Osteoarthritis and Chondroitin

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. Chondroitin is not an essential nutrient. Animal cartilage is the only dietary source of chondroitin. (When it's on your plate, animal cartilage is called gristle.) Unless you enjoy chewing gristle, you'd do best to obtain chondroitin in pill form from a health food store or pharmacy.

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.

There is some evidence that chondroitin might go beyond treating symptoms and actually protect joints from damage. Current medical treatments for osteoarthritis, such as nonsteroidal anti-inflammatory drugs (NSAIDs), treat the symptoms but don't actually slow the disease's progression, and they may actually make it get worse faster.^1-5 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 exciting possibility is real.

Read more details about Chondroitin.

Numerous double-blind studies have found evidence that chondroitin can relieve the symptoms of osteoarthritis and possibly also slow the progression of the disease.^9-16 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.⁴³ On balance, the evidence for chondroitin’s effectiveness for osteoarthritis is inconsistent and incomplete.^45,46

Chondroitin has also been proposed as a treatment for other conditions, such as atherosclerosis, interstitial cystitis, and high cholesterol, but as yet the evidence that the supplement might help is far too weak to rely upon at all.^17-18,40

One small double-blind study evaluated chondroitin for reducing muscle soreness caused by intense exercise, but failed to find benefit.⁴¹

What Is the Scientific Evidence for Chondroitin?

For years, experts stated that oral chondroitin couldn't 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% of chondroitin is absorbed intact.¹⁹

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 85 people with osteoarthritis of the knee and followed them for 6 months.⁹ Participants received either 400 mg of chondroitin sulfate twice daily or placebo. At the end of the trial, doctors rated the improvement as good or very good in 69% of those taking chondroitin sulfate, but in only 32% of those taking placebo.

Another way of comparing the results is to look at 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 at all in the placebo group. Additionally, there were improvements in other measures of osteoarthritis, such as pain level, with benefits seen as early as 1 month. This suggests that chondroitin was able to stop the arthritis from gradually getting worse. (See also Slowing the Progression of Osteoarthritis.)

Good results were seen in a 12-month, double-blind trial that compared chondroitin against placebo in 104 people, a 12-month trial of 42 people,11 and a 12-month study of 120 people.³⁷

In two of these studies, chondroitin was taken for two separate 3-month periods separated by 3 months of no treatment;10,37 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.^12,13,15

Another double-blind study compared chondroitin to the anti-inflammatory drug diclofenac and found equivalent benefits.¹⁶

Additional studies combined glucosamine with chondroitin. A 6-month, double-blind, placebo-controlled study of 93 people with knee arthritis found that a combination of glucosamine and chondroitin (along with manganese) was more effective than placebo.¹⁴ Another double-blind, placebo-controlled study evaluated chondroitin/glucosamine for temporomandibular joint disease (TMJ) but found equivocal results.²⁰

However, a very large (1,583 participants) and well-designed study failed to find either chondroitin or glucosamine plus chondroitin more effective than placebo.42 When this study is pooled together with the two other best designed trials, no overall benefit is seen.⁴³ Yet another study also failed to find benefit with glucosamine plus chondroitin.⁴⁴ And finally, in a systematic review including 10 randomized trials involving 3,803 patients with osteoarthritis of hip or knee, researchers found that chondroitin alone or with glucosamine did not improve pain.⁴⁶

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. Some evidence hints that chondroitin can do this, but it is too early to consider the matter settled.³⁸

One study examined the progression of osteoarthritis in 119 people for 3 years.22 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% of the chondroitin group developed severely damaged joints during the 3 years of the study, compared with almost 30% of the placebo group. This suggests that chondroitin was slowing the progression of osteoarthritis.

Protective effects were also seen in three 1-year studies enrolling a total of more than 200 people.^10,11,37

Animal studies provide some additional evidence for a joint-protecting benefit.²³ However, as with studies of chondroitin for treating osteoarthritis, too high a proportion of the research record involving prevention of osteoarthritis has involved industry-funded research.

How Does Chondroitin Work for Osteoarthritis?

Scientists are unsure how chondroitin sulfate works (if indeed it does).

