Glucosamine

This is a strong recommendation resting on an absence of benefit rather than on demonstrated harm, and the guideline notes glucosamine's toxicity is low. It hardened from a conditional recommendation against glucosamine in 2012, so a reader may still meet the older advice. The search closed in 2018.

None was designed to detect rare harm, and the participants were people with knee osteoarthritis, not the general population. The chondroitin review's finding of fewer serious events on treatment than on placebo more likely reflects sparse, inconsistently reported data than a real effect.

The 0.9 cm threshold is these authors' own choice rather than an agreed one, and a reader accepting a smaller threshold would read some of these intervals differently. Restricting by trial size excludes most of the older positive literature, so this is not the body of trials other reviews pool.

A placebo response of six in ten leaves very little room for a supplement to show a difference, and every arm could take up to 4,000 mg of paracetamol a day as rescue, narrowing the gaps further. The trial used glucosamine hydrochloride, not the sulfate salt sold in Europe as a medicine.

This is a continuation in the participants who met stricter X-ray criteria, not a fresh randomisation, so it carries the parent trial's high placebo response with it. Two years of dropout leaves less power, not more. The authors call the trends beneficial but not significant, which describes a null.

The result is fragile: its interval reaches to 0.002 mm, its p value is 0.046, and it survives only after adjustment for sex, weight and baseline severity. It is one of several comparisons, so a multiple-testing correction would likely remove it. Whether a tenth of a millimetre is felt is untested.

Risk of bias was the second-largest explanation, cutting the disagreement by a further 32%, so brand and how well a trial was run stay entangled. The shrunken estimate rests on three trials, and even after both factors the trials still disagree substantially. Pain only, nothing on joint structure.

Which preparation a trial used and how rigorously it was designed cannot be separated either: the older, weaker trials are also that manufacturer's. On the standard osteoarthritis questionnaire, pain, function and stiffness reached significance for neither preparation. Its search closed in 2005.

Manufacturer involvement, the salt used and whether allocation was concealed are almost perfectly entangled here, so this cannot say which explains the gap. These are comparisons across trials, not a randomised contrast, so sponsorship is associated with the result, not shown to cause it.

All five datasets shared were independently funded, so the form distinction is tested only inside independent trials, and no dataset from the manufacturer whose product the argument is about was contributed. In the published record, form, sponsorship and concealment cannot be separated.

The five contributed trials still cover 55% of everyone ever randomised in a published placebo-controlled glucosamine trial, so the gap is in which trials are represented, not in people. Because no manufacturer-sponsored dataset arrived, the reanalysis cannot answer those trials on their own data.

Milder knees showed a trend toward benefit with no significance test attached to it, so it is not a result and should not be reported as one. The trial used glucosamine hydrochloride rather than the sulfate salt, which is one of the two ways it differs from the three-year trials reporting a benefit.

This is one manufacturer's label, so its choices are evidence about this product rather than about US labelling rules in general. The document also disagrees with itself: the index title says tablet where the Drug Facts panel and carton say capsule, and three different effective dates appear in it.

Three in ten had knee pain without X-ray-confirmed osteoarthritis, so this is not purely a trial in established disease. Twenty-four weeks is short for a structural endpoint when the trials reporting benefit ran three years. It used a hydrochloride drink, which sulfate proponents reject.

Fifteen people and a single dose cannot rule out rare reactions, and the authors limit their conclusion to the manufacturers' products they tested rather than to glucosamine in general. Nothing here tests a poorly purified product or daily use. Chondroitin comes from cattle or shark cartilage.

This review does not separate trials by manufacturer, by funder, or by how well allocation was concealed, the three things earlier analyses of this literature found decide the answer. Its combination conclusion rests on three trials. It reports direction and significance, no effect sizes.

Whether chondroitin and glucosamine ease pain turns on method, not data. Analyses splitting trials by funder, brand and trial quality find no difference a patient would notice; the review finding a benefit did not split them.

People who choose supplements differ from people who do not in ways no adjustment removes, and a modest reduction turning up in every outcome at once is what that difference usually produces. Preparation and amount went unrecorded. No randomised trial has tested glucosamine against heart outcomes.

The reviewers work for a consultancy that carries out safety assessments for industry clients, and the paper names no client. In the same passage where they set aside the studies reporting a glucose effect, they acknowledge that no long-term trial exists in people with pre-diabetes.

A one-dose glucose challenge and months of resting glucose measure different things, so both results can stand. What neither covers is years of glucosamine in someone who is already glucose intolerant.

The two arms' confidence intervals overlap substantially, so the striking loss-versus-no-loss framing compares each arm against zero rather than against the other. Around 200 people is small for a three-year X-ray endpoint. Both sit in the stratum later analyses found produces larger effects.

Every trial measuring joint structure independently of the manufacturer found nothing, but those ran shorter and used another salt. Nobody has repeated the three-year sulfate trial without its manufacturer.

Three people identified after the study began is a hypothesis rather than a finding, and the authors hedge their own conclusion accordingly. It was one dose alongside a 75 g glucose load, with no placebo group described. Larger reviews of fasting glucose over months and years find no such effect.