How Chondroitin Works

Chondroitin sulfate is easily taken up from the intestine into the blood stream (Conte et al 1995; Ronca et al 1998) in animals and in humans. Ronca et al (1998) were able to show rapid absorption of chondroitin sulfate that was administered orally. About 10% of the chondroitin sulfate found its way into the blood stream. 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. Ronca et al (1998) examined the joint fluid of patients with knee osteoarthritis after a 10-day course of chondroitin sulfate at 800 mg/day. They found that chondroitin sulfate reduced inflammation better than indomethacin and ibuprofen (both of which are NSAIDs). The presence of substances associated with cartilage breakdown also was reduced, while the lubricant properties of the joint fluid were enhanced.

How Chondroitin Sulfate Compares to NSAIDs

In a multicenter, randomized trial, Morreale et al (1996) found that diclofenac (an 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, Leeb et al (1996) 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% throughout the three months of chondroitin sulfate treatment. Similar results were found in a randomized trial (Mazieres et al 1992).

Side Effects of Chondroitin

Side effects may include nausea if more than 10,000 mg are taken in one day. Without apparent exception, trials and reviews of chondroitin sulfate for osteoarthritis conclude that it is well tolerated and safe (e.g., McAlindon et al 1998). The most frequent side effects mentioned with its use are mild stomach upsets and excess gas.

Appropriate Dose of Chondroitin Sulfate

The best dose of chondroitin sulfate is not known. Most research studies have used doses of 800 to 1,200 mg per day, usually in one or two doses. Because supplement manufacture is more loosely regulated than drug manufacture and producers voluntarily follow good manufacturing practices, purchase chondroitin from reputable suppliers.