Glucosamine supplements were no better than placebo at improving cartilage damage in patients with knee osteoarthritis in a randomized trial that was described by study investigators as the first "to evaluate the benefit of glucosamine on joint health using two different MRI parameters to measure outcomes."
Dr. C. Kent Kwoh of the University of Pittsburgh and the University of Arizona, Tucson, and his associates randomly assigned 201 patients to receive 6 months of either 1,500 mg daily oral glucosamine hydrochloride in the form of a diet lemonade drink (98 patients) or a matching placebo (103 patients). The study participants, aged 35-65 years, all had mild to moderate chronic, frequent knee pain typical of osteoarthritis (OA).
The primary outcome was the inhibition of worsening cartilage damage in both knees, as assessed using detailed MRI examination of 14 articular subregions in each joint. Cartilage status declined in both groups to the same degree, and there was no evidence that glucosamine lessened the deterioration of knee cartilage. There was worsening in at least one knee subregion in 7.7% of glucosamine-treated knees and 10.7% of placebo-treated knees, and in at least two subregions in 5.1% of those treated with glucosamine and 4.4% of those treated with placebo.
Subchondral bone marrow lesions ("bone bruises"), another feature of cartilage damage, also showed either worsening or no change in both study groups. In fact, "changes in bone marrow lesions suggested that there was less worsening and more improvement in the control group as compared to the glucosamine group," the investigators wrote.
In addition to these assessments of structural changes, the investigators also examined a molecular biomarker of cartilage tissue degradation: the urinary level of C-terminal cross-linking telopeptide of type II collagen, which correlates with radiographic progression of OA. Again, there were no differences between the two study groups after 6 months of treatment. Similarly, the study participants indicated in subjective measures of knee pain and function that glucosamine yielded no benefits (Arthritis Rheumatol. 2014 March 11 [doi:10.1002/art.38314]).
The evidence concerning glucosamine’s effectiveness in improving joint health is "very conflicting," with independent studies showing no benefit while industry-sponsored studies show the opposite. Nevertheless, glucosamine is the second most commonly used nutraceutical in the United States, and a 2007 study showed that more than 10% of American adults take it. "Global sales of glucosamine supplements increased over 60% between 2003 ($1.3 billion) and 2010 (over $2.1 billion)," Dr. Kwoh and his associates wrote.
This study was funded by the Coca-Cola Beverage Institute for Health & Wellness and the National Institute of Arthritis and Musculoskeletal and Skin Diseases. No other financial conflicts of interest were reported.