Originally Posted by
moytoy
Do you have a link to the studies you mention? After WOO posed the question in the OP I have started my own test on gelatin (knox) and would be interested in reading the studies.
As a rheumatologist who used to see lots of patients with DJD (I stopped patient care ~ 10 yrs ago) this question was pretty popular, so I tried to do some research into the studies around this. Early on there were a number of relatively small clinical trials showing modest but statistically significant beneficial effects from oral glucosamine, and various injections of related compounds into the joints. Many of these studies were supported by the companies selling these suplements, so you have to be a little cautious in relying on them - there's a well known phenomenon where studies that sjhow a positive effect are much more likely to be poublished than studies that show a negative effect. Statistical significance is defined (usually) as no more than a 5% chance of the results occring due to chance. to oversimplify a bit, this means that if 20 studies of an ineffective therapy are done, 1 of the studies will probably give a positive "statistically significant" result (actually the statistics are different, but i'm over simplfying to make a point).
Here's a recent metaanalysis of the clincial trials addressing the topic:
Wandel S, Jüni P, Tendal B, et al.
Effects of glucosamine, chondroitin,
or placebo in patients with osteoarthritis of hip or knee: network
meta-analysis. BMJ. 2010;341:c4675.
Question
Do glucosamine or chondroitin, alone or in combination, reduce
joint pain in osteoarthritis of the hip or knee?
Review scope
Included studies compared glucosamine sulfate, glucosamine
hydrochloride, chondroitin sulfate, or a combination of 2 of the
drugs with each other or placebo and included
≥ 100 patients
with osteoarthritis of the hip or knee in each treatment group.
Treatment groups with subtherapeutic drug doses (glucosamine
<
1500 mg/d, chondroitin < 800 mg/d) were excluded. Primary
outcome was pain intensity.
Review methods
MEDLINE, EMBASE/Excerpta Medica, CINAHL, and
Cochrane Controlled Trials Register (all to Jun 2010); Science
Citation Index (1981 to 2008); conference proceedings; textbooks;
and reference lists were searched for randomized controlled trials
(RCTs). Experts were contacted. 10 RCTs (
n = 3803) met the
selection criteria (median age 62 y, median 68% women); 8 involved
the knee joint, 1 the hip joint, and 1 both joints. Duration
of follow-up ranged from 1 month to 36 months. Data from direct
and indirect treatment comparisons were combined using Bayesian
network meta-analysis. Pain was evaluated using different scales,
combined using effect sizes, and converted to a 10-cm visual
analogue scale (VAS). A minimal clinically important difference
between treatments of 0.9 cm was prespecified to facilitate interpretation.
Pooled effect sizes and corresponding 95% credible
intervals (CrIs) were estimated from the median and 2.5th and
97.5th centiles of the posterior distribution.
Main results
Meta-analysis showed that glucosamine reduced joint pain intensity
more than placebo; the difference was not clinically important,
with an upper 95% CrI limit
< −0.9 cm (Table). Chondroitin alone
or combined with glucosamine did not reduce joint pain
intensity more than placebo (Table).
Conclusion
Glucosamine and chondroitin, alone or in combination, do not
clinically improve joint pain in patients with osteoarthritis of the
knee or hip.
Source of funding: Swiss National Science Foundation.
Drug treatment vs placebo for joint pain in osteoarthritis of the
knee or hip*
Drug Number of direct Difference in pain intensity (95%
comparisons (n) CrI) on 10-cm visual analogue scale†
Glucosamine 7 (1922)
−0.4 cm (−0.7 to −0.1)
−0.3 cm (−0.7 to 0.0)
Glucosamine + chondroitin 1 (630)
−0.5 cm (−0.9 to 0.0)
*CrI = credible interval.
†Based on data from multiple time points and calculated using network meta-analysis and
Bayesian random-effects models with minimally informative priors. Negative values indicate a
benefit for drug treatment.
I'll put more info into anohter post, as this one's already pretty long...
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Yeah, I loved it...the husband was..."you are weird" 
