MSM (methylsulfonylmethane)

MSM is an organosulfur compound — a DMSO metabolite — sold on the idea that it supplies sulfur for connective tissue and, better supported, that it blunts NF-κB-driven inflammatory signalling. The mechanistic case rests almost entirely on cell and animal work; there is no direct evidence that oral MSM changes human cartilage biology. What it has is a short stack of small, consistent, honest trials.

The three trials

Kim 2006 (n=50, 6 g/day, 12 weeks): WOMAC pain fell 14.6 points on MSM versus 7.2 on placebo (p=0.041), with improved physical function. Stiffness and the aggregate symptom score did not separate — and the placebo group achieved half the MSM improvement.

Debbi 2011 (n=49, 3.375 g/day, 12 weeks): significant but small gains in WOMAC physical function and total score. The authors explicitly questioned whether their own effect size was clinically meaningful — a candor worth rewarding with the caution it asks for.

Usha 2004 (n=118, 12 weeks): MSM 1.5 g/day reduced pain and swelling versus placebo, and MSM plus glucosamine outperformed either alone (pain index falling from 1.7 to 0.36 versus roughly 0.9–1.0 on monotherapy). One Indian centre, a nonstandard pain index, and about 25% dropout — and the additive combination finding has never been replicated.

What's missing

No trial exceeds 12 weeks or ~120 participants. No imaging or structural outcomes exist anywhere in the MSM literature. No frankly null RCT has been published either — but with an evidence base this thin, the absence of contradiction mostly reflects the absence of trials, and a run of small positive studies is exactly the pattern publication bias produces. A properly powered trial of several hundred patients over 6–12 months would settle it; none appears to be registered.

Dose & practical notes

Trials used 1.5–6 g/day, usually divided; the strongest single-agent result used 3 g twice daily. Where benefits appeared, they emerged by 8–12 weeks. Optimal dose is unresolved — the trialed range spans fourfold. MSM is often bundled with glucosamine in retail products; whether that adds anything rests on the single 2004 factorial trial.

Safety

This is the strongest part of the file. MSM was well tolerated at up to 6 g/day in trials, with adverse events (mild GI upset, headache) comparable to placebo, and it holds US GRAS status. No established drug interactions, though data in pregnancy and severe renal or hepatic disease are absent.

What I take from it

MSM sits in an odd spot: cheap, safe, and consistently a little better than placebo in every trial run — but every trial was small, short, and symptom-scored, and the researchers closest to the data keep flagging that "statistically significant" and "worth taking" are different claims. A reasonable low-stakes experiment for symptoms; not a cartilage therapy on any current evidence.