Mixed results on glucosamine and chondroitin

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Glucosamine and chondroitin are popularly used as treatments for osteoarthritis and by extension all manner of cartiliginous-type joint injuries. Unfortunately, the effectiveness data is pretty thin. The results of the Glucosamine/chondroitin Arthritis Intervention Trial are now out and they don't show that much of a useful result. Basically, neither glucosamine nor chondroitin alone outperforms placebo and the glucosamine/chondroitin combination outperforms placebo only for patients with moderate-to-severe pain.

It's not clear what to make of this, for the following reasons:

  • The response rate for placebo was incredibly high: 60% of patients showed response. This makes it hard for any treatment to look good.
  • celecoxib (Celebrex) was significantly better than placebo at the 95% confidence level for the whole group but not for either the mild or moderate-to-severe pain subgroups (this is a study power issue issue). So, clearly we need a larger study group. (n=1583 for this study).
  • Chondroitin does show a significant effect on joint swelling (one of the secondary outcomes).
  • The moderate-to-severe pain combined glucosamine/chondroitin group may just have been underpowered.
  • The study used glucosamine hydrochloride rather than glucosamine sulfate (see here for one comment on this). It's not clear if it makes a difference here, but the cation can make a difference (don't mistake NaCl for NaCN!).

The bottom line is that it's hard to draw any firm conclusions here.

Another thing to consider is that many people (especially athletes) who take glucosamine/chondroitin have an injury rather than osteoarthritis. As far as I know there's no data (other than anecdotal) that glucosamine/chondroitin works on this kind of injury (which is even less susceptible to study because it tends to heal on its own).

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The New York Times had an article which presented the results as much more definitively negative.

Have you noticed this amazing tendency by the mainstream press to not understand the information in scientific papers they report on?

The recent "Oh, low fat has no effect on health!" news reports which clearly were based on not reading the study are another example.

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