What are glucosamine’s main benefits?

Glucosamine is a popular supplement for osteoarthritis, a disease characterized by excessive collagen degradation. However, the evidence supporting its effectiveness is not robust, and study results vary. One trial, known as the Glucosamine Unum In Die Efficacy (GUIDE) trial, which compared supplementation with a glucosamine sulfate-sodium chloride complex to placebo and to acetaminophen (the reference drug for osteoarthritis), found that the glucosamine preparation outperformed both placebo and acetaminophen at reducing knee arthritis severity scores. Although it was well designed, this trial has been criticized as it was sponsored by the same company that manufactured the glucosamine salt used, who not only provided funding but also carried out the statistical analysis.^[1] In contrast, a larger trial of interventions for knee osteoarthritis found that glucosamine alone had no significant effect on pain scores or on the OMERACT-OARSI response, which is a way to categorize how a people with osteoarthritis respond to treatment in clinical trials that was measured as a secondary outcome. However, an exploratory subgroup analysis noted a significant OMERACT-OARSI response to glucosamine treatment in individuals with moderate to severe pain, but not in people with mild pain; since this analysis was exploratory, this finding would need to be confirmed by futher research.^[2] Finally, one meta-analysis of interventions for hip and knee arthritis found that glucosamine may improve stiffness but does not significantly affect pain or physical function, whether used alone or in combination with chondroitin (another supplement often used for osteoarthritis and joint health).^[3] It’s also important to note that studies suggesting a positive impact of glucosamine on osteoarthritis indicate that it might slow down the disease progression rather than reverse it.

Research on soccer players and bicycle racers has found that in these athletic participants, glucosamine supplementation, particularly at a dose of 3 grams, was able to reduce levels of a biomarker associated with collagen breakdown, CPX-II. While collagen synthesis was not affected, these results suggest that glucosamine may help prevent collagen degradation.^[4][5] Another study involving participants with knee osteoarthritis who underwent a 12-week strength training program compared glucosamine (1500 mg) to a non-steroidal anti-inflammatory drug (NSAID) (1200 mg of ibuprofen) and found that glucosamine reduced exercise-related pain but did not impact muscle growth or power.^[6]

There are also potential uses for glucosamine sulfate in temporomandibular joint disorder (TMD). Glucosamine appears to reduce pain associated with TMD and increase mouth opening, but only when taken for over 3 months. However, as with osteoarthritis, there isn’t enough scientific evidence to support the use of glucosamine sulfate for symptomatic relief of TMD or as a modifier of the disease’s progression.^[7]