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.^23,24 Another theory holds that chondroitin increases the amount of hyaluronic acid in the joints.²⁵ Hyaluronic acid is a protective fluid that keeps the joints lubricated. Finally, chondroitin may have a mild anti-inflammatory effect.²⁴

Safety Issues

Chondroitin generally does not cause much in the way of side effects, besides occasional mild digestive distress. However, there is one case report of an exacerbation of asthma caused by use of a glucosamine-chondroitin product. ¹ 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. ² 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.

Interactions You Should Know About

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

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2. Abdel Fattah W, Hammad T. Chondroitin sulfate and glucosamine: A review of their safety profile. JANA. 2001;3:16-23.

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21. Cohen M, Wolfe R, Mai T, et al. A randomized, double blind, placebo controlled trial of a topical cream containing glucosamine sulfate, chondroitin sulfate, and camphor for osteoarthritis of the knee. J Rheumatol. 2003;30:523-528.

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23. Uebelhart D, Thonar EJ, Zhang J, et al. Protective effect of exogenous chondroitin 4, 6-sulfate in the acute degradation of articular cartilage in the rabbit. Osteoarthritis Cartilage. 1998;6(suppl A):6-13.

24. Ronca F, Palmieri L, Panicucci P, et al. Anti-inflammatory activity of chondroitin sulfate. Osteoarthritis Cartilage. 1998;6(suppl A):14-21.

25. Hungerford DS. Treating osteoarthritis with chondroprotective agents. Orthopedic Special Edition. 1998;4:39-42.

26. Tallia AF, Cardone DA. Asthma exacerbation associated with glucosamine-chondroitin supplement. J Am Board Fam Pract. 2002;15:481-484.

27. Abdel Fattah W, Hammad T. Chondroitin sulfate and glucosamine: A review of their safety profile. JANA. 2001;3:16-23.

28. Uebelhart D, Thonar EJ, Delmas PD, et al. Effects of oral chondroitin sulfate on the progression of knee osteoarthritis: a pilot study. Osteoarthritis Cartilage. 1998;6(suppl A):39-46.

29. Verbruggen G, Goemaere S, Veys EM. Chondroitin sulfate: S/DMOAD (structure/disease modifying anti-osteoarthritis drug) in the treatment of finger joint OA. Osteoarthritis Cartilage. 1998;6(suppl A):37-38.

30. Conrozier T. Anti-arthrosis treatments: efficacy and tolerance of chondroitin sulfates (CS 4&6) [translated from French]. Presse Med. 1998;27:1862-1865.

31. Uebelhart D, Thonar EJ, Zhang J, et al. Protective effect of exogenous chondroitin 4, 6-sulfate in the acute degradation of articular cartilage in the rabbit. Osteoarthritis Cartilage. 1998;6(suppl A):6-13.

32. Uebelhart D, Thonar EJ, Zhang J, et al. Protective effect of exogenous chondroitin 4, 6-sulfate in the acute degradation of articular cartilage in the rabbit. Osteoarthritis Cartilage. 1998;6(suppl A):6-13.

33. Ronca F, Palmieri L, Panicucci P, et al. Anti-inflammatory activity of chondroitin sulfate. Osteoarthritis Cartilage. 1998;6(suppl A):14-21.

34. Hungerford DS. Treating osteoarthritis with chondroprotective agents. Orthopedic Special Edition. 1998;4:39-42.

35. Ronca F, Palmieri L, Panicucci P, et al. Anti-inflammatory activity of chondroitin sulfate. Osteoarthritis Cartilage. 1998;6(suppl A):14-21.

36. Abdel Fattah W, Hammad T. Chondroitin sulfate and glucosamine: a review of their safety profile. JANA. 2001;3:16-23.

37. Uebelhart D, Malaise M, Marcolongo R, et al. Intermittent treatment of knee osteoarthritis with oral chondroitin sulfate: a one-year, randomized, double-blind, multicenter study versus placebo. Osteoarthritis Cartilage. 2004;12:269-276.

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46. Wandel S, Jüni P, Tendal B, et al. Effects of glucosamine, chondroitin, or placebo in patients with osteoarthritis of hip or knee: network meta-analysis. BMJ. 2010;341:c4675.