Do not count on glucosamine or chondroitin to treat knee osteoarthritis
After 24 weeks, six out of ten people taking a placebo reported less knee pain. Glucosamine or chondroitin improved on that by only around four or five percentage points, differences small enough to be explained by chance. Spending RMB 700–1,800 a year did not establish a benefit beyond the substantial improvement also seen with a placebo.
What it takes
About RMB 2–5 a day, or 700–1,800 a year.
What you may gain
GAIT enrolled 1,583 people with knee osteoarthritis for 24 weeks. Pain improved in 60.1% of the placebo group. Glucosamine increased that response rate by 3.9 percentage points (P=0.30), chondroitin by 5.3 points (P=0.17), and the combination by 6.5 points (P=0.09). None established a statistically significant difference. Celecoxib, the active medicine included for comparison, improved the rate by 10.0 percentage points (P=0.008). The supplements sound convincing because “supplying the raw material for cartilage” seems to address the problem directly, while substantial improvement even with a placebo makes personal experience persuasive.
Context & considerations
A qualification: among participants whose pain was more severe at the outset, response rates were 79.2% with the combination and 54.3% with placebo (P=0.002). The authors treated this exploratory subgroup finding as a lead for further research rather than a firm conclusion. Weight loss and muscle strengthening have supporting evidence for knee osteoarthritis; see chapter 2.
Research & references
Clegg DO et al. (2006). Glucosamine, chondroitin sulfate, and the two in combination for painful knee osteoarthritis. NEJM. https://doi.org/10.1056/NEJMoa052771.