• Bovine Cartilage, Shark Cartilage
Cartilage is a tough connective tissue found in many parts of the body. Your ears and nose are made from cartilage, and so is the gliding surface in your joints.
One constituent of cartilage, chondroitin , is widely used in Europe to treat osteoarthritis. Cartilage itself has also been proposed as a treatment for osteoarthritis.
The most commonly used forms of cartilage come from cows (bovine cartilage) and sharks. Provocative evidence had suggested that shark cartilage might have some value in the treatment of cancer. However, properly designed studies have so far failed to find benefit.
Unless your uncle works at a slaughterhouse or you're brave enough to prepare your own cartilage from whole sharks, the preferred source of cartilage is your healthfood store or pharmacy, where you can purchase this supplement in pill or powdered form.
Various doses of cartilage have been used in different studies, ranging from 2.5 mg to 60 g daily.
Based on the belief that sharks don't get cancer, shark cartilage has been heavily marketed as a cure for cancer . While this justification is a myth (sharks do get cancer), shark cartilage has, in fact, shown some promise for cancer treatment. Shark cartilage (like other forms of cartilage) contains substances that tend to inhibit angiogenesis (the growth of new blood vessels). Since cancers must build new blood vessels to feed themselves, this effect might be beneficial. Double-blind, placebo-controlled studies on special formulations of shark cartilage for the treatment of cancer are now underway. It has also been suggested that the anti-angiogenic properties of shark cartilage may make it helpful for psoriasis, but this hypothesis has not yet undergone proper study. 2
Shark cartilage also inhibits substances called matrix metalloproteases (MMPs). 1 These little-understood enzymes affect the "extracellular matrix," the framework of substances that lie between cells in the body. MMPs are thought to play a role in diseases of the cornea, gums, skin, blood vessels, and joints, as well as cancer and illnesses that involve excessive fibrous tissue. On this basis, shark cartilage has been proposed for a wide variety of medical conditions, from cataracts to scleroderma ; however, there are no meaningful studies as yet that can tell us whether it offers any benefit.
Cartilage in general has been proposed as a treatment for the common "wear and tear" type of arthritis known as osteoarthritis . The idea behind this is straightforward: Because osteoarthritis is a disease of the joints, and because cartilage is one of the elements that make up your joints, adding cartilage to the diet might help. This idea sounds a bit too simplistic to be believable, but it is the same principle behind the use of glucosamine and chondroitin (specific substances found in the joints) for osteoarthritis. Since well designed studies have found those treatments effective, perhaps cartilage itself will ultimately be proven to work. However, such studies of cartilage have not yet been performed.
What Is the Scientific Evidence for Cartilage?
A number of test tube experiments have found that shark cartilage extracts prevent new blood vessels from forming in chick embryos and other test systems. 4-9 As mentioned above, this effect could conceivably mean that shark cartilage might fight cancer . These findings have led to other test tube experiments , animal studies, and preliminary human trials to investigate the possible anticancer effects of shark cartilage. The results suggest that a particular liquid shark cartilage extract might be useful in the treatment of various cancers, including lung, prostate, and breast cancer.10-15 However, not all studies have been positive. 16,17
In any case, only double-blind, placebo-controlled trials can provide conclusive data. (For information on why such studies are essential, see Why Does This Database Rely on Double-blind Studies? ) So far, the only reported studies of this type on shark cartilage for cancer failed to find benefit. 19,20
Because cartilage is just common, ordinary gristle, it is presumably safe to consume. However, for reasons that are not at all clear at this time, there is a report of an individual who developed liver inflammation after taking shark cartilage supplements. 18 He recovered fully when the supplements were discontinued.
7. Oikawa T, Ashino-Fuse H, Shimamura M, et al. A novel angiogenic inhibitor derived from Japanese shark cartilage (I). Extraction and estimation of inhibitory activities toward tumor and embryonic angiogenesis. Cancer Lett. 1990;51:181-186.
8. McGuire TR, Kazakoff PW, Hoie EB, et al. Antiproliferative activity of shark cartilage with and without tumor necrosis factor-alpha in human umbilical vein endothelium. Pharmacotherapy. 1996;16:237-244.
11. Jamali M-A, Riviere M, Falardeau P, et al. Effect of AE-941 (neovastat), an angiogenesis inhibitor, in the Lewis lung carcinoma metastatic model, efficacy, toxicity prevention and survival. Clin Invest Med . 1998;(suppl):S16.
13. Riviere M, Alaoui-Jamali M, Falardeau P, et al. Neovastat: an inhibitor of angiogenesis with anti-cancer activity. Presented at: American Association for Cancer Research Annual Meeting 39; March 28-April 1, 1998; New Orleans, LA.
14. Blasecki J, Alaoui-Jamali M, Wang T, et al. Oral administration of Neovastat inhibits tumor progression in animal models of progressive tumor growth and metastasis. Int J Oncol . 1997;11(suppl):934.
15. Dupont E, Alaoui-Jamali M, Wang T, et al. Angiostatic and antitumoral activity of AE-941 (Neovastat), a molecular fraction derived from shark cartilage. Presented at: American Association for Cancer Research Annual Meeting 38; April 12-16, 1997; San Diego, CA.
20. Sussman, L. Shark cartilage shows no benefit as a therapeutic agent for lung cancer. EurekAlert! website. Available at: http://www.eurekalert.org/pub_releases/2007-06/uotm-scs060107.php. Accessed June 19, 2007.
Last reviewed October 2007 by EBSCO CAM Review Board
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