Overview:

Chondroitin is a molecule that occurs naturally in the body. It is a major component of cartilage -- the tough, connective tissue that cushions the joints. Chondroitin helps to keep cartilage healthy by absorbing fluid (particularly water) into the connective tissue. It may also block enzymes that break down cartilage, and it provides the building blocks for the body to produce new cartilage.

A number of scientific studies suggest that chondroitin may be an effective treatment for osteoarthritis (OA). OA is a type of arthritis characterized by the breakdown and eventual loss of cartilage, either due to injury or to normal wear and tear. It commonly occurs as people age. In some studies, chondroitin supplements have decreased the pain of OA. Not all studies are positive, though, and several recent ones have not shown any positive effect from taking chondroitin. It's not clear why the studies have different findings, and experts disagree on whether chondroitin is helpful in treating OA.

In the past, some researchers thought chondroitin may actually slow progression of the disease, unlike other current medical treatments for OA. (Many people take either acetaminophen or nonsteroidal anti-inflammatory drugs, such as ibuprofen and naproxen, for OA pain). But so far studies have not shown conclusively that chondroitin helps repair or grow new cartilage, or stops cartilage from being further damaged. Chondroitin is often taken with glucosamine, another supplement that has been studied along with chondroitin for OA. Like chondroitin, glucosamine also has conflicting results.

Therapeutic Uses:

Treatment

Osteoarthritis

Results from several well-designed scientific studies suggest that chondroitin supplements may be an effective treatment for OA, particularly OA of the knee or hip. In general, findings from these studies suggest that chondroitin:

• Reduces OA pain
• Improves functional status of people with hip or knee OA
• Reduces joint swelling and stiffness
• Provides relief from OA symptoms for up to 3 months after treatment is stopped

However, the largest clinical trial so far, the 2006 Glucosamine/Chondroitin Arthritis Intervention Trial (GAIT), sponsored by the National Institutes of Health, showed conflicting and somewhat confusing results. The study of about 1,600 people with OA of the knee found that glucosamine and chondroitin did not reduce pain in the overall group, although it did appear to lessen pain among those with moderate-to-severe OA of the knee. The study has raised questions for further research. Since glucosamine and chondroitin were combined in this study, it is not possible to determine the effect of chondroitin alone. In addition, researchers are now studying whether the glucosamine-chondroitin combination may in fact help those with more severe OA.

A second phase of the study in 2008 looked at some participants who continued with the study for another 28 months. They were tested to see whether glucosamine or chondroitin (together or alone) slowed the loss of cartilage in their knees. They showed no difference in cartilage loss compared with people who took placebo. But all groups -- those taking placebo, those taking both supplements, and those taking only one supplement -- lost less cartilage than expected.

Results continued to be mixed. One recent analysis of a number of studies found smaller trials tended to find that chondroitin was effective, while larger, more thorough studies tended to find that it wasn't.

Most studies have shown that chondroitin needs to be taken for 2 - 4 months before it shows effectiveness, although some improvement may be experienced sooner. Glucosamine and chondroitin can be used along with NSAIDs to treat OA.

Bladder Conditions

One study found that intravesicular chondroitin (irrigating the bladder with chondroitin) may help relieve symptoms of interstitial cystitis. Another single study found that chondroitin, taken orally, might help reduce symptoms of overactive bladder.

Other

Other conditions for which chondroitin has been suggested include preterm labor, Alzheimer's disease, heart disease, and osteoporosis. However, no studies have yet evaluated these claims.

Dietary Sources:

There are no major dietary sources of chondroitin, so people who want to take it must take supplements.

Dosage and Administration:

Chondroitin is commonly sold as chondroitin sulfate, in capsules or tablets. It is often combined with glucosamine and sometimes manganese as well. Manganese is a trace element necessary for normal bone health. The total amount of manganese from foods and supplements should not exceed 11 mg per day, but several combination supplements for arthritis (containing glucosamine, chondroitin, and manganese) have more than that. Read labels carefully, and consider choosing a supplement without manganese.

Pediatric

Chondroitin is not recommended for children. It is mainly used for treatment of osteoarthritis (a condition that affects adults), and its safety for children has not been studied.

Adult

400 mg three times a day or 600 mg two times a day, taken by mouth.

Precautions:

In the past, researchers have found that some chondroitin supplements did not contain the amount of chondroitin stated on the label. The same was true of some combination glucosamine and chondroitin supplements. Ask your doctor to recommend a brand, or choose a brand you trust.

Many chondroitin supplements are made from cow cartilage. If you are a vegetarian, look for a supplement made from algae instead.

Side Effects

Chondroitin is safe and relatively free of side effects when used at the recommended daily dosage, at least for short periods of time. Some people may experience mild stomach upset. So far, few studies have investigated the safety and effectiveness of chondroitin when used for long periods of time.

Pregnancy and Breastfeeding

Pregnant and breastfeeding women should not take chondroitin, since it has not been studied for safety in these groups.

Interactions and Depletions:

If you are currently being treated with any of the following medications, you should talk to your doctor before taking chondroitin:

Anticoagulants (blood-thinners) -- Because chondroitin is similar to heparin, a drug used to thin the blood, it is theoretically possible for chondroitin to enhance the effects of blood-thinners. Chondroitin could also enhance the blood-thinning effects of vitamins and supplements such as fish oil and vitamin E.

Nonsteroidal anti-inflammatory drugs (NSAIDs) -- If you take NSAIDs to relive the pain of OA, taking chondroitin may reduce the dose of NSAIDs you need to take. Since NSAIDs can cause stomach bleeding, reducing the dosage can be helpful. Talk to your doctor, however, before starting to take chondroitin, since it can take several months before any improvements are felt.