Since glucosamine is a precursor for glycosaminoglycans, and glycosaminoglycans are a major component of cartilage, research has focused on the potential for supplemental glucosamine to beneficially influence cartilage structure and alleviate arthritis.
Two studies measured the concentrations of glucosamine in the synovial fluid and plasma after oral administration of glucosamine sulfate to both healthy volunteers and people with osteoarthritis [REF].