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Shark Cartilage and Cancer
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| Angiogeneis is the process of developing new blood vessels that deliver nutrients to cells necessary for the growth of tumours. Cartilage is said to have anti-angiogenic properties as it contains substances that inhibit angiogenesis. |
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The promotion of cartilage to treat cancer has arisen from the false claim that sharks, which have cartil aginous skeletons, do not suffer from cancer. Cartilage naturally has few blood vessels, and cartilage from all species rarely develops malignant tumours; this appears to be due to substances in cartilage inhibiting angiogenesis (see box for explanation [1]) . Consequently, claims have arisen that solid forms of shark cartilage may be efficient in the treatment of human cancer. Several studies over the last 30 years have attempted to assess the effect of cartilage in cancer treatment. Most of these studies have been viewed with scepticism due to a lack of rigorous trials, and in rare cases where a significant number of patients were involved in a trial, no consistent improvement was observed [2].
Two large glycoproteins (sphyrnastatin 1 and 2), identified in hammerhead shark cartilage, have been found to have anti-angiogenic properties that could in theory be helpful in the treatment of cancer [3] . However, large glycoproteins are normally broken down in the body, rather than absorbed, so they are unlikely to reach the bloodstream when cartilage is administered orally. Furthermore, commercially available supplements contain varying amounts of cartilage, and contain binding agents that do not have anti-angiogenic properties [4]. The potential for the active components of cartilage to inhibit angiogenesis in human cancers depends on whether their biological activity can be preserved following their extraction, and used in a treatment that delivers an effective concentration of the active substance to target tissues [2].
To date only one extract – AE-941 (Neovastat), which was developed as a pharmaceutical and is NOT a commercially available supplement – has been through both laboratory trials and clinical in-patient trials, with the following result: “In the first study of its kind, shark cartilage extract, AE-941 or Neovastat, has shown no benefit as a therapeutic agent when combined with chemotherapy and radiation for patients with advanced non-small cell lung cancer” [5]. In short, no scientific studies by independent researchers using proper controls have been able to substantiate claims that shark cartilage supplements are effective in treating human cancer. Similarly, there is no published experimental data to suggest unprocessed shark cartilage supplements are effective in the plethora of other conditions that they are used to treat.
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What is Shark Cartilage?
Processing, trade and markets
Shark conservation
References
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