Dr. David Ramey is an equine veterinarian and a tireless advocate for evidence-based veterinary medicine. He is the author of numerous publications, including Complementary and Alternative Veterinary Medicine Considered (2004), Consumer's Guide to Alternative Therapies in the Horse, and the equine series of Concise Guides. The following is crossposted from the ALTVETSKEPT-L e-mail list, with permission from Dr. Ramey.
I keep promising myself to write a summary of why I
think glucosamine is worthless, mostly because I find the
claims so inflated and aggravating. Here goes (with
apologies to those who don't find the subject of interest).
1. At least in North America, glucosamine is an
over-the-counter dietary supplement and preparations made by different manufacturers have been shown to vary (including one study on horse products by your truly). There may not be much glucosamine in your glucosamine.
2. The last four consecutive well-conducted clinical
trials have all shown no effect. This is in contradistinction to the first 20-some, which suggested an anti-inflammatory and, in a few, a chondroprotective effect. Curiously, the last four trials were independently funded, whereas the first 20-some were funded by the glucosamine industry.
3. Recent in vitro studies show that glucosamine does
not stimulate synthesis of chondroitin sulfate (Mroz and
Silbert, Biochem J 2003; 376: 511 - 515). In fact, in
higher concentrations, it inhibits CS synthesis.
4. At the doses given, even if completely absorbed,
equally distributed and not metabolized, it is extremely
unlikely that relevant concentrations could reach the joint
(details of calculations in the Mroz paper).
5. It's questionable whether glucosamine even gets into
the systemic circulation following oral ingestion. Most of
it gets taken to the liver where it gets metabolized or
incorporated into glycoproteins. This is confirmed in
humans, dogs and rats (references available).
6.Glucosamine is not ordinarily available in the
circulation as a source of components for synthesis of
cartilage matrix. Cartilage uses glucose for this purpose.
Glucosamine is NOT essential for the biosynthesis of
David Ramey, DVM