If you are one of the 242 million people who suffers from osteoarthritis, you likely know about glucosamine. Commonly paired with chondroitin, many praise its ability to ease hip and knee pain while some experts disagree on its efficacy. Environmental Nutrition examines the data on this popular dietary supplement.
Glucosamine, along with chondroitin, is a naturally occurring structural component of cartilage. Cartilage is the main type of connective tissue in the body, including joints. Glucosamine is thought to protect cells that help maintain cartilage structure. Individuals who experience painful inflammation and deterioration of cartilage with osteoarthritis or other joint disorders are interested in glucosamine supplementation in hopes of stimulating cartilage production and reducing pain. Glucosamine is available in tablets, capsules, or powders most commonly in the form of glucosamine sulfate or glucosamine hydrochloride. Glucosamine supplements can be synthetic or derived from shells of shellfish.
The most comprehensive long-term study examining the efficacy and safety for the treatment of osteoarthritis knee pain is the Glucosamine/Chondroitin Arthritis Intervention Trial (GAIT). The GAIT study evaluated glucosamine and chondroitin sulfate individually and in combination compared to a drug (celecoxib) and a placebo in nearly 1,600 people. Glucosamine and chondroitin sulfate alone or in combination didn’t result in significant pain relief in general but was effective in a subgroup of individuals with moderate-to-severe knee pain.
A follow-up study reported that the supplements improved pain and function but not significantly more than placebo or celecoxib. Another similar study called the MOVES trial observed that the combination of glucosamine hydrochloride and chondroitin sulfate was as effective at relieving knee pain and swelling as celecoxib. Mixed results between trials may be due to the variety of supplement types and doses examined.
Safety and side effects
Oral glucosamine is considered safe in appropriate amounts (~1,500-2,000 milligrams/day) and is generally well-tolerated when taken with food. Side effects are usually mild and include nausea, heartburn, constipation, diarrhea, or headache. Individuals with shellfish allergies should use caution. Some evidence suggests that glucosamine may cause insulin resistance and increase serum glucose.
Taking glucosamine alone or with chondroitin may increase the effects of blood thinners (warfarin) and increase risk of bleeding. Glucosamine sulfate in combination with acetaminophen may reduce the effectiveness. Before starting any new supplement, check with your doctor to make sure it’s appropriate for you.