Chondroitin is a substance found in human and animal cartilage that is used to treat several physical disorders, most importantly arthritis, psoriasis , and cancer . It is the most plentiful type of glycosaminoglycan (GAG) found in cartilage. Glycosaminoglycans (GAGs) are complex carbohydrates that are found in the various types of connective tissue in the body. GAGs account for 5-20% of cartilage tissue. Chondroitin occurs in connective tissue as a sulfate composed of repeating disaccharide units; the first unit is either glucosamine or galactosamine; the other unit is glucuronic acid.
Chondroitin has been studied in humans for more than 30 years as a treatment for psoriasis, cancer, and arthritis. It is also used by veterinarians to treat animals for arthritis. These different applications are derived from different properties of chondroitin. More recently, chondroiton has been used in conjunction with another dietary supplement called glucosamine to help treat joint pain caused by osteoarthritis and to help stop cartilage loss in patients with the disease.
Studies have been conducted in the United States since 1990 to determine whether chondroitin from shark cartilage can speed up wound healing in psoriasis and related conditions. No conclusive findings have been reported.
The use of cartilage products to treat cancer is based on the popular belief that cartilaginous fish (sharks, skates, and rays) do not get cancer. Samples of these fish indicate, however, that they do in fact develop a variety of tumors, mostly soft-tissue cancers.
There are several theories as to why chondroitin and cartilage products containing it might be useful in treating cancer. One theory is that they slow down or stop the formation of blood vessels that supply the cancer with oxygen and nutrients. Another theory is that chondroitin blocks the formation of certain enzymes that tumors produce to invade surrounding tissue. The third theory suggests that cartilage products stimulate the immune system. As of late 1999 the National Cancer Institute was conducting a multicenter clinical trial of liquid cartilage extract.
Chondroitin is best known to the general public as a remedy for osteoarthritis, which is a form of arthritis caused by wearing away or degeneration of the cartilage that cushions the ends of bones. In particular, it is thought that the drying of cartilage tissue in osteoarthritis is a major cause of tissue destruction. Chondroitin sulfate is given together with glucosamine, a building block of GAGs. The chondroitin helps to attract and hold fluid within cartilage tissue. Tissue fluid keeps cartilage healthy in two ways: it acts as a shock absorber within the joints of the body, thus protecting cartilage from being worn away by the bones; and it carries nutrients to the cartilage. The cartilage in the joints of the human body has no blood vessels, so it must receive its nutrients from tissue fluid.
In addition to drawing tissue fluid into cartilage, chondroitin is also thought to protect cartilage by:
- Anti-inflammatory activity.
- Inhibiting the activity of enzymes that break down cartilage.
- Counteracting enzymes that interfere with the transport of nutrients to the cartilage.
- Stimulating the production of proteoglycans, glycosaminoglycans, and collagen. These complex molecules are the building blocks of new cartilage.
Several randomized double-blind studies of chondroitin in osteoarthritis patients were conducted in France and Italy in 1998. The European studies demonstrated that oral as well as injected chondroitin helps to increase joint mobility and reduce pain. A landmark 2001 study showed that combining glucosamine and chondroitin worked better than either alone in preventing cartilage damage and that both supplements worked well when taken orally.
The normal (non-vegetarian) adult diet already contains a certain amount of chondroitin; it is found in most animal tissues, particularly the gristle attached to bones.
Chondroitin sulfate can be taken orally as a pill, powder, or liquid. It can also be administered by injection. Oral preparations of chondroitin, alone or in combination with glucosamine, are available in the United States as over-the-counter (OTC) dietary supplements. They can be purchased over the internet, at pharmacies, health food stores, or even some grocery stores. Because they are marketed as dietary supplements, they do not require testing or approval by the Food and Drug Administration (FDA). At present, there are no specific quality control requirements or good manufacturing process (GMP) standards for these products.
There are at present no standard patterns of administration for chondroitin as a treatment for psoriasis or cancer. When chondroitin is used together with glucosamine as a treatment for osteoarthritis, the daily dosage is based on the patient's weight. Suggested dosages are: 1000 mg glucosamine + 800 mg chondroitin sulfate for 120 lbs or less; 1500 mg glucosamine + 1200 mg chondroitin sulfate for 120-200 lbs; and 2000 mg glucosamine + 1600 mg chondroitin sulfate for greater than 200 lbs.
For maximum effectiveness, patients are advised to divide their daily dosage into 2 to 4 doses and take them throughout the day with food. They are also encouraged to take vitamin C and manganese supplements since these substances appear to increase the effectiveness of the chondroitin.
There are two important precautions to take regarding chondroitin as a dietary supplement for osteoarthritis. The first is to avoid self diagnosing and self medicating. Persons with stiff or sore joints should consult a medical doctor (M.D.), osteopathic physician (D.O.), or naturopathic physician (N.D.) for an evaluation to be sure that the problem is indeed osteoarthritis. Gout, bursitis, rheumatoid arthritis, fibromyalgia , and several other conditions can also cause pain and stiffness in the joints. These conditions are not helped by chondroitin. The supplement has not been studied in children or in pregnant or nursing women.
The second precaution is to purchase chondroitin made by a reliable manufacturer. The lack of government regulation of products sold as dietary supplements means that that there is no guarantee that claims made on the label are accurate. Thus a product that claims to contain chondroitin may not actually contain it, may not contain the amount that it claims to, or may not be free from contamination and safe to use. One helpful guideline is to look for the words pharmaceutical grade on the label. This standard ensures that the product is pure and that it contains the stated amount of chondroitin. A table of laboratory-tested chondroitin or glucosamine/chondroitin products and their manufacturers can be found in The Arthritis Cure by Jason Theodosakis, et al. listed in the resources section below.
With regard to potential overdose problems, chondroitin sulfate appears to be nontoxic. One six-year study of people taking doses of 1.5-10 grams per day of chondroitin found no toxicity in the subjects.
Chondroitin sulfate has no known significant side effects. Some people report having a bad taste in the mouth or mild nausea when taking large doses of oral chondroitin on an empty stomach. Gas or bloating has also been reported. A few people who have received chondroitin by injection report a mild soreness around the injection site.
Chondroitin sulfate is not known to cause any significant interactions with other medications. A paper presented at the 1999 annual meeting of the American Academy of Orthopaedic Surgeons, however, suggests that because the chondroitin sulfate molecule is similar to the heparin molecule, its use together with anticoagulant drugs is questionable.
Paulsen, Douglas F., PhD. Basic Histology: Examination and Board Review. Norwalk, CT: Appleton & Lange, 1990.
Theodosakis, Jason, MD, MS, MPH; Brenda Adderley, MHA; and Barry Fox, PhD. The Arthritis Cure. New York: St. Martin's Press, 1997.
Theodosakis, Jason. "Relief for your Painful Joints (Wellness)." Better Nutrition (May 2002):32.
National Cancer Institute Cancer Information Service (CIS). (800) 4-CANCER. TTY: (800) 332-8615. http://www.cancernet.nci.nih.gov.
NIH National Center for Complementary and Alternative Medicine (NCCAM). NCCAM Clearinghouse, P. O. 8218, Silver Spring, MD 20907-8218. TTY/TDY: (888) 644-6226.
Schenck, Robert C., Jr., MD. Oral Chondroitin Sulfate and Glucosamine Therapy of Arthritis. Paper presented at the 1999 annual meeting of the American Academy of Orthopaedic Surgeons. February 5, 1999.
Rebecca J. Frey, PhD
Teresa G. Odle
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