Chondroitin as a therapeutic supplement

• DEFINITION: Natural substance of the human body used as a supplement to treat specific health conditions.
• PRINCIPAL PROPOSED USE: Osteoarthritis
• OTHER PROPOSED USES: Atherosclerosis, eye health, high cholesterol, sports and fitness support: enhancing recovery

Overview

Chondroitin sulfate is a naturally occurring substance in the body. It is a major constituent of cartilage, the tough, elastic connective tissue found in the joints.

Based on the evidence of preliminary double-blind studies, chondroitin is widely used as a treatment for osteoarthritis, the typical arthritis that many people suffer as they get older. However, the supporting evidence for this use is weak.

There is some evidence that chondroitin might go beyond treating symptoms and actually protect joints from damage. Modern medical treatments for osteoarthritis, such as nonsteroidal anti-inflammatory drugs (NSAIDs), treat the symptoms but do not actually slow the disease’s progression, and they may actually make it get worse faster. Chondroitin (along with glucosamine) may take the treatment of osteoarthritis to a new level. However, more research needs to be performed to prove definitively that this possibility is real.

Chondroitin is used in solutions during cataract and other eye surgeries to protect ocular tissues and is an ingredient in prescription eye drops for dry eye relief.

Requirements and Sources

Chondroitin is not an essential nutrient. Animal cartilage is the only dietary source of chondroitin. (Animal cartilage in food is called gristle or gelatin.) Chondroitin is available in pill form and can be purchased from a health-food store or pharmacy.

Therapeutic Dosages

The usual dosage of chondroitin is 400 milligrams (mg) taken three times daily, indefinitely. Several studies used an on-and-off schedule of chondroitin—taking it for three months, going off of it for three months, and then taking it again. Other studies involved taking chondroitin daily. Regardless of how it is taken, the results are thought to take weeks to develop.

In commercial products, chondroitin is often combined with glucosamine. Some information from animal studies suggests that this combination may be superior to treatment by either substance alone.

There are large differences between chondroitin products based on their chemical structure. This can be expected to lead to significant differences in absorption and, hence, effectiveness. Most likely, chondroitin products with physically smaller molecules (fewer than 16,900 daltons) are better absorbed. In addition, a review conducted by a respected testing organization found that some products marketed to provide chondroitin actually contained far less chondroitin than stated on the label, or even no chondroitin. It may be advisable to use the exact products that have been tested in double-blind trials.

Therapeutic Uses

Numerous double-blind studies have found evidence that chondroitin can relieve the symptoms of osteoarthritis and possibly also slow the progression of the disease. However, most of these studies suffer from serious problems in design, statistical analysis, and reporting. When pooled together, the results of the three best studies failed to demonstrate benefit. The evidence for chondroitin’s effectiveness for osteoarthritis is inconsistent and incomplete.

Chondroitin has also been proposed as a treatment for other conditions, such as atherosclerosis, interstitial cystitis, and high cholesterol, but evidence that the supplement might help is far too weak to rely upon. One small double-blind study evaluated chondroitin for reducing muscle soreness caused by intense exercise but failed to find benefits.

Scientific Evidence

For years, experts stated that oral chondroitin could not possibly work because its molecules are so big that it seemed doubtful that they could be absorbed through the digestive tract. However, in 1995, researchers laid this objection to rest when they found evidence that up to 15 percent of chondroitin is absorbed intact.

Reducing symptoms of osteoarthritis. Many, but not all, double-blind, placebo-controlled studies indicate that chondroitin can relieve symptoms of osteoarthritis. For example, one study enrolled eighty-five people with osteoarthritis of the knee and followed them for six months. Participants received either 400 mg of chondroitin sulfate twice daily or a placebo. At the end of the trial, doctors rated the improvement as good or very good in 69 percent of those taking chondroitin sulfate but in only 32 percent of those taking a placebo.

