Glucosamine No Help for Osteoarthritic Knee Pain

The popular dietary supplement glucosamine shows no evidence of structural benefits among patients with chronic knee pain typical of osteoarthritis (OA), according to a new study.

Researchers at the University of Utah (Salt Lake City, USA), the University of Arizona (Tucson, USA), and other institutions conducted a randomized, double-blind placebo-controlled trial that enrolled 201 participants with mild to moderate pain in one or both knees. Participants had 24 weeks of treatment with 1,500 mg glucosamine hydrochloride in beverage form or a placebo beverage. The primary outcome was decreased worsening of cartilage damage in all knees identified by magnetic resonance imaging (MRI). Secondary outcomes included change in bone marrow lesions (BMLs) in all knees and excretion of urinary C-terminal cross-linking telopeptide of type II collagen (CTX-II).

The results showed that throughout the trial there was deterioration in cartilage as seen on MRI in only 1.41% of knee subregions—less than the researchers expected. The secondary outcome, urinary excretion CTX-II, a marker of cartilage deterioration, showed no statistically significant difference between groups, although a slight improvement was seen among controls. There also was no difference for patient-reported pain or function on the Western Ontario and McMaster Universities (WOMAC) scales, or in the rates of adverse events. The study was published on March 10, 2014, in Arthritis & Rheumatology.

“Although tempting to say that no advantage to glucosamine was shown and even some evidence that it was worse than placebo, we need to temper our interpretation because of the low rate of progression, as this means the study did not have adequate power to detect even a relatively large difference between treatment and placebo,” said Allen Sawitzke, MD, of the University of Utah. “It suggests to me that this remains an unresolved issue that requires a larger and/or longer study even with MRI-based measurement approaches.”

Glucosamine is an amino sugar and a prominent precursor in the biochemical synthesis of glycosylated proteins and lipids. It is part of the structure of the polysaccharides chitosan and chitin, which compose the exoskeletons of crustaceans and other arthropods, as well as the cell walls of fungi and many higher organisms. Since glucosamine is a precursor for glycosaminoglycans, and glycosaminoglycans are a major component of joint cartilage, some had hoped that supplemental glucosamine could beneficially influence cartilage structure, and alleviate OA.

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