Chondroitin sulfate is easily taken up from the intestine into the bloodstream in animals and in humans. In one study, researchers were able to show rapid absorption of chondroitin sulfate that was administered orally. About 10 percent of the chondroitin sulfate found its way into the bloodstream. Intact chondroitin sulfate and various breakdown products were selectively taken up by cartilage.
In normal cartilage, chondroitin sulfate chains form a dense microscopic mesh together with collagen fibers. This three-dimensional meshwork keeps water embedded and so enables cartilage to absorb mechanical stress. In one study, researchers examined the joint fluid of patients with knee osteoarthritis after a 10-day course of chondroitin sulfate at 800 mg per day. They found that chondroitin sulfate reduced inflammation better than indomethacin and ibuprofen (both of which are nonsteroidal anti-inflammatory drugs, or NSAIDs). The presence of substances associated with cartilage breakdown also was reduced, while the lubricant properties of the joint fluid were enhanced.
In one large study, researchers found that diclofenac (a nonsteroidal anti-inflammatory drug, or NSAID) given three times per day in 50 mg doses brought faster relief than chondroitin sulfate administered three times per day at 400 mg each. However, arthritis symptoms promptly reappeared when diclofenac treatment ended. Although participants in the chondroitin sulfate group took longer to get relief, it lasted for up to three months after the end of treatment.
In an open multicenter trial, researchers treated patients with osteoarthritis of the hip, knee, and/or finger joints with NSAID and chondroitin sulfate for three months. The NSAID doses, which were necessary for pain control at the beginning of the study, could be reduced by 72 percent throughout the three months of chondroitin sulfate treatment. Similar results were found in a randomized trial.
