How we rate
“Strong” = several concordant meta-analyses or systematic reviews. “Moderate” = one synthesis, or several controlled trials. “Limited” = early trials only. The rating is about the quality of the studies, not about how useful the supplement is.
Glucosamine
A natural cartilage component, among the most studied joint supplements — and the most debated.
Benefits
- Relieves knee pain and stiffness at 1,500 mg per day of sulfate — as well as ibuprofen over 4 weeks, with significantly fewer digestive effects
- Slows the narrowing of the knee joint over 3 years, where the placebo continues to degrade
- Eight years later, 6.3% of treated patients had received a knee replacement, compared to 14.5% under placebo
- Combined with chondroitin, as effective as celecoxib over 6 months in 606 patients
Precautions
Often extracted from shellfish carapaces: to be avoided in case of allergy. Monitoring recommended in case of diabetes or anticoagulant treatment. Also worth knowing, and it is important: the results are clearly divided. The largest independent trials — including GAIT, 1,583 patients — find no better than placebo on pain. Form matters: glucosamine sulfate shows an effect, hydrochloride does not, and trials funded by the manufacturer of the most studied form are the most favorable. Allow at least 8 weeks before judging, and stop if nothing changes.
Recommended dosage
1,500 mg per day of glucosamine sulfate, in a single dose or in three 500 mg doses.
How to take it
- Dose: 1,500 mg per day, in a single dose or in three 500 mg doses depending on the trials.
- Sulfate, not hydrochloride: the review of 15 trials finds an effect with glucosamine sulfate, not with hydrochloride.
- Preparation matters: studies on a specific preparation, called "Rotta", are positive, others are not. Researchers also point to the role of industry in these discrepancies.
- How long: some trials see symptoms improve from 4 weeks, others do no better than placebo after 12 weeks or 6 months. The effect on the joint is measured over 3 years.
- On the long term: in patients treated for 1 to 3 years, knee replacement surgery was twice as infrequent over 8 years of follow-up (6.3% vs 14.5%).
What the studies say
A network meta-analysis examined the effects of glucosamine, chondroitin, or their combination on joint pain and radiological progression of hip or knee osteoarthritis. The results showed that, compared to placebo, these supplements did not reduce joint pain in a clinically significant manner. Similarly, no significant impact was observed on joint space narrowing. The authors conclude that these preparations should not be reimbursed and that new prescriptions should be discouraged.
Wandel S, Jüni P, Tendal B, Nüesch E, Villiger PM, Welton NJ, Reichenbach S, Trelle S. — BMJ (Clinical research ed.) (2010) — View the source study
For information only: not a substitute for medical advice. Dietary supplements are not a replacement for a varied, balanced diet. Learn more