Cartilage is a type of connective tissue consisting of cells called chondrocytes and a tough, flexible matrix made of collagen, protein, and sugar. Most cartilage is converted to bone as an animal matures, but some cartilage remains in the nose and ears, as well as joints such as the knees, hips, shoulders, and fingers.
Bovine cartilage (cartilage derived from cows) and shark cartilage have been investigated for many years as treatments for cancer, psoriasis, arthritis, and a number of other medical conditions. The interest in cartilage as a treatment for cancer arose, at least in part, from the mistaken belief that sharks (whose skeletons consist primarily of cartilage) are not affected by cancer. This assumption proved to be untrue, however, and studies in humans have yet to demonstrate that shark cartilage reverses, prevents, or even slows cancerous tumor growth.
Claims that cartilage may be of some medical value date back to 1954. Laboratory studies have reported that substances in cartilage (particularly shark cartilage) may reduce inflammation associated with arthritis (including rheumatoid arthritis), stimulate the immune system, and relieve pain. Whether these beneficial properties apply to people has not been proven in scientific studies. Cartilage does appear to provide some benefits for the following health conditions:
Psoriasis
Preliminary clinical evidence suggests that extracts of shark cartilage may reduce inflammation from psoriasis (a skin disorder that appears as raised, reddish-pink areas covered with silvery scales and red borders).
Osteoarthritis
Two components of cartilage, glucosamine and chondroitin (although not specifically cartilage supplements), have been shown to decrease pain, improve range of motion, reduce swelling, enhance walking pace, and slow the progression of osteoarthritis (not rheumatoid arthritis, an autoimmune condition) in some types of patients. Further studies are currently underway to determine if these supplements are safe and effective when taken for long periods of time.
Cancer
Despite a lack of substantial scientific evidence, shark cartilage has also been widely used as an alternative treatment for cancer. Because cartilage cells do not have any blood vessels, some researchers speculate that they produce substances that inhibit blood vessel formation. Cancerous tumors rely on blood vessels to survive because blood provides oxygen and nutrients necessary for their growth. The possibility that cartilage could stop the formation of blood vessels and "starve" cancerous tumors of necessary oxygen and nutrients has led to theories regarding the use of this supplement as a treatment for cancer.
Although many clinical studies have been conducted on cartilage as a treatment for cancer, only a few have been published in scientific journals and none have reported any benefit in using cartilage supplements for cancer (including breast, colon, lung, prostate, brain, and lymphoma). According to the National Cancer Institute (NCI), the evidence so far is inconclusive regarding the effectiveness of cartilage as a cancer treatment in humans. In fact, the NCI halted their own research regarding cartilage supplementation because all of the preparations were contaminated, and the Federal Trade Commission (FTC) has taken legal action against several companies selling cartilage products as a "cancer cure."
Because of the potential for side effects and possible interactions with medications, dietary supplements should be taken only under the supervision of a knowledgeable health care provider.
Shark and bovine cartilage should always be purchased from a reputable manufacturer to reduce the risk of contamination. Labels should be checked carefully. Only supplements that contain 100% pure shark cartilage should be purchased.
There has been at least one case of hepatitis reported from taking shark cartilage.
Pregnant and breastfeeding women, children, and individuals recovering from surgery or a heart attack should not take cartilage supplements.
Cartilage should never be used as a substitute for conventional cancer therapies.
Shark cartilage products may contain high levels of calcium, which may be harmful to patients with kidney disease, abnormal heart rhythms, a tendency to form kidney stones, and those with cancers that raise calcium levels.
Shark cartilage may lower blood sugar levels. Caution is advised in patients with diabetes or hypoglycemia, and in those taking drugs, herbs, or supplements that affect blood sugar. Serum glucose levels may need to be monitored by a health care provider, and medication adjustments may be necessary.
Acidic fruit juices, such as apple, grape, or cranberry, may reduce the absorption of shark cartilage taken by mouth.
If you are currently being treated with any of the following medications, you should not use cartilage supplements without first talking to your health care provider.
Thiazide diuretics -- Cartilage contains high amounts of calcium. Thiazide diuretics, such as hydrochlorothiazide, can raise calcium levels in the blood. Therefore, using cartilage supplements together with this type of diuretic could lead to dangerously high levels of calcium.
Blood sugar lowering medications and insulin -- Shark cartilage may lower blood sugar levels, potentially decreasing the amount of blood sugar lowering medications or insulin needed. Use shark cartilage only under the supervision of a health care provider if you take blood sugar lowering medications or insulin.
Cremer MA, Rosloniec EF, Kang AH. The cartilage collagens: A review of their structure, organization, and role in the pathogenesis of experimental arthritis in animals and in human rheumatic disease. J Mol Med. 1998;76:275-288.
da Camara CC, Dowless GV. Glucosamine sulfate for osteoarthritis. Ann Pharmacother. 1998;32:580-587.
