How Glucosamine Works
Glucosamine is found in high concentrations in the joints. It has been theorized that glucosamine stimulates the formation of cartilage that is essential for joint repair. In animal models, oral glucosamine sulfate has a beneficial effect on inflammation, mechanical arthritis, and immunological-reactive arthritis, though much less so than indomethacin and other such drugs.
Glucosamine is sometimes used in combination with chondroitin sulfate as a treatment for arthritis. Chondroitin sulfate is also found in cartilage and it reportedly maintains the viscosity in joints, stimulates cartilage repair mechanisms, and inhibits enzymes that break down cartilage.
Dietary Supplement
Glucosamine is sold in the United States as a dietary supplement. The Dietary Supplement Health and Education Act passed by Congress in 1994 allows the marketing of a product claimed to affect the structure or function of the body as a “dietary supplement” without the approval of any government agency.
The labeling must include a disclaimer that the product has not been evaluated by the FDA and the product is not intended to diagnose, treat, or prevent any disease.
Clinical Studies
In the 1990s, a series of short-term controlled studies suggested that glucosamine may be effective in relieving pain in people with osteoarthritis and for increasing their range of motion. Subsequent research has not been so convincing.
One of the largest glucosamine studies, called the Glucosamine/Chondroitin Arthritis Intervention Trial (GAIT), examined the effectiveness of glucosamine and chondroitin in 662 people with knee osteoarthritis. After two years, the investigators concluded that neither showed any benefit in relieving knee pain.
Even so, some researchers still contend that glucosamine not only helps ease arthritis pain but also prevents cartilage loss.
A 2015 study published in Arthritis Care & Research suggested that cartilage loss was reduced in adults with knee osteoarthritis who had taken glucosamine and chondroitin for up to six years. The benefits appeared to increase the longer the supplements are taken.
Meanwhile, a 2018 study in the British Journal of Sports Medicine suggested that glucosamine and chondroitin did provide some short-term relief, although physical function did not greatly improve.
In the long term, only chondroitin demonstrated a small but clinically significant improvement of joint function. The researchers could recommend neither glucosamine nor chondroitin to people with arthritis.
A Word From Verywell
The consensus is that glucosamine and chondroitin supplements might lessen pain in some people with osteoarthritis. However, the findings to date are contradictory, and it is difficult to suggest they are anywhere near the “cure” some hoped they would be.
They appear to be safe, but doctors are warning patients that the quality and effectiveness of glucosamine and chondroitin varies because of the non-regulation. If you want to try them, buy high-quality products from a reputable source.
