Millions of Britons spend over £50 million a year on glucosamine supplements for joint pain, but a BBC investigation has revealed significant discrepancies in the amount of active ingredient in some products. Tests commissioned by BBC Two's 'Trust Me, I'm a Doctor' found that two out of nine popular brands contained less than 75% of the glucosamine claimed on the label.
Dr Cristina Legido-Quigley and her team at King's College London analysed the supplements. While six brands contained 90% or more of the advertised amount, two fell short, meaning a pill claiming 1000mg could contain under 750mg. Price was no indicator of quality: a brand costing nearly £300 a year had similar levels to one costing just £9 annually.
The programme also conducted an eight-week trial with 74 volunteers suffering knee pain. One group did daily exercises to strengthen muscles around the knee, while the other took a daily pill—later revealed to be a placebo. In the exercise group, 80% saw symptoms improve by over a third. In the placebo group, 55% reported similar improvement, highlighting the powerful placebo effect.
Previous studies on glucosamine have been inconclusive. A 2010 meta-analysis in the British Medical Journal found no conclusive benefit but noted that patients who believe it helps and experience no harm may continue. Other reviews suggest possible benefits. The BBC trial suggests that while glucosamine may be no better than placebo, the placebo effect itself can be significant, and exercise remains a proven intervention.
