A daily dose of 800 mg chondroitin sulphate delays cartilage breakdown in the knee joints of osteoarthritis sufferers. Researchers at the University of Montreal discovered this during a year-long experiment that they conducted.
Chondroitin is a sugar that plays an important role in cartilage. Chondroitin strengthens cartilage and thus makes it better able to withstand shocks. That's why the supplements industry adds it to joint-protection products. Meta-studies have shown that chondroitin has a – mildly – positive effect on the joints of people who suffer from problems with their joints. Supplements manufacturers often combine chondroitin with other active ingredients: a popular combination is chondroitin with glucosamine.
The researchers gave a group of 70 relatively new arthritis sufferers a placebo or two capsules containing 400 mg chondroitin sulphate every day for a year. During the first six months the subjects did not know what they were taking; the second half of the experiment they were told. The supplement used was Condrosan, manufactured by the Spanish Bioibérica. [bioiberica.com] Bioibérica also sponsored the study, and was involved in the writing up of the final report.
During the experiment the researchers examined MRI scans of the subjects' knee joints. The figure on the left below shows that chondroitin supplementation [the solid line] delayed the cartilage breakdown. That effect was statistically significant.
In the figure on the right above you can see the effect on bone tissue damage on the underside of the knee joint. This damage is typically found in people suffering from arthritis, and is caused by the joint's inability to act as a shock absorber. The damage was reduced in the chondroitin group, but the effect was not statistically significant.
Ann Rheum Dis. 2011 Jun;70(6):982-9.