Don't count on glucosamine/chondroitin to treat knee osteoarthritis

High value
Evidence A
Saves money
Disputed
Free
Takes minutes
No willpower

In plain words

People with knee osteoarthritis who took a fake pill for 24 weeks also had about 60% say it hurt less. People taking glucosamine or chondroitin did only 4 to 5 percentage points better than that, a gap so small it may be chance. For 700 to 1800 CNY a year, what you mostly buy is that 60% effect of the mind.

Cost: About 2 to 5 CNY a day, 700 to 1800 CNY a year.
What you get: The GAIT trial enrolled 1,583 people with knee osteoarthritis and ran for 24 weeks. Even among those given a placebo (fake pill), 60.1% said their pain eased. Glucosamine beat that by only 3.9 percentage points (P=0.30). Chondroitin by 5.3 points (P=0.17). The two together by 6.5 points (P=0.09). All these gaps are too small to rule out chance. In the same trial, celecoxib, a real drug used as a comparison, beat it by 10.0 points (P=0.008). It looks like a good deal because “building blocks for cartilage” sounds like it fits the problem exactly, and a fake pill alone gets about 60% of people saying it works
Notes: Dispute: in the same trial, among those who had severe pain at the start, the response rate with the two taken together was 79.2% versus 54.3% in the comparison group (P=0.002). But the authors say this was dug out of the data after the fact, so it can only be a lead, not a conclusion. What actually has evidence for knee arthritis is losing weight and building muscle; see §2
Evidence grade: A : Specific numbers from meta-analyses, large cohorts or randomized trials; for law and policy, the statute or official text.
Sources: Clegg DO et al. (2006). Glucosamine, chondroitin sulfate, and the two in combination for painful knee osteoarthritis. NEJM. https://doi.org/10.1056/NEJMoa052771

Translated from the Chinese original. Original book, section 6, tip 5. Content may be out of date and rules differ by place. When you actually deal with an agency, a doctor or a court, follow what local officials, doctors and lawyers tell you. Disclaimer