially toxic compounds linked to Alzheimer disease and amyotrophic lateral sclerosis. However, shark cartilage supplements remain popular on the basis of the misconception that sharks do not get cancer, popularized in the 1992 best-selling book Sharks Don't Get Cancer.

Tumors of many kinds, some metastatic, have been found in numerous species of sharks. The first shark tumor was recorded in 1908. Scientists have since discovered 40 benign and cancerous tumors in 18 of the 1,168 species of sharks. Scarcity of studies on shark physiology has perhaps allowed the myth to be accepted as fact for so many years. Numerous cancers in sharks, including tumors in shark cartilage, were documented by Gary Ostrander and his colleagues from the University of Hawaii in research published in 2004.

While shark cartilage does not seem to be an effective treatment for cancer, some studies suggest that intake of one of its key components, chondroitin sulfate, may have positive effects on patients suffering from arthritis. That substance, however, is found in all animal cartilages, and not just that of sharks.

The ongoing consumption of shark cartilage supplements has been linked to a significant decline in shark populations, and the popularity of these supplements has been described as a triumph of pseudoscience and marketing over scientific evaluation.

Proponents of shark cartilage are encouraged by anecdotal evidence from users as to its efficacy. The proponents also cite studies that show that shark cartilage has had some success in preventing angiogenesis, the growth of new blood vessels from pre-existing vessels. While angiogenesis is often a normal function, it is also consistent with the growth of malignant tumors. They argue too, that very little research (in the quantity and quality of studies) has been conducted, and thus the benefits cannot be scientifically disputed.

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