Another way of comparing the results is to look at the maximum walking speed among participants. Whereas individuals in the chondroitin group were able to improve their walking speed gradually over the course of the trial, walking speed did not improve in the placebo group. Additionally, there were improvements in other measures of osteoarthritis, such as pain level, with benefits seen as early as one month. This suggests that chondroitin was able to stop the arthritis from gradually getting worse.

Good results were seen in a twelve-month double-blind trial that compared chondroitin against placebo in 104 people, a twelve-month trial of 42 people, and a twelve-month study of 120 people. In two of these studies, chondroitin was taken for two separate three-month periods separated by three months of no treatment; in the others, it was taken continuously. No comparison of these two ways of using chondroitin has been published. Benefits were also seen in two other double-blind, placebo-controlled trials involving a total of more than 350 individuals. Another double-blind study compared chondroitin to the anti-inflammatory drug diclofenac and found equivalent benefits.

Additional studies combined glucosamine with chondroitin. A six-month double-blind, placebo-controlled study of ninety-three people with knee arthritis found that a combination of glucosamine and chondroitin (along with manganese) was more effective than a placebo. Another double-blind, placebo-controlled study evaluated chondroitin/glucosamine for temporomandibular joint (TMJ) disease but had equivocal results.

However, a very large (1,583 participants) and well-designed study failed to find either chondroitin or glucosamine plus chondroitin more effective than a placebo. When this study is pooled together with the two other best-designed trials, no overall benefit is seen. Yet another study also failed to find benefits with glucosamine plus chondroitin. Finally, in a systematic review including ten randomized trials involving 3,803 patients with osteoarthritis of the hip or knee, researchers found that chondroitin alone or with glucosamine did not improve pain. It has been suggested that chondroitin, like glucosamine, may primarily appear effective in studies funded by manufacturers of chondroitin products.

Slowing the progression of osteoarthritis. Osteoarthritis tends to worsen with time. As mentioned earlier, no conventional treatment for osteoarthritis protects joints from progressive damage. Evidence hints that pharmacologic-grade supplements have the potential to make significant differences in symptoms if they are standardized and taken as advised.

One study examined the progression of osteoarthritis in 119 people for three years. In this double-blind, placebo-controlled trial, those who took 1,200 mg of chondroitin daily showed lower rates of severe joint damage. Only 8.8 percent of the chondroitin group developed severely damaged joints during the three years of the study, compared with almost 30 percent of the placebo group. This suggests that chondroitin was slowing the progression of osteoarthritis. Protective effects were also seen in three one-year studies enrolling a total of more than 200 people.

How chondroitin works for osteoarthritis. Scientists are unsure how chondroitin sulfate works. At its most basic level, chondroitin may help cartilage by providing it with the building blocks it needs to repair itself. Chondroitin is also believed to block enzymes that break down cartilage in the joints. Another theory holds that chondroitin increases the amount of hyaluronic acid in the joints. Hyaluronic acid is a protective fluid that keeps the joints lubricated. Finally, chondroitin may have a mild anti-inflammatory effect.

Safety Issues

Chondroitin generally does not cause many side effects, besides occasional mild digestive distress. However, there is one case report of an exacerbation of asthma caused by the use of a glucosamine-chondroitin product. In addition, there are theoretical concerns that chondroitin might have a mild blood-thinning effect based on its chemical similarity to the anticoagulant drug heparin. Reassuringly, there are no case reports of any problems relating to this, and studies suggest that chondroitin has, at most, a mild anticoagulant effect. Nonetheless, prudence suggests that, based on these findings, chondroitin should not be combined with blood-thinning drugs, such as warfarin (Coumadin), heparin, and aspirin, except under physician supervision. In addition, individuals with bleeding problems, such as hemophilia, or who are temporarily at risk for bleeding (for example, undergoing surgery or labor and delivery) should avoid chondroitin.

Important Interactions

Persons using drugs that impair blood coagulation, such as warfarin (Coumadin), heparin, aspirin, clopidogrel (Plavix), ticlopidine (Ticlid), or pentoxifylline (Trental), should not use chondroitin except under physician supervision.

Bibliography

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