The pair narrowed the joint 0.10 mm less, and pain did not follow
605 Australians took glucosamine, chondroitin, both or placebo for two years. Only the combined arm narrowed less than placebo. Knee pain fell equally in all four groups.
What the study found
Two years on both bought a tenth of a millimetre and no less pain
Six hundred and five Australians took glucosamine, chondroitin, both, or placebo once daily for two years. Only the combined arm narrowed less than placebo, by 0.10 mm; neither agent alone touched the joint. Knee pain fell in all four groups, placebo included, with no difference.
The caveat · Barely significant, among many tests
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.