Das A, Hammad TA. Combination of glucosamine and chondroitin in knee OA. Osteoarthritis Cartilage. 2000;8(5):343-350.
Deal CL, Moskowitz RW. Nutraceuticals as therapeutic agents in osteoarthritis: the role of glucosamine, chondroitin sulfate, and collagen hydrolysate. Rheum Dis Clin North Am. 1999;25(2):379-395.
Delafuente JC. Glucosamine in the treatment of osteoarthritis. Rheum Dis Clin North Am. 2000;26(1):1-11.
Dupont E, Savard PE, Jourdain C, et al. Antiangiogenic properties of a novel shark cartilage extract: potential role in the treatment of psoriasis. J Cutan Med Surg. 1998;2:146–152.
Ernst E. A primer of complementary and alternative medicine commonly used by cancer patients. Med J Aust. 2001;174:88-92.
Ernst E, Cassileth BR. How useful are unconventional cancer treatments? Eur J Can. 1999;35(11):1608-1613.
Federal Trade Commission. "Operation Cure.all" nets shark cartilage promoters: two companies charged with making false and unsubstantiated claims for their shark cartilage and skin cream as cancer treatments. June 29, 2000.
Fontenele JB, Araujo GB, de Alencar JW, Viana GS. The analgesic and anti-inflammatory effects of shark cartilage are due to a peptide molecule and are nitric oxide (NO) system dependent. Biol Pharm Bull. 1997;20(11):1151-1154.
Gonzalez RP, Leyva A, Moraes MO. Shark cartilage as a source of antiangiogenic compounds: from basic to clinical research. Biological and Pharmaceutical Bulletin. 2001;24(10):1097-1101.
Gottlieb MS. Conservative management of spinal osteoarthritis with glucosamine sulfate and chiropractic treatment. [Review]. J Manipulative Physiol Ther. 1997;20(6):400-414.
Horsman MR, Alsner J, Overgaard J. The effect of shark cartilage extracts on the growth and metastatic spread of the SCCVII carcinoma. Acta Oncol. 1998;37:441–445.
Leeb BF, Schweitzer KM, Smolen JS. A metaanalysis of chondroitin sulfate in the treatment of osteoarthritis. J Rheumatol. 2000;27(1):205-211.
Loprinzi CL, Levitt R, Barton DL, et al., Evaluation of shark cartilage in patients with advanced cancer: a North Central Cancer Treatment Group trial. Cancer. 2005;104(1):176-82.
Matsumoto T, Tsurumoto T. Serum YKL-40 levels in rheumatoid arthritis: correlations between clinical and laboratory parameters. Clin Exp Rheumatol. 2001;19(6):655-660.
McAlindon T. Glucosamine for osteoarthritis: dawn of a new era? Lancet. 2001;357:247.
McAlindon TE, LaValley MP, Gulin JP, Felson DT. Glucosamine and chondroitin for treatment of osteoarthritis: a systematic quality assessment and meta-analysis. JAMA. 2000;283(11):1469-1475.
Merly L, Simjee S, Smith SL. Induction of inflammatory cytokines by cartilage extracts. IntImmunopharmacol. 2007;7(3):383-91.
Miller DR, Anderson GT, Stark JJ, Granick JL, Richardson D. Phase I/II trial of the safety and efficacy of shark cartilage in the treatment of advanced cancer. J Clin Oncol. 1998;16:3649–3655.
Ratel D, Glazier G, Provencal M, Boivin D, Beaulieu E, Gingras D, Beliveau R. Direct-acting fibrinolytic enzymes in shark cartilage extract: potential therapeutic role in vascular disorders. Thromb Res. 2005;115(1-2):143-52.
Reginster JY, Deroisy R, Rovati LC, et al. Long-term effects of glucosamine sulphate on osteoarthritis progression: a randomised, placebo-controlled clinical trial. Lancet. 2001;357:251-256.
Romano CF, Lipton A, Harvey HA, Simmonds MA, Romano PJ, Imboden SL. A phase II study of Catrix-S in solid tumors. J Biol Response Mod. 1985;4:585–589.
Sheu JR, Fu CC, Tsai Ml, Chung WJ. Effect of U-995, a potent shark cartilage-derived angiogenesis inhibitor, on anti-angiogenesis and anti-tumor activities. Anticancer Res. 1998;18:4435–4441.
Towheed TE, Anastassiades TP. Glucosamine and chondroitin for treating symptoms of osteoarthritis: evidence is widely touted but incomplete. JAMA. 2000;283(11);1483-1484.
