Shark Cartilage: Research Status

Townsend Letter for Doctors and Patients,  Oct, 2001  by Stephen Holt

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The Shark Cartilage Renaissance

A decade ago, shark cartilage became the focus of intense public interest, concerning its use as a dietary supplement for the nutritional support of cancer and arthritis. Amidst hyperbolic claims of efficacy, shark cartilage became the most popular alternative treatment for cancer, since the laetrile controversy. Earlier basic science experiments had shown conclusively that shark cartilage was a natural source of compounds with promising biopharmaceutical potential. In particular, solid-dosage, shark cartilage prepared in the form of Cartilade[R] (a leading brand recently acquired by Atrium Biotech USA,) was shown to be antiangiogenic (interfering with new blood vessel growth) in laboratory experiments, with possible antiangiogenic effects in humans and animals.

Marketing "hype" that was applied to shark cartilage confused public opinion and interfered with the serious quest for the identification and characterization of bioactive components of shark cartilage. Early claims that solid dose shark cartilage was an effective "panacea" cure for cancer were not confirmed in follow-up studies. More recently, well-controlled scientific experiments conducted by a Canadian laboratory indicate that shark cartilage contains potent antiangiogenic compounds, that can be extracted using special patented techniques leading to a much more concentrated and therefore effective antiangiogenic product. These hydrosoluble extracts of shark cartilage have been shown to exert powerful antiangiogenic effects, both in vivo and in vitro. Shark cartilage has re-emerged as an important biological agent which may control unwanted blood vessel growth, that contributes to many common, chronic, degenerative diseases.

The Antiangiogenesis Debate: The Importance of MMP

Through forty years of research, cartilage of various origins (chicken, bovine and shark) has been studied extensively and many of its active components have been recently identified. Several mechanisms have been proposed as to how oral shark cartilage supplements work on the body, which may explain its beneficial effects on several diseases including its effects on skeletal diseases. The mechanisms of action of shark cartilage include its effects on angiogenesis and immune modulation. Of particular importance is the discovery of the ability of the shark cartilage extract CarTCell[R] to inhibit enzymes that are responsible for the breakdown of supporting tissues (tissue matrix). These enzymes (matrix metalloproteinases, MMP) are responsible for the breakdown of blood vessel walls leading to new blood vessel formation (angiogenesis). Shark cartilage contains powerful inhibitors of MMP (anti-MMP) and it is a source of inhibitors of new blood vessel formation (antiangiogenic effect).

Angiogenesis is a complex process leading to formation of new blood vessels. The rationale for the use of shark cartilage in several disease states has been largely based on the hypothesis that cartilage administered to animals and humans in varying formats and dosages by a variety of routes may exert an antiangiogenic effect. Angiogenesis (the growth of new blood vessels) is an underlying mechanism that is associated with a variety of diseases, including: cancer, arthritis, proliferative retinopathy, neovascular glaucoma and skin diseases, such as psoriasis (Table 1). Overall review of available scientific information leads many nutritionists and scientists to believe that the solid form is suitable for less severe conditions where angiogenesis plays a pathophysiologic role while the liquid extract which concentrates the active antiangiogenic components, should be favored in more severe conditions associated with vascular proliferation.

Bioactive Components of Shark Cartilage

Shark cartilage is a natural product that should be manufactured by techniques that result in high-quality, palatable, active nutrient compounds. Failure to conform to standards of manufacture and quality assurance results in the production of shark cartilage supplements with uncertain biological effects. The retention of biological integrity of shark material during processing of shark cartilage is a key issue. The only brand of shark cartilage powder that has been subjected to repeated clinical trials and laboratory investigations over the past decade is the Cartilade brand of shark cartilage, while CarTCell[R] is the only liquid extract to have demonstrated significant inhibition of angiogenesis in a double-blind, placebo controlled human study. Although shark cartilage is available for purchase in various formulations, produced by a variety of techniques, the biological effects of solid-dose, shark cartilage brands other than Cartilade are often in question. Some manufacturers have produced limited quali tative data on their product, but few have subjected their product to clear quantitative analysis or to laboratory or clinical research. In particular, claims that brands of solid dose shark cartilage, other than Cartilade are antiangiogenic have not been supported by